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Solar Glint and Glare Study

Wentlooge

March, 2020

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Solar Glint and Glare Study Wentlooge 2

ADMINISTRATION PAGE

Job reference: 9185D

Date: 7th November, 2019

Author: Andrea Mariano

Telephone:

Email:

Reviewer: Kai Frolic

Date: 7th November, 2019

Telephone:

Email:

Issue Date Detail of Changes

1 7th November, 2019 Initial issue

2 12th March, 2020 Minor amendments – note on updated layout

Confidential: The contents of this document may not be disclosed to others without permission.

Copyright ©2020 Pager Power Limited

Stour Valley Business Centre, Unit 2, Brundon Lane, Sudbury, CO10 7GB

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EXECUTIVE SUMMARY

Report Purpose

Pager Power has been retained to assess the possible effects of the proposed Wentlooge solar

development1, located near Blacktown, Marshfield, Cardiff, UK. The assessment is specifically

regarding the proposed development with respect to glint and glare effects upon adjacent

dwellings, roads and railway operations on the nearby section of railway.

Pager Power

Pager Power has undertaken over 400 glint and glare assessments in Europe, India and

Australasia. The company’s own glint and glare guidance is based on industry experience and

extensive consultation with industry stakeholders including airports and aviation regulators.

Guidance

Guidelines exist in the UK, which have been produced by the Civil Aviation Authority (CAA) with

respect to glint, glare and aviation activity for solar photovoltaic panels. There is railway guidance

with respect to signal siting however no guidance with respect to glint and glare from solar panels

developments and railway infrastructure has been specifically produced. Similarly, there is no

existing guidance for the assessment of solar reflections from solar panels towards roads and

nearby dwellings. Pager Power has however produced guidance for glint and glare and solar

photovoltaic developments which was published in early 2017, with the second edition

published in 2018. The guidance document sets out the methodology for assessing roads,

dwellings and railway operations with respect to solar reflections from solar panels.

The Pager Power approach is to identify receptors, undertake geometric reflection calculations

whilst comparing the results against available solar reflection studies. Previous consultation with

Network Rail and completing glint and glare assessment for railway infrastructure has been used

to produce an overall methodology for railway operation.

Studies have measured the intensity of solar reflections from various naturally occurring and

manmade surfaces. The results show that the intensity of solar reflections from glass are slightly

higher than those from still water but significantly less than those from steel2.

Glint and Glare

The definition of glint and glare used by Pager Power is as follows:

• Glint – a momentary flash of bright light;

• Glare – a continuous source of bright light.

1 Updated layout.

2 SunPower, 2009, SunPower Solar Module Glare and Reflectance (appendix to Solargen Energy,2010).

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Overview

Pager Power has been retained to assess the possible Glint and Glare effects of the proposed

Wentlooge solar development, located near Blacktown, Marshfield, Cardiff, UK. The assessment

is specifically regarding the potential impact upon adjacent dwellings, roads and railway

operations on a nearby section of railway.

Railway Signal

Four railway signals have been assessed. Based on the results of the analysis, a solar reflection

is deemed possible. However, the impact will be mitigated by the expected presence of a signal

hood. Pager Power suggests carrying out an on-site assessment to establish if the signals have

hoods since it was not possible to establish it from available imagery.

If the on-site assessment establishes that the signals do not have a hood provision of further

screening should be considered. The identified issues are likely to be resolvable and are not

predicted to result in planning refusal – see Section 8.2 on page 79.

Train Driver

The analysis undertaken considered 30 train driver observer points which cover a total of 3km

of railway. Results and available imagery show that an unscreened geometric reflection is

possible and unscreened for 5 points, but it will only affect trains travelling in south-west/north-

east direction. For these points, a moderate impact is expected – see Section 8.3 on page 79.

Roads

The analysis carried out considered 64 road driver observer points which cover a total of 6.1km

of road. The results for each road are presented below:

• Ty Mawr Lane: all receptors showed either no reflection possible or sufficient existing

screening is present – see Section 8.4.1 on page 82.

• Hawrse Lane: for receptors where reflection is concurrently possible and unscreened

the impact is categorised as low. Therefore, no mitigation is suggested – see Section

8.4.2 on page 82.

• Broadway: for receptors where reflection is concurrently possible and unscreened the

impact is categorised as low. Therefore, no mitigation is suggested – see Section 8.4.3

on page 82.

• B4239: for receptors where reflection is concurrently possible and unscreened the

impact is categorised as low – see Section 8.4.4 on page 82.

Therefore, no mitigation is suggested for any of the roads assessed.

Dwellings

The available imagery showed 20 dwellings requiring assessment, of which moderate effects

were predicted at five. It is estimated that effects could last for 30 minutes per day. These

dwellings are within 200m of the proposed development. These conclusions are based on a

conservative assessment of visibility – see Section 8.5 at page 82.

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Provision of further screening should be considered.

Overall Conclusions and Recommendations

The assessment of the proposed development showed that for some of the railway’s observers

the impact is deemed as moderate. The location of the proposed development relative to the

railway line is comparable with similar consented schemes such as those at Westbury and

Stretham (see Section 8.3). These have been in operation for a number of years, demonstrating

the compatibility of solar developments alongside railway lines. Engagement with Network Rail

is recommended to share the results of this assessment and ensure that plans for the

development are communicated in a clear and inclusive fashion.

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LIST OF CONTENTS

Administration Page ...................................................................................................................... 2

Executive Summary ....................................................................................................................... 3

Report Purpose ............................................................................................................................... 3

Pager Power .................................................................................................................................... 3

Guidance .......................................................................................................................................... 3

Glint and Glare ................................................................................................................................ 3

Overview .......................................................................................................................................... 4

Railway Signal ................................................................................................................................. 4

Train Driver ..................................................................................................................................... 4

Roads 4

Dwellings .......................................................................................................................................... 4

Overall Conclusions and Recommendations ............................................................................ 5

List of Contents .............................................................................................................................. 6

List of Figures ................................................................................................................................. 9

List of Tables ................................................................................................................................ 10

About Pager Power .................................................................................................................... 11

1 Introduction .................................................................................................................... 12

1.1 Overview ............................................................................................................................ 12

1.2 Pager Power’s Experience .............................................................................................. 12

1.3 Glint and Glare Definition ............................................................................................... 13

2 Proposed Development Location and Details ......................................................... 14

2.1 Proposed Development Location and Boundary ....................................................... 14

2.2 Proposed Development Site Plan ................................................................................. 15

2.3 Proposed Development Location and Details ............................................................ 16

3 Network Rail ................................................................................................................... 18

3.1 Overview ............................................................................................................................ 18

3.2 Modelling Approach ......................................................................................................... 18

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4 Glint and Glare Assessment Methodology ............................................................... 19

4.1 Overview ............................................................................................................................ 19

4.2 Methodology and Consultation ..................................................................................... 19

5 Identification of Receptors .......................................................................................... 20

5.1 Overview ............................................................................................................................ 20

5.2 Railway Signal Locations ................................................................................................. 20

5.3 Train Driver Locations ..................................................................................................... 22

5.4 Roads .................................................................................................................................. 24

5.5 Dwellings ............................................................................................................................ 27

6 Modelling the Solar Development ............................................................................. 29

6.1 Overview ............................................................................................................................ 29

6.2 Reflector Areas ................................................................................................................. 29

7 Glint and Glare Assessment Results .......................................................................... 30

7.1 Overview ............................................................................................................................ 30

7.2 Geometric Calculation Results Overview – Railway Signals ................................... 31

7.3 Geometric Calculation Results Overview – Train Driver Location ........................ 32

7.4 Geometric Calculation Results Overview – Ty Mawr Lane ..................................... 45

7.5 Geometric Calculation Results Overview – Hawrse Lane ....................................... 49

7.6 Geometric Calculation Results Overview – Broadway ............................................. 55

7.7 Geometric Calculation Results Overview – B4239 ................................................... 62

7.8 Geometric Calculation Results Overview – Dwellings ............................................. 74

8 Geometric Assessment Results and Discussion ...................................................... 79

8.1 Overview ............................................................................................................................ 79

8.2 Railway Signal Results ..................................................................................................... 79

8.3 Train Driver Results ......................................................................................................... 79

8.4 Roads .................................................................................................................................. 82

8.5 Dwellings Results ............................................................................................................. 82

9 Overall Conclusions ...................................................................................................... 86

9.1 Overview ............................................................................................................................ 86

9.1 Railway Signal conclusions ............................................................................................. 86

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9.2 Train Driver conclusions ................................................................................................. 86

9.3 Road conclusions .............................................................................................................. 86

9.4 Dwellings conclusions ..................................................................................................... 86

9.5 Overall Conclusions and Recommendations .............................................................. 87

Appendix A – Overview of Glint and Glare Guidance ......................................................... 88

Overview ........................................................................................................................................ 88

UK Planning Policy ....................................................................................................................... 88

Assessment Process..................................................................................................................... 89

Railway Assessment Guidelines ................................................................................................ 89

Appendix B – Overview of Glint and Glare Studies ............................................................. 93

Overview ........................................................................................................................................ 93

Reflection Type from Solar Panels ............................................................................................ 93

Solar Reflection Studies .............................................................................................................. 94

Appendix C – Overview of Sun Movements and Relative Reflections ............................ 97

Terrain Sun Curve - From lon: -3.042406 lat: 51.53006 ..................................................... 98

Appendix D – Pager Power’s Reflection Calculations Methodology ............................... 99

Appendix e – Glint and Glare Impact Significance ............................................................. 101

Overview ...................................................................................................................................... 101

Impact Significance Definition ................................................................................................. 101

Appendix F – Assessment Limitations and Assumptions .................................................. 102

Assessment process for Train Driver Receptors .................................................................. 103

Assessment Process for Road Receptors .............................................................................. 104

Assessment Process for Dwelling Receptors ....................................................................... 105

Appendix G – Assessment Limitations and Assumptions ................................................. 106

Pager Power’s Model ................................................................................................................. 106

Appendix H – Receptor and Reflector Area Details .......................................................... 107

Roads receptors .......................................................................................................................... 107

Dwellings Locations ................................................................................................................... 110

Signal Locations .......................................................................................................................... 110

Train Driver Receptor Locations ............................................................................................. 112

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Reflector Details ......................................................................................................................... 114

Appendix I – Geometric Calculation Results – Pager Power Results ............................. 115

Train Signals Receptors Results ............................................................................................... 115

Train Driver Receptors Results ................................................................................................ 117

Roads Receptors Results .......................................................................................................... 131

Dwellings Receptors Results .................................................................................................... 160

LIST OF FIGURES

Figure 1 – Proposed development location .......................................................................... 14

Figure 2 – Proposed development site plan .......................................................................... 15

Figure 3 – Layout of proposed development (heights and inclination) ........................... 16

Figure 4 – Layout of proposed development (panels orientation) .................................... 17

Figure 5 – Signal visible from Broadway (travelling towards Cardiff) .............................. 21

Figure 6 – Signal visible from Hawrse Lane (travelling towards Cardiff) ......................... 21

Figure 7 – Location of the signal relative to the development .......................................... 22

Figure 8 – Train driver receptor locations ............................................................................. 23

Figure 9 – Ty Mawr Lane receptor location .......................................................................... 24

Figure 10 – Hawrse Lane receptor location .......................................................................... 25

Figure 11 – Broadway receptor location ............................................................................... 26

Figure 12 – B4239 receptor location...................................................................................... 27

Figure 13 – Dwellings location ................................................................................................. 28

Figure 14 – Assessed reflectors area ...................................................................................... 29

Figure 15 – Train driver: observation points which can possibly experience solar

reflection ....................................................................................................................................... 80

Figure 16 – Solar development near Westbury .................................................................... 81

Figure 17 – Solar development near Stretham ..................................................................... 81

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Figure 18 – Dwellings: observation points which can possibly experience solar reflection

........................................................................................................................................................ 83

LIST OF TABLES

Table 1 – Geometric glint and glare calculation results: Railway signals ......................... 31

Table 2 – Geometric glint and glare calculation results – Train driver locations ........... 44

Table 3 – Geometric glint and glare calculation results – Ty Mawr Lane ....................... 48

Table 4 – Geometric glint and glare calculation results – Hawrse Lane .......................... 54

Table 5 – Geometric glint and glare calculation results – Broadway ............................... 61

Table 6 – Geometric glint and glare calculation results – B4239 ..................................... 73

Table 7 – Geometric glint and glare calculation results – Dwellings ................................ 78

Table 8 – Affected dwellings comments ................................................................................ 85

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ABOUT PAGER POWER

Pager Power is a dedicated consultancy company based in Suffolk, UK. The company has

undertaken projects in 48 countries within Europe, Africa, America, Asia and Australasia.

The company comprises a team of experts to provide technical expertise and guidance on a range

of planning issues for large and small developments.

Pager Power was established in 1997. Initially the company focus was on modelling the impact

of wind turbines on radar systems. Over the years, the company has expanded into numerous

fields including:

• Renewable energy projects;

• Building developments;

• Aviation and telecommunication systems.

Pager Power prides itself on providing comprehensive, understandable and accurate

assessments of complex issues in line with national and international standards. This is

underpinned by its custom software, longstanding relationships with stakeholders and active role

in conferences and research efforts around the world.

Pager Power’s assessments withstand legal scrutiny and the company can provide support for a

project at any stage.

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1 INTRODUCTION

1.1 Overview

Pager Power has been retained to assess the possible Glint and Glare effects of the proposed

Wentlooge solar development, located near Blacktown, Marshfield, Cardiff, UK. The assessment

is specifically regarding the potential impact upon adjacent dwellings, roads and railway

operations on a nearby section of railway.

Savills has requested an assessment to determine whether the solar reflections would create a

significant impact. This assessment therefore contains the following:

• Explanation of glint and glare;

• Development details;

• Overview of relevant guidance;

• Overview of relevant studies;

• Overview of Sun movement;

• Assessment methodology;

• Identification of receptors including;

o Train driver locations;

o Railway signals;

o Road user location;

o Dwellings;

• Glint and glare assessment for identified receptors;

• Results discussion.

1.2 Pager Power’s Experience

Pager Power has undertaken over 400 Glint and Glare assessments in the UK and internationally.

The studies have included assessment of civil and military aerodromes, railway infrastructure and

other ground-based receptors including roads and dwellings.

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1.3 Glint and Glare Definition

The definition of glint and glare can vary, however, the definition used by Pager Power is as

follows:

• Glint – a momentary flash of bright light typically received by moving receptors or from

moving reflectors;

• Glare – a continuous source of bright light typically received by static receptors or from

large reflective surfaces.

These definitions are aligned with those of the Federal Aviation Administration (FAA) in the

United States of America. The term ‘solar reflection’ is used in this report to refer to both

reflection types i.e. glint and glare.

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2 PROPOSED DEVELOPMENT LOCATION AND DETAILS

2.1 Proposed Development Location and Boundary

The location (red line) of the proposed development3 is shown in Figure 14 below. The blue lines

indicate the ecology area.

Figure 1 – Proposed development location

3 The image shows the updated layout of the proposed solar development. For the glint and glare technical modelling an

older and different version was considered. The newer version has a marginally smaller reflective area. However, the

results of the previous modelling remain valid because the changes are predicted to be minimal, and the potential effects

for a smaller area can only be 1) unchanged, or 2) reduced. 4 Source: SITE LAYOUT PLAN, Savills, date: 20/02/2020, cropped.

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2.2 Proposed Development Site Plan

The location and layout of the proposed development (yellow line) is shown in Figure 25 below.

Figure 2 – Proposed development site plan

5 Source: Aerial image copyright © 2019 Google.

Blacktown

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2.3 Proposed Development Location and Details

The arrangement of the solar panels is shown in Figure 3 and Figure 46 below and on the next

page. Their details are as follows:

• Panel centre height of 1.86 metres above ground level (Figure 3);

• Vertical tilt angle of 15 degrees from the horizontal (Figure 3);

• The panel azimuth angle is 180 degrees (south-facing) (Figure 4).

Figure 3 – Layout of proposed development (heights and inclination)

6 Source: Savills

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Figure 4 – Layout of proposed development (panels orientation)


3 NETWORK RAIL

3.1 Overview

Network Rail often requests further information regarding the potential effects of glint and glare

from reflective surfaces when a proposed development is located adjacent to a railway line. The

following section presents the steps taken to understand the technical effects.

3.2 Modelling Approach

The key receptors identified and modelled within this report are:

• Train driver locations.

• Railway signal locations.

Modelling has been undertaken to quantify the extent of potential reflections towards these

receptors and assess the impact accordingly. Section 4 and the report appendices set out the

methodology in more technical detail.

Many railway signals are now LED. The benefits of an LED signal over a filament bulb signal with

respect to possible phantom aspect illuminations are as follows:

• An LED railway signal produces a more intense light making them more visible to

approaching trains when compared to the traditional filament bulb technology7;

• LED signals can operate without a reflective mirror present unlike a filament bulb8. The

presence of the reflective surfaces greatly increases the likelihood of incoming light

being reflecting out making the signal appear illuminated;

• LED signal manufacturers9,10,11 claim that LED signal lights significantly reduce or

completely remove the likelihood of a phantom aspect illumination occurring.

Details regarding the identified railway signals are presented in Section 5 of this report.

7 Source: Wayside LED Signals – Why it’s Harder than it Looks, Bill Petit. 8 This can vary from one manufacturer to another. 9 Source: http://www.unipartdorman.co.uk/assets/unipart_dorman_rail_brochure.pdf. (Last accessed 21.02.18). 10 Source: http://www.vmstech.co.uk/downloads/Rail.pdf. (Last accessed 21.02.18). 11 Source: Siemens, Sigmaguard LED Tri-Colour L Signal – LED Signal Technology at Incandescent Prices. Datasheet 1A-

23. (Last accessed 22.02.18).


4 GLINT AND GLARE ASSESSMENT METHODOLOGY

4.1 Overview

Appendix A presents a review of planning and rail guidance and Appendix B presents

independent studies with regard to glint and glare issues. Key points from the literature are:

• Specular reflections of the Sun from solar panels are possible.

• The measured intensity of a reflection from solar panels can vary from 2% to 30%

depending on the angle of incidence.

• The intensity of reflections from solar panels are equal to or less than those from water.

Reflections from solar panels are significantly less intense than many other reflective

surfaces which are common in an outdoor environment.

4.2 Methodology and Consultation

The glint and glare assessment methodology has been derived from the information provided to

Pager Power through consultation with stakeholders and by reviewing the available guidance.

The methodology for the glint and glare assessment is shown below.

• Identify receptors in the area surrounding the proposed solar development.

• Consider direct solar reflections from the proposed solar development towards the

identified receptors by undertaking geometric calculations.

• Consider the visibility of the panels from the receptor’s location. If the panels are not

visible from the receptor then no reflection can occur.

• Based on the results of the geometric calculations, determine whether a reflection can

occur, and if so, at what time it will occur.

• Consider both the solar reflection from the proposed solar development and the location

of the direct sunlight with respect to the receptor’s position.

• Consider the solar reflection with respect to the published studies and guidance.

• Determine whether a significant detrimental impact is expected in accordance with the

methodology presented in Appendix D.

• Consider mitigation.


5 IDENTIFICATION OF RECEPTORS

5.1 Overview

This assessment has been carried out with specific reference to potential impacts upon adjacent

dwellings, roads and railway operations on the nearby section of railway, in accordance with

Pager Power’s guidance.

There is no formal guidance with regard to the maximum distance at which glint and glare should

be assessed. From a technical perspective, there is no maximum distance for potential

reflections.

However, the significance of a solar reflection decreases with distance. This is because the

proportion of an observer’s field of vision that is taken up by the reflecting area diminishes as

the separation distance increases.

Terrain and shielding by vegetation are also more likely to obstruct an observer’s view at longer

distances for ground-based receptors.

5.2 Railway Signal Locations

The impact of solar reflections upon railway signals has been assessed by considering the height

and location of any identified signals. Information about the signals location were extrapolated

from available imagery1213 (Figure 5 below and Figure 6 on the next page) showing that the

railway’s section has four signals (red circles). The location of the signals relative to the proposed

development is shown in Figure 714 on page 22.

12 consultation with Network Rail has been undertaken to confirm these details and that at the time of writing these have

not been received. 13 Source: Copyright © 2019 Google.


Figure 5 – Signal visible from Broadway (travelling towards Cardiff)

Figure 6 – Signal visible from Hawrse Lane (travelling towards Cardiff)


Figure 7 – Location of the signal relative to the development

The railway signals details are presented in Appendix H.

5.3 Train Driver Locations

The impact of a solar reflection is determined by identifying locations along sections of railway

lines north of the proposed development that could potentially receive a solar reflection from

the reflective surfaces on the proposed development.

There are four railway lines running adjacent to the proposed development. The lines have been

assessed as one, since the distance between the lines is in average approximately 2m. Visibility

and direction of travel is considered in the assessment. The total length of each assessed railway

line is 3km. In total 30 receptor locations have been assessed, one every 100m. Locations 1a and

1b are the additional locations included in the assessment due to the extension of the solar

development. The location of the assessed train driver receptors (yellow circles) on the assessed

length of railway line (blue line) is shown in Error! Reference source not found.14 on the following p

age.

The train driver receptor details are presented in Appendix H.

14 Copyright © 2019 Google.


Figure 8 – Train driver receptor locations


5.4 Roads

The analysis has considered through-roads that:

• Are within, or close to one kilometre of the proposed development; and

• Have a potential view of the panels.

The assessed road receptor points are shown as blue icons and green lines in Figure 9, Figure 10,

Figure 11 and Figure 1215 below and in the following pages. Ty Mawr Lane is located 350 meters

(at its closest point) north-west of the solar development (points 29 – 38), Hawrse Lane is located

50 meters (at its closest point) north-east of the solar development (points 39 – 53), Broadway

is located 75 meters (at its closest point) south-west of the solar development (points 54 – 67)

and the B4239 is located 10 meters (at its closest point) south of the solar development (points

68 – 92). A height above ground level of 1.5 metres has been taken as typical eye level for a road

user for all roads. The co-ordinates of the receptor points are presented in Appendix H.

Figure 9 – Ty Mawr Lane receptor location

15 Source: Copyright © 2019 Google.


Figure 10 – Hawrse Lane receptor location


Figure 11 – Broadway receptor location


Figure 12 – B4239 receptor location

5.5 Dwellings

The analysis has considered dwellings that:

• Are within, or close to one kilometre of the proposed development; and

• Have a potential view of the panels.

The assessed dwellings are shown in Figure 1316 on the following page. Some dwellings are

located close to the site boundary (93 to 101), others are located further away but within 1km

range of the proposed solar development. A height above ground level of 1.8 metres has been

taken as the typical eye level for an observer on the ground floor of each dwelling. The

co-ordinates of the receptor points are presented in Appendix H.

16 Source: Copyright © 2019 Google.


Figure 13 – Dwellings location


6 MODELLING THE SOLAR DEVELOPMENT

6.1 Overview

The following section presents the modelled reflectors: solar panels.

6.2 Reflector Areas

A number of representative panel locations are selected within the proposed solar development

site boundary. The number of locations is determined by the size of the proposed solar

development and the assessment resolution. The bounding co-ordinates for the proposed solar

development have been extrapolated from the available site maps. The assessment is considered

conservative and robust. All ground heights have been taken from Pager Power’s database.

Boundary coordinate data is shown in Appendix G.

A resolution of 30m has been chosen for this assessment. This means that a geometric

calculation is undertaken for each identified receptor every 30m from within the defined solar

development area. This resolution is sufficiently high to maximise the accuracy of the results –

increasing the resolution further would not significantly change the modelling output. If a

reflection is experienced from an assessed panel location, then it is likely that a reflection will be

viewable from similarly located panels within the development.

Figure 14 – Assessed reflectors area


7 GLINT AND GLARE ASSESSMENT RESULTS

7.1 Overview

The following section presents an overview of the glare for the identified receptors. Appendix I

presents the results charts of the Pager Power modelling.


7.2 Geometric Calculation Results Overview – Railway Signals

The results of the geometric calculations for the railway signals are presented in Table 1 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward the Railway Signals (GMT)

am pm

Light signal

1 – 2

Between 05:32 and 06:19 from mid-

March to late September. None.

Geometric reflection is possible. During the

morning, the solar reflection and direct sunlight will

originate from the same location. However, no

screening has been identified.

Moderate impact expected.



Light signal

3 – 4


March to mid-May. At circa 05:34 during

the end of May. At circa 05:42 during

mid-July. Between 05:49 and 06:06 from

the end of July to late September.

None. Geometric reflection is possible. During the

morning, the solar reflection and direct sunlight will

originate from the same location. However,

screening has been identified.

Moderate impact expected. Between 05:37 and 06:18 from late

March to early June. Between 05:39 and

06:04 from early July to late September.

None.

Table 1 – Geometric glint and glare calculation results: Railway signals


7.3 Geometric Calculation Results Overview – Train Driver Location

The results of the geometric calculations for the train driver locations are presented in Table 2 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward the Railway Driver Locations (GMT)

am pm

1b None. None. None.

1a None. None. None.

1 None. None. None.

2 At circa 06:17 during late March. At

circa 06:00 during mid-September. None.

Pager Power model predicts solar reflection at this

location. The reflection will be generated from the

northern portion of the proposed development.

However, the reflective surface area is extremely

small.

Low impact expected.


Receptor

Pager Power Results


am pm

3

Between 06:17 and 06:18 during

late March. Between 06:00 and

06:02 during early April. At circa

05:45 during the end of April. At

circa 05:53 during mid-August.

Between 05:59 and 06:00 during the

beginning of September. At circa

06:03 during late September.

None.





small.


4

Between 05:42 and 06:19 from late

March to early May. Between 05:35

and 05:37 during late May. At circa

05:35 during early June. At circa

05:41 during early July. Between

05:45 and 05:46 during late July.

Between 05:51 and 06:00 from early

August to early September. Between

06:03 and 06:04 during late

September.

None.





small.



Receptor

Pager Power Results


am pm

5


March to late May. Between 05:34

and 05:35 during late June. Between

05:44 and 06:07 from mid-July to

late September.

None.





small.


6 Between 05:33 and 06:21 from mid-




northern portion of the proposed development. No

existing screening identified. Existing screening

identified, but possibly insufficient to screen the

reflection.



Receptor

Pager Power Results


am pm








reflection.









reflection.



Receptor

Pager Power Results


am pm


March to the end of September. None.






reflection.









reflection.



Receptor

Pager Power Results


am pm







small.






northern-central portion of the proposed

development. Screening in form of vegetation has

been identified.



Receptor

Pager Power Results


am pm







been identified.








been identified.



Receptor

Pager Power Results


am pm

15 Between 05:32 and 06:17 from late






been identified.








been identified.



Receptor

Pager Power Results


am pm







been identified.






central portion of the proposed development.

Screening in form of vegetation has been identified.







Screening in form of vegetation has been identified.



Receptor

Pager Power Results


am pm





central portion of the proposed development. The

reflection will not generate in front of the train

driver.








driver.








driver.Low impact expected.


Receptor

Pager Power Results


am pm






reflection will generate outside the driver’s field of

vision.








driver.



Receptor

Pager Power Results


am pm







driver.








driver.



Receptor

Pager Power Results


am pm





central-southern portion of the proposed

development. The reflection will not generate in

front of the train driver.






central-southern portion of the proposed

development. The reflection will not generate in

front of the train driver.


Table 2 – Geometric glint and glare calculation results – Train driver locations


7.4 Geometric Calculation Results Overview – Ty Mawr Lane

The results of the geometric calculations for drivers travelling on Ty Mawr Lane are presented in Table 3 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward Ty Mawr Lane (GMT)

am pm






Reflection will not generate in front of the driver.

Also, existing screening in form of vegetation has

been identified.

No impact is predicted in practice.

30


March to the beginning of June.

Between 05:40 and 06:03 from early

July to late September.

None.






been identified.



Receptor

Pager Power Results


am pm

31


March to mid-May. Between 05:46

and 06:03 from late July to late

September.

None.






been identified.


32


March to early May. Between 05:50

and 06:03 from early August to late

September.

None.






been identified.



Receptor

Pager Power Results


am pm

33


March to the end of April. Between

05:53 and 06:03 from mid- August to

late September.

None.






been identified.


34


March to mid-April. Between 05:56

and 06:03 from late August to late

September.

None.






been identified.



Receptor

Pager Power Results


am pm

35


March to early April. Between 06:00

and 06:03 from early September to

late September.

None.






been identified.


36

Between 06:12 and 06:17 during late

March. Between 06:01 and 06:03

during mid-September.

None.






been identified.


37 None. None. None.


Table 3 – Geometric glint and glare calculation results – Ty Mawr Lane


7.5 Geometric Calculation Results Overview – Hawrse Lane

The results of the geometric calculations for drivers travelling on Hawrse Lane are presented in Table 4 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward Hawrse Lane (GMT)

am pm




42 None. At circa 18:30 during late April. At

circa 18:33 during mid-August.



northern portion of the proposed development and

the reflective surface area is extremely small.




Receptor

Pager Power Results


am pm

43 None.


March to mid-May. Between 18:52

and 18:57 during June. From 18:16

and 18:51 from late July to mid-

September.




Existing screening in form of vegetation has been

identified.


44 None.


March to early June. Between 18:06

and 18:55 from early July to late

September.






45 None. Between 18:11 and 18:55 from late

March mid-September.





Low impact predicted.


Receptor

Pager Power Results


am pm


March to mid-September.




Existing screening in form of vegetation and

buildings has been identified.


47 None. Between 18:06 and 18:55 from mid-

March to late September.





buildings has been identified. Also, reflection will not

generate in front of the driver.



Receptor

Pager Power Results


am pm







buildings has been identified. Also, reflection will not

generate in front of the driver.






northern and central portion of the proposed

development. Reflection will not generate in front of

the driver.



Receptor

Pager Power Results


am pm























Receptor

Pager Power Results


am pm








Table 4 – Geometric glint and glare calculation results – Hawrse Lane


7.6 Geometric Calculation Results Overview – Broadway

The results of the geometric calculations for drivers travelling on Broadway are presented in Table 5 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward Broadway (GMT)

am pm

54


March to the end of May. Between

05:41 and 06:02 from early July to late

September.

None.




development. Existing screening in form of

vegetation and buildings has been identified.











Receptor

Pager Power Results


am pm


















Receptor

Pager Power Results


am pm







identified.








identified.



Receptor

Pager Power Results


am pm







vegetation has been identified.






central and southern portion of the proposed


vegetation has been identified.



Receptor

Pager Power Results


am pm





southern portion of the proposed development.


identified.


63 Between 05:32 and 06:17 mid- March

to late September. None.





identified.



Receptor

Pager Power Results


am pm







the driver.








the driver.



Receptor

Pager Power Results


am pm

66 Between 05:32 and 06:08 from the

end of March to mid-September. None.





the driver.


67


March to early September. At circa

06:01 during mid-September.

None.





the driver.


Table 5 – Geometric glint and glare calculation results – Broadway


7.7 Geometric Calculation Results Overview – B4239

The results of the geometric calculations for drivers travelling on the B4239 are presented in Table 6 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward B4239 (GMT)

am pm







identified.








identified.



Receptor

Pager Power Results


am pm







identified.








identified.



Receptor

Pager Power Results


am pm







identified.








the driver.

Low impact is predicted.









Receptor

Pager Power Results


am pm






Existing screening in form of vegetation will mitigate

the issue.







Reflection will generate not generate in front of the

driver.



Receptor

Pager Power Results


am pm







driver.








buildings will mitigate the issue.



Receptor

Pager Power Results


am pm


March to mid- September.





driver.








driver.



Receptor

Pager Power Results


am pm

81 None. Between 18:23 and 18:55 from early

April to the beginning of September.





driver.


82

At circa 05:37 during mid- May.

Between 05:47 and 05:48 during the

beginning of August.

At circa 18:35 during the end of

April. At circa 18:42 during mid-

August.





small.



Receptor

Pager Power Results


am pm

83

Between 05:53 and 05:58 during mid-

April. Between 05:32 and 05:48 from

mid-May to the end of July. Between

05:56 and 05:57 during the end of

August.

None.





small.


84


April to early June. Between 05:37 and

05:56 from the beginning of July to

late August.

None.





identified.



Receptor

Pager Power Results


am pm

85

Between 05:32 and 05:45 from the

end of April to mid- June. Between

05:36 and 05:49 from the end of June

to the beginning of August. At circa

05:52 during mid- August

None.





identified.


86 Between 05:32 and 05:50 from early

May to early August. None.





identified.



Receptor

Pager Power Results


am pm


May to the beginning of August. None.








May to the end of July. None.








Receptor

Pager Power Results


am pm


May to late July. None.
















Receptor

Pager Power Results


am pm









92

Between 05:32 and 05:33 from the

end of May to early June. Between

05:33 and 05:42 from mid- June to

mid- July.

None.







Table 6 – Geometric glint and glare calculation results – B4239


7.8 Geometric Calculation Results Overview – Dwellings

The results of the geometric calculations for the nearby dwellings locations are presented in Table 3 below.

Receptor

Pager Power Results

Reflection Expected Possible reflection toward nearby dwellings (GMT)

am pm

92


March to late April. Between 05:54

and 06:03 from mid-August to late

September.

None.





identified.







development. No screening identified.



Receptor

Pager Power Results


am pm













central southern portion of the proposed








central portion of the proposed development. No

screening identified.



Receptor

Pager Power Results


am pm













identified.






southern portion of the proposed development. No




Receptor

Pager Power Results


am pm





southern portion of the proposed development. No




102 Between 05:32 and 05:42 from the

end of May to mid-July. None.








Receptor

Pager Power Results


am pm

103


May to the beginning of June.


June to late July.

None.







Table 7 – Geometric glint and glare calculation results – Dwellings


8 GEOMETRIC ASSESSMENT RESULTS AND DISCUSSION

8.1 Overview

The results of the railway, dwellings and roads glint and glare calculations are presented in the

following sub-sections. See the solar reflection charts in Appendix I for the individual solar

reflection charts.

8.2 Railway Signal Results

Based on the results of the geometric analysis and available imagery, both identified pairs of

railway signals could geometrically experience a solar reflection from the proposed development.

Solar reflections can only occur from a solar panel area which has an unobstructed path to the

signal light.

8.2.1 Light signals 1 and 2

It is expected that the solar reflection modelled for both signals will have a low impact despite

the fact that no screening between the reflective area and the light signals has been identified.

This is because it is expected that the signal light will be surrounded by a hood reducing

significantly the impact.

8.2.2 Light signals 3 and 4

It is expected that the solar reflection modelled for both signals will have a low impact despite

the fact that no screening between the reflective area and the light signals has been identified.

This is because it is expected that the signal light will be surrounded by a hood reducing

significantly the impact.

In conclusion, the predicted solar reflections are not expected to cause a significant safety

concern. However, Pager Power suggests carrying out an on-site assessment to establish if the

signals have hoods or further engagement with Network Rail since it was not possible to establish

it from available imagery.

8.3 Train Driver Results

The analysis showed that a solar reflection is geometrically possible for 27 locations out of 30

considered. However, only for 5 locations the impact is categorised as “moderate” see Figure

1517 (locations 6 to 10), also the solar reflection will affect only train drivers travelling from

Cardiff towards Newport. At these specific locations the solar reflections could last for up to 15

minutes for all observers, however the duration of a solar reflection would be limited by the

speed of the train passing through the solar reflection zone. The model has assumed the whole

solar panel area could produce a specular solar reflection.

17 Source: Aerial image copyright © 2019 Google.


For receptor points between 6 and 10 the reflection will generate within the 8° (left and right)

of the railway bearing18 (see Appendix A). The area is at its minimum at location 6 (only green

area visible - Figure 15 below) and at its maximum at location 10 (green and red areas visible -

Figure 15 below). The solar reflections would also originate from different sections of the

proposed development throughout the days. Some of these reflective sections will be located

within the train driver’s focus.

At all times the solar reflection and direct sunlight will coincide meaning that the train driver will

likely see both the reflecting solar panel area and the Sun. The Sun has a much greater intensity

of light compared to the solar reflection.

A solar reflection could only ever occur when the weather is clear and sunny on the specific

dates and when the Sun has a clear view of the solar panel area i.e. not obstructed by vegetation.

Finally, the train driver workload is a consideration. In this instance the assessed sections of track

are long and straight with four signals but without interchanges or stations where a higher

workload may be anticipated. The expected workload for a train driver on this section of track is

not expected to be above moderate.

Figure 15 – Train driver: observation points which can possibly experience solar reflection

There are similar cases in the UK with solar panels being in close proximity to Railways. One of

these cases is an approved development near Westbury (Figure 16) and Stretham (81Figure 17,

provided by Savills). In the case of Westbury, the proposed development (red line) was located

30 meters from the railway (blue line) with no visible screening. It should also be noted that the

18 This field is considered for signal siting and not as the entire driver’s field of view.


development is located near a railway junction and the train driver workload could be considered

higher compared to the Wentlooge case. The Stretham development is also alongside a railway

line.

Figure 16 – Solar development near Westbury

Figure 17 – Solar development near Stretham


In conclusion, the predicted solar reflections are expected to cause a moderate impact. Previous

cases of developments built alongside railway lines are present in the UK.

8.4 Roads

Based on the review of the analysis for all roads assessed and the available imagery at 59 of the

64 points assessed a solar reflection is geometrically possible.

8.4.1 Ty Mawr Lane

The results for Ty Mawr Lane showed that when a solar reflection is possible, existing screening

will block any reflection coming from the proposed development.

8.4.2 Hawrse Lane

On this road the analysis shows that at 7 of the 15 points assessed a solar reflection is

geometrically possible and unscreened. However, the reflection will originate outside the driver’s

primary field of vision and this road is likely to experience relatively low traffic volumes and

speeds. Also, the reflection and sunlight will always originate from the same location. This means

that the viewer will likely be able to see the glare from the reflecting solar panels as well as the

Sun directly.

In conclusion, the predicted impact is considered “low”.

8.4.3 Broadway


geometrically possible. However, the reflection will originate outside the driver’s primary field of

vision and the driver and this road is likely to experience relatively low traffic volumes and

speeds. Also, the reflection and sunlight will always originate from the same location. This means

that the viewer will likely be able to see the glare from the reflecting solar panels as well as the

Sun directly.


8.4.4 B4239


geometrically possible. However, the reflection will originate outside the driver’s primary field of

vision and this road is likely to experience relatively low traffic volumes and speeds. Also, the

reflection and sunlight will always originate from the same location. This means that the viewer

will likely be able to see the glare from the reflecting solar panels as well as the Sun directly.


8.5 Dwellings Results

Based on a review of the geometric analysis and available imagery, residents located within five

of the 12 assessed dwelling receptors could potentially experience a solar reflection from the

proposed solar development (receptor locations 93, 96, 97, 99 and 100).


Figure 1819 below shows the dwelling receptor locations that could experience a solar reflection

when current screening is considered.

Figure 18 – Dwellings: observation points which can possibly experience solar reflection

19 Copyright © 2019 Google.


Dwelling Dwelling Details/Visibility Comment

93 Views of the reflecting areas are

likely from any floor

Views of the development’s reflecting areas

are likely from any floor considering baseline

conditions.

The reflecting solar panels would be over

100m away.

It is unlikely that existing screening at the

proposed development boundary would

completely eliminate views due to the

proximity of the dwelling to the development.

96 Two storeys

Partial views from first floor only

Views of the development’s reflecting area

are deemed possible considering baseline

conditions.


200m away.



eliminate views.

97 Two storeys

Partial views from first floor only

Views of the development’s reflecting area

are deemed possible considering baseline

conditions.


100m away.



eliminate views.





conditions.


150m away.

No screening identified.


Dwelling Dwelling Details/Visibility Comment





conditions.


150m away.

It is unlikely that existing screening (buildings)

at the proposed development boundary

would eliminate views.

Table 8 – Affected dwellings comments

Overall, a solar reflection may be visible towards up to five dwellings. A view of a solar reflection

from within the assessed dwellings would only occur where there is a clear view of the reflecting

solar panels at the particular time of day when a solar reflection was geometrically possible on a

clear and sunny day. Any solar reflection could last for up to 15 minutes however only when all

of the above criteria are met. In this instance, a resident would also be looking in the general

direction of the Sun. This means that the viewer will likely be able to see the glare from the

reflecting solar panels as well as the Sun directly.

It is important to note that the direct sunlight would be a significantly brighter source of light

when compared to the solar reflection. At any one location, only a particular area of solar panels

will produce a solar reflection towards it, not the whole panel area.

In the event that a solar reflection is experienced by resident within a surrounding dwelling, the

studies presented in Appendix B show how the intensity of a solar reflection from solar panels

compare to those from other common natural and manmade surfaces. The reflectance value of

a solar panel is similar to that of glass and still water and significantly less than that of steel.

At the remaining assessed dwelling receptor locations, no solar reflection is geometrically

possible (receptor locations 101 to 103) or the reflecting solar panel area is not expected to be

visible from the assessed dwelling location due to screening (receptor locations 92, 94, 95 and

98).

In conclusion, the impact toward these dwellings is deemed as moderate and mitigation should

be implemented.


9 OVERALL CONCLUSIONS

9.1 Overview

The results of the analysis show that a solar reflection from the proposed development is

possible.

9.1 Railway Signal conclusions

Four railway signals have been assessed. Based on the results of the analysis, a solar reflection

is deemed possible. However, the impact will be mitigated by the expected presence of a signal

hood. Pager Power suggests carrying out an on-site assessment to establish if the signals have

hoods since it was not possible to establish it from available imagery.

If the on-site assessment establishes that the signals do not have a hood provision of further

screening should be considered. The identified issues are likely to be resolvable and are not

predicted to result in planning refusal.

9.2 Train Driver conclusions

The analysis undertaken considered 30 train driver observer points which cover a total of 3km

of railway. Results and available imagery show that an unscreened geometric reflection is

possible and unscreened for 5 points, but it will only affect trains travelling from Cardiff towards

Newport. For these points, a moderate impact is expected.

9.3 Road conclusions

The analysis carried out considered 64 road driver observer points which cover a total of 6.1km

of road. The results for each road are presented below:

• Ty Mawr Lane: all receptors showed either no reflection possible or sufficient existing

screening is present.

• Hawrse Lane: for receptors where reflection is concurrently possible and unscreened

the impact is categorised as low. Therefore, no mitigation is suggested.

• Broadway: for receptors where reflection is concurrently possible and unscreened the

impact is categorised as low. Therefore, no mitigation is suggested.

• B4239: for receptors where reflection is concurrently possible and unscreened the

impact is categorised as low. Therefore, no mitigation is suggested.

Therefore, no mitigation is suggested.

9.4 Dwellings conclusions

The available imagery showed 12 dwellings requiring assessment, of which moderate effects

were predicted at five. It is estimated that effects could last for 15 minutes per day. These

dwellings are within 200m of the proposed development. These conclusions are based on a

conservative assessment of visibility.


Provision of further screening should be considered.

9.5 Overall Conclusions and Recommendations

With regards to the railway signals Pager Power suggests carrying out an on-site assessment to

establish if the signals have hoods or further engagement with Network Rail since it was not

possible to establish it from available imagery.

The assessment of the proposed development showed that for some of the railway’s observers

the impact is deemed as moderate. The location of the proposed development relative to the

railway line is comparable with similar consented schemes such as those at Westbury and

Stretham (see Section 8.3). These have been in operation for a number of years, demonstrating

the compatibility of solar developments alongside railway lines. Engagement with Network Rail

is recommended to share the results of this assessment and ensure that plans for the

development are communicated in a clear and inclusive fashion.


APPENDIX A – OVERVIEW OF GLINT AND GLARE GUIDANCE

Overview

There is no specific guidance for the assessment of glint and glare from glass windows however

guidance is available for solar photovoltaic developments. The studies in Appendix B state that

solar reflections from these surfaces are similar, and therefore this guidance is presented here

for reference.

An overview of the UK planning policy for solar developments is presented below, as well as the

guidelines with respect to rail travel.

This is not a comprehensive review of the data sources, rather it is intended to give an overview

of the important parameters and considerations that have informed this assessment.

UK Planning Policy

UK Planning Practice Guidance dictates that in some instances a glint and glare assessment is

required, however, there is no specific guidance with respect to the methodology for assessing

the impact of glint and glare.

The planning policy from the Department for Communities and Local Government (paragraph

2720) dictates:

‘Particular factors a local planning authority will need to consider include… the effect on landscape of

glint and glare and on neighbouring uses and aircraft safety.’

The National Planning Policy Framework for Renewable and Low Carbon Energy21 (specifically

regarding the consideration of solar developments) dictates:

‘What are the particular planning considerations that relate to large scale ground-mounted solar

photovoltaic Farms?

The deployment of large-scale solar farms can have a negative impact on the rural environment,

particularly in undulating landscapes. However, the visual impact of a well-planned and well-screened

solar farm can be properly addressed within the landscape if planned sensitively.

Particular factors a local planning authority will need to consider include:

• the proposal’s visual impact, the effect on landscape of glint and glare (see guidance on landscape assessment) and on neighbouring uses and aircraft safety;

20 http://planningguidance.planningportal.gov.uk/blog/guidance/renewable-and-low-carbon-energy/ 21Reference ID: 5-013-20140306, paragraph 13-13,

http://planningguidance.planningportal.gov.uk/blog/guidance/renewable-and-low-carbon-energy/particular-planning-

considerations-for-hydropower-active-solar-technology-solar-farms-and-wind-turbines/


• the extent to which there may be additional impacts if solar arrays follow the daily movement of the sun.

The approach to assessing cumulative landscape and visual impact of large scale solar farms is likely

to be the same as assessing the impact of wind turbines. However, in the case of ground-mounted

solar panels it should be noted that with effective screening and appropriate land topography the area

of a zone of visual influence could be zero.’

Assessment Process

Railway operations are not mentioned specifically within this guidance however it is stated that

a developer will need to consider ‘the proposal’s visual impact, the effect on landscape of glint and

glare and on neighbouring uses…’. Network Rail is a statutory consultee when a development is

located in close proximity to its infrastructure.

No process for determining and contextualising the effects of glint and glare are, however,

provided. Therefore, the Pager Power approach is to determine whether a reflection from the

proposed development is geometrically possible and then to compare the results against the

relevant guidance/studies to determine whether the reflection is significant.

Railway Assessment Guidelines

The following section provides an overview of the relevant railway guidance with respect to the

siting of signals on railway lines. Network Rail is the stakeholder of the UK’s railway

infrastructure. Whilst the guidance is not strictly applicable in Ireland, the general principles

within the guidance are expected to apply.

A railway operator’s concerns would likely to relate to the following:

1. The development producing solar glare that affects train drivers; and

2. The development producing solar reflections that affect railway signals.

Railway guidelines are presented below. These relate specifically to the sighting distance for

railway signals.

Determining the Field of Focus

The extract below is taken from section 3.2 (pages 62-63) of the ‘Guidance on Signal Positioning

and Visibility’22 which details the visibility of signals, train drivers’ field of vision and the

implications with regard to signal positioning.

‘The visibility of signals

3.2.1 Overview

The effectiveness of an observer’s visual system in detecting the existence of a target will depend upon

the object’s position in the observer’s visual field, its contrast with its background, its luminance

properties, and the observer’s adaptation to the illumination level of the environment. It is also

22 Source: Guidance on Signal Positioning and Visibility, December 2003. Railway Group Guidance Note. Last accessed

18.10.2016


influenced by the processes relating to colour vision, visual accommodation, and visual acuity. Each of

these issues is described below.

3.2.2 Field of vision

The field of vision, or visual field, is the area of the visual environment that is registered by the eyes

when both eyes and head are held still. The normal extent of the visual field is approximately 135

degrees in the vertical plane and 200 degrees in the horizontal plane.

The visual field is normally divided into central and peripheral regions: the central field being the area

that provides detailed information. This extends from the central point (0 degrees) to approximately

30 degrees at each eye. The peripheral field extends from 30 degrees out to the edge of the visual

field.

Objects are seen more quickly and identified more accurately if they are positioned towards the centre

of the observer’s field of vision, as this is where our sensitivity to contrast is highest. Peripheral vision

is particularly sensitive to movement and light.

Field of view

In the diagram above, the two shaded regions represent the view from the left eye (L) and the right eye

(R) respectively. The darker shaded region represents the region of binocular overlap. The oval in the

centre represents the central field of vision.

Research has shown that vehicle drivers search for signs/signals towards the centre of the field of

vision. As approach speed increases, drivers demonstrate a tunnel vision effect and focus only on

objects in a field of + 8° from the direction of travel.

3.2.2.1 Relevance

Drivers become increasingly dependent on central vision for signal detection at increasing train speeds,

and even minor distractions can reduce the visibility of the signal if it is viewed towards the peripheral

field of vision. (D I)


Because of our sensitivity to movement in the peripheral field, the presence of clutter to the sides of

the running line, for example, fence posts, lamp-posts, traffic, or non-signal lights, such as house,

factory or security lights, can be highly distracting. (D I)

Implications

Signals should be at a height and distance from the running line that permits them to be viewed

towards the centre of the field of vision. (D)

Signal positioning

‘Car stop’ signs should be positioned such that, if practicable, platform starting signals and ‘OFF’

indicators can be seen in the driver’s central field of vision. (D)

If possible, clutter and non-signal lights in a driver’s field of view should be screened off or removed so

that they do not cause distraction. (D I)

The distance at which the 8° cone along the track is initiated is dependent on the minimum reading

time and distance which is associated to the speed of trains along the track. This is discussed below.

Determining the Assessed Minimum Reading Time

The extract below is taken from section B5 (pages 8-9) of the ‘Guidance on Signal Positioning and

Visibility’ which details the required minimum reading time for a train driver when approaching a

signal.

‘B5.2.2 Determining the assessed minimum reading time

GE/RT8037

The assessed minimum reading time shall be no less than eight seconds travelling time before the

signal.

The assessed minimum reading time shall be greater than eight seconds where there is an increased

likelihood of misread or failure to observe. Circumstances where this applies include, but are not

necessarily limited to, the following:


a) the time taken to identify the signal is longer (for example, because the signal being viewed is one

of a number of signals on a gantry, or because the signal is viewed against a complex background)

b) the time taken to interpret the information presented by the signal is longer (for example, because

the signal is capable of presenting route information for a complex layout ahead)

c) there is a risk that the need to perform other duties could cause distraction from viewing the signal

correctly (for example, the observance of lineside signs, a station stop between the caution and stop

signals, or DOO (P) duties)

d) the control of the train speed is influenced by other factors (for example, anticipation of the signal

aspect changing).

The assessed minimum reading time shall be determined using a structured format approved by the

infrastructure controller.’

The distance at which a signal should be clearly viewable is determined by the maximum speed

of the trains along the track. If there are multiple signals present at a location, then an additional

0.2 seconds reading time is added to the overall viewing time.

Signal Design and Lighting System

Many railway signals are now LED lights and not filament (incandescent) bulbs. The benefits of

an LED signal over a filament bulb signal with respect to possible phantom aspect illuminations

are as follows:

• An LED railway signal produces a more intense light making them more visible to

approaching trains when compared to the traditional filament bulb technology23;

• No reflective mirror is present within the LED signal itself unlike a filament bulb. The

presence of the reflective surfaces greatly increases the likelihood of incoming light

being reflecting out making the signal appear illuminated;

• Many LED signal manufacturers24,25,26 claim that LED signal lights significantly reduce or

completely remove the likelihood of a phantom aspect illumination occurring.

It may therefore be useful to determine the bulb type used in any identified signals, if required.

23 Source: Wayside LED Signals – Why it’s Harder than it Looks, Bill Petit. 24 Source: http://www.unipartdorman.co.uk/Product%20Bulletins/Unipart%20Dorman%20iLS.pdf. (Last accessed

27.02.15). 25 Source: http://www.vmslimited.co.uk/pdf/Rail_LED_colour_light.pdf. (Last accessed 27.02.15). 26 Source: http://alstomsignalingsolutions.com/Data/Documents/Signal_2011_12.pdf. (Last accessed 27.02.15).


APPENDIX B – OVERVIEW OF GLINT AND GLARE STUDIES

Overview

Studies have been undertaken assessing the type and intensity of solar reflections from various

surfaces including glass and is for reference only. An overview of these studies is presented

below.

The guidelines presented are related to aviation safety. The results are applicable for the purpose

of this analysis.

Reflection Type from Solar Panels

Based on the surface conditions reflections from light can be specular and diffuse. A specular

reflection has a reflection characteristic similar to that of a mirror; a diffuse will reflect the

incoming light and scatter it in many directions. The figure below, taken from the FAA guidance27,

illustrates the difference between the two types of reflections. Because glass windows are

(typically) flat and have a smooth surface most of the light reflected is specular, which means

that incident light from a specific direction is reradiated in a specific direction.

Specular and diffuse reflections

27Source: Technical Guidance for Evaluating Selected Solar Technologies on Airports, Federal Aviation Administration,

November 2010.


Solar Reflection Studies

An overview of content from identified solar panel reflectivity studies is presented in the

subsections below. The reflection characteristic is applicable to glass façades as well, such that

this data is considered relevant in the context of this analysis.

Evan Riley and Scott Olson, “A Study of the Hazardous Glare Potential to Aviators from Utility-

Scale Flat-Plate Photovoltaic Systems”

Evan Riley and Scott Olson published in 2011 their study titled: A Study of the Hazardous Glare

Potential to Aviators from Utility-Scale Flat-Plate Photovoltaic Systems28”. They researched the

potential glare that a pilot could experience from a 25 degree fixed tilt PV system located outside

of Las Vegas, Nevada. The theoretical glare was estimated using published ocular safety metrics

which quantify the potential for a postflash glare after-image. This was then compared to the

postflash glare after-image caused by smooth water. The study demonstrated that the

reflectance of the solar cell varied with angle of incidence, with maximum values occurring at

angles close to 90 degrees. The reflectance values varied from approximately 5% to 30%. This is

shown on the figure below.

Total reflectance % when compared to angle of incidence

The conclusions of the research study were:

• The potential for hazardous glare from flat-plate PV systems is similar to that of smooth

water – solar reflections from PV panels are similar to those from glass;

28 Evan Riley and Scott Olson, “A Study of the Hazardous Glare Potential to Aviators from Utility-Scale Flat-Plate Photovoltaic Systems,” ISRN Renewable Energy, vol. 2011, Article ID 651857, 6 pages, 2011. doi:10.5402/2011/651857


• Portland white cement concrete (which is a common concrete for runways), snow, and

structural glass all have a reflectivity greater than water and flat plate PV modules.

FAA Guidance- “Technical Guidance for Evaluating Selected Solar Technologies on Airports”29

The 2010 FAA Guidance included a diagram which illustrates the relative reflectance of solar

panels compared to other surfaces. The figure shows the relative reflectance of solar panels

compared to other surfaces. Surfaces in this figure produce reflections which are specular and

diffuse. A specular reflection (those made by most solar panels) has a reflection characteristic

similar to that of a mirror. A diffuse reflection will reflect the incoming light and scatter it in many

directions. A table of reflectivity values, sourced from the figure within the FAA guidance, is

presented below.

Surface Approximate Percentage of Light

Reflected30

Snow 80

White Concrete 77

Bare Aluminium 74

Vegetation 50

Bare Soil 30

Wood Shingle 17

Water 5

Solar Panels 5

Black Asphalt 2

Relative reflectivity of various surfaces

Note that the data above does not appear to consider the reflection type (specular or diffuse).

An important comparison in this table is the reflectivity compared to water which will produce a

reflection of very similar intensity when compared to that from a solar panel. The study by Riley

and Olsen study (2011) also concludes that still water has a very similar reflectivity to solar

panels.

SunPower Technical Notification (2009)

29 Source: Technical Guidance for Evaluating Selected Solar Technologies on Airports, Federal Aviation Administration, November 2010. 30 Extrapolated data, baseline of 1,000 W/m2 for incoming sunlight.


SunPower published a technical notification31 to ‘increase awareness concerning the possible glare

and reflectance impact of PV Systems on their surrounding environment’.

The figure presented below shows the relative reflectivity of solar panels compared to other

natural and manmade materials including smooth water, standard glass and steel.

Common reflective surfaces

The results show that glass produces a reflection that is of similar intensity to smooth water and

less intense than those of snow and steel.

31 Source: Technical Support, 2009. SunPower Technical Notification – Solar Module Glare and Reflectance.


APPENDIX C – OVERVIEW OF SUN MOVEMENTS AND RELATIVE

REFLECTIONS

The Sun’s position in the sky can be accurately described by its azimuth and elevation. Azimuth

is a direction relative to true north (horizontal angle i.e. from left to right) and elevation describes

the Sun’s angle relative to the horizon (vertical angle i.e. up and down).

The Sun’s position can be accurately calculated for a specific location. The following data being

used for the calculation:

• Time;

• Date;

• Latitude;

• Longitude.

The following is true at the location of the proposed development:

• The Sun is at its highest around midday and is to the south at this time;

• The Sun rises highest on 21 June reaching a maximum elevation of approximately 60-65

degrees (longest day);

• On 21 December, the maximum elevation reached by the Sun is approximately 10-

15 degrees (shortest day).

The combination of the Sun’s azimuth angle and vertical elevation will affect the direction and

angle of the reflection from a reflector. The figure on the following page shows the Sun’s

movement across the sky at the proposed development location. This figure shows the Sun’s

azimuth angle from true north. The high line illustrates the summer solstice (the longest day) and

the lower line illustrates the winter solstice (the shortest day). For all other days in the year, the

Sun would be between this maximum and minimum.


Terrain Sun Curve - From lon: -3.042406 lat: 51.53006

Terrain profile at horizon and sunrise/sunset curve at proposed development location


APPENDIX D – PAGER POWER’S REFLECTION CALCULATIONS

METHODOLOGY

The calculations are three dimensional and complex, accounting for:

• The Earth’s orbit around the Sun;

• The Earth’s rotation;

• The Earth’s orientation;

• The reflector’s location;

• The reflector’s 3D Orientation.

Reflections from a flat reflector are calculated by considering the normal which is an imaginary

line that is perpendicular to the reflective surface and originates from it. The diagram below may

be used to aid understanding of the reflection calculation process.

The following process is used to determine the 3D Azimuth and Elevation of a reflection:

• Use the Latitude and Longitude of reflector as the reference for calculation purposes;

• Calculate the Azimuth and Elevation of the normal to the reflector;


• Calculate the 3D angle between the source and the normal;

• If this angle is less than 90 degrees a reflection will occur. If it is greater than 90 degrees

no reflection will occur because the source is behind the reflector;

• Calculate the Azimuth and Elevation of the reflection in accordance with the following:

o The angle between source and normal is equal to angle between normal and

reflection;

o Source, Normal and Reflection are in the same plane.


APPENDIX E – GLINT AND GLARE IMPACT SIGNIFICANCE

Overview

The significance of glint and glare will vary for different receptors. The following section presents

a general overview of the significance criteria with respect to experiencing a solar reflection.

Impact Significance Definition

The table below presents the recommended definition of ‘impact significance’ in glint and glare

terms and the requirement for mitigation under each.

Impact

Significance Definition Mitigation Requirement

No Impact

A solar reflection is not geometrically

possible or will not be visible from the

assessed receptor.

No mitigation required.

Low

A solar reflection is geometrically

possible however any impact is

considered to be small such that

mitigation is not required e.g.

intervening screening will limit the

view of the reflecting solar panels.

No mitigation required.

Moderate


possible and visible however it occurs

under conditions that do not represent

a worst-case.

Whilst the impact may be

acceptable, consultation

and/or further analysis should

be undertaken to determine

the requirement for mitigation.

Major


possible and visible under conditions

that will produce a significant impact.

Mitigation and consultation is

recommended.

Mitigation will be required if

the proposed development is

to proceed.

Impact significance definition

The flow charts presented in the following sub-sections have been followed when determining

the mitigation requirement for aviation receptors.


APPENDIX F – ASSESSMENT LIMITATIONS AND ASSUMPTIONS

It is assumed that the panel elevation angle (90 degrees) represents the elevation angle for all

reflective surfaces.

It is assumed that the reflector azimuth angle represents the azimuth angle for all of the reflectors

unless stated otherwise.

Only a reflection from the face of the reflector has been considered.

A finite number of points within the proposed development are chosen based on an assessment

resolution so we can build a comprehensive understanding of the entire development. This will

determine whether a reflection could ever occur at a chosen receptor. The calculations do not

incorporate all of the possible reflector locations within the development outline.

The reflection model represents a worst-case analysis because any screening in the form of trees,

buildings etc. have not been considered.

The terrain profile of the horizon has been considered, which may obscure the Sun at its lowest

elevation angles.


Assessment process for Train Driver Receptors

The flow chart presented below has been followed when determining the mitigation requirement

for train driver receptors.

Train driver receptor mitigation requirement flow chart (solar panels)


Assessment Process for Road Receptors


for road receptors.

Road receptor mitigation requirement flow chart


Assessment Process for Dwelling Receptors


for dwelling receptors.

Dwelling receptor mitigation requirement flow chart


APPENDIX G – ASSESSMENT LIMITATIONS AND ASSUMPTIONS

Pager Power’s Model

It is assumed that the panel elevation angle provided by the developer represents the elevation

angle for all of the panels within the proposed development.

It is assumed that the panel azimuth angle provided by the developer represents the azimuth

angle for all of the panels within the solar development.

Only a reflection from the face of the reflector has been considered.

The model assumes that a receptor can view the face of every panel within the proposed

development area whilst in reality this, in the majority of cases, will not occur.

Therefore any predicted reflection from the face of a reflector that is not visible to a receptor

will not occur.

A finite number of points within the proposed development are chosen based on an assessment

resolution so we can build a comprehensive understanding of the entire development. This will

determine whether a reflection could ever occur at a chosen receptor. The calculations do not

incorporate all of the possible panel locations within the development outline.

A single reflection point on the panel has been chosen for the geometric calculations. This will

suitably determine whether a reflection can be experienced at a location and the general time of

year and duration of this reflection. Increased accuracy could be achieved by increasing the

number of heights assessed however this would only marginally change the results and is not

considered significant.

Whilst line of sight to the development from receptors has been considered, only available street

view imagery and satellite mapping has been used. In some cases this imagery may not be up to

date and may not give the full perspective of the installation from the location of the assessed

receptor.

Any screening in the form of trees, buildings etc. that may obstruct the Sun from view of the

solar panels is not considered unless stated.


APPENDIX H – RECEPTOR AND REFLECTOR AREA DETAILS

Roads receptors

The tables below present the assessed roads’ receptor locations. All the road receptors were

considered at a height of 1.5 metre.

Ty Mawr Lane

ID Longitude (°) Latitude (°) Ground

Elevation (amsl)

Overall height

(amsl)

29 -3.061468 51.531357 4.00 5.50

30 -3.060766 51.532143 4.00 5.50

31 -3.060115 51.532946 4.00 5.50

32 -3.059599 51.533776 4.00 5.50

33 -3.059003 51.534596 4.63 6.13

34 -3.058474 51.535423 5.00 6.50

35 -3.058224 51.536316 5.00 6.50

36 -3.057912 51.537181 5.70 7.20

37 -3.057379 51.538026 6.00 7.50

38 -3.056876 51.538857 6.00 7.50

Hawrse Lane


Elevation (amsl)

Overall height

(amsl)

39 -3.040935 51.53941 2.00 3.50

40 -3.039972 51.538734 2.00 3.50

41 -3.03887 51.538173 2.00 3.50

42 -3.037684 51.537676 2.00 3.50

43 -3.036574 51.537106 2.00 3.50

44 -3.035588 51.536474 2.62 4.12

45 -3.034918 51.53568 3.00 4.50

46 -3.034269 51.53488 3.00 4.50



Elevation (amsl)

Overall height

(amsl)

47 -3.03378 51.534041 3.00 4.50

48 -3.033385 51.533178 3.23 4.73

49 -3.03298 51.532318 4.00 5.50

50 -3.032553 51.531436 4.00 5.50

51 -3.032167 51.530641 4.00 5.50

52 -3.031721 51.52972 4.00 5.50

53 -3.031244 51.529233 4.00 5.50

Broadway


Elevation (amsl)

Overall height

(amsl)

54 -3.062623 51.531697 4.00 5.50

55 -3.061315 51.531315 4.00 5.50

56 -3.06039 51.53064 3.00 4.50

57 -3.059538 51.529909 3.00 4.50

58 -3.058603 51.529223 3.00 4.50

59 -3.057397 51.528725 3.00 4.50

60 -3.056384 51.528097 3.00 4.50

61 -3.055387 51.527458 3.00 4.50

62 -3.054365 51.526818 3.00 4.50

63 -3.053315 51.526195 4.00 5.50

64 -3.052279 51.525581 4.00 5.50

65 -3.051229 51.524959 4.00 5.50

66 -3.050179 51.524337 4.00 5.50

67 -3.049143 51.523723 4.00 5.50


B4239


Elevation (amsl)

Overall height

(amsl)

68 -3.029407 51.529743 4.00 5.50

69 -3.030751 51.529386 4.00 5.50

70 -3.031915 51.528883 4.00 5.50

71 -3.033022 51.528323 4.00 5.50

72 -3.03431 51.527898 4.00 5.50

73 -3.035618 51.527492 4.00 5.50

74 -3.036894 51.527097 4.00 5.50

75 -3.038171 51.526701 4.00 5.50

76 -3.039479 51.526296 4.00 5.50

77 -3.040755 51.5259 4.00 5.50

78 -3.042065 51.525451 4.00 5.50

79 -3.04313 51.524966 4.00 5.50

80 -3.044272 51.524447 4.00 5.50

81 -3.04549 51.523892 4.00 5.50

82 -3.046845 51.523604 4.00 5.50

83 -3.048296 51.52356 4.00 5.50

84 -3.049668 51.523326 4.00 5.50

85 -3.050872 51.522941 4.00 5.50

86 -3.052197 51.522557 4.00 5.50

87 -3.053554 51.522164 4.00 5.50

88 -3.054802 51.521783 4.00 5.50

89 -3.056078 51.521387 4.00 5.50

90 -3.057373 51.520966 4.00 5.50

91 -3.058631 51.520548 3.00 4.50

92 -3.059942 51.520057 3.00 4.50


Dwellings Locations


Elevation (amsl)

Overall height

(amsl)

92 -3.059454 51.534649 4.89 6.39

93 -3.058386 51.529635 3.30 4.80

94 -3.040748 51.525612 4.30 5.80

95 -3.037712 51.526578 4.30 5.80

96 -3.033499 51.527877 4.30 5.80

97 -3.031595 51.528748 4.30 5.80

98 -3.030146 51.529244 4.30 5.80

99 -3.032722 51.532252 4.30 5.80

100 -3.034361 51.534554 3.30 4.80

101 -3.04818 51.522315 4.30 5.80

102 -3.052324 51.522084 4.30 5.80

103 -3.054455 51.521718 4.30 5.80

Signal Locations

The details of the receptor points are presented below.

Location Longitude

(°)

Latitude

(°)

Ground and railway line

height

Assessed height

(m)

Light Signal 1 -3.06289 51.52792

The ground height has

been determined by

calculating the ground

heights at the receptor

point. This is based on

OSGB 36 Datum terrain

data.

+ 4m agl


Location Longitude

(°)

Latitude

(°)

Ground and railway line

height

Assessed height

(m)

Light Signal 2 -3.06282 51.52786


been determined by





data.

+ 4m agl

Light Signal 3 -3.04414 51.53667


been determined by





data.

+ 4m agl

Light Signal 4 -3.04408 51.53662


been determined by





data.

+ 4m agl

Information regarding identifed railway signals

Railway signals are estimated to be 4m and 4m tall based on Pager Power’s available imagery32.

32 Source: available imagery copyright © 2019 Google.


Train Driver Receptor Locations

The details of the receptor points are presented below.

Location Longitude (°) Latitude (°) Ground and railway line

height

Assessed height

(m)

1b -3.03660 51.540047


been determined by





data.

+2.75m agl

1a -3.03821 51.539313

1 -3.03966 51.538621

2 -3.04084 51.538079

3 -3.041989 51.537551

4 -3.043137 51.537023

5 -3.044317 51.536481

6 -3.045465 51.535953

7 -3.046645 51.535411

8 -3.047793 51.534883

9 -3.048941 51.534355

10 -3.050121 51.533813

11 -3.051301 51.533271

12 -3.052385 51.532772

13 -3.053533 51.532244

14 -3.054744 51.531687

15 -3.05586 51.531174

16 -3.05704 51.530631


Location Longitude (°) Latitude (°) Ground and railway line

height

Assessed height

(m)

17 -3.058188 51.530104

18 -3.059367 51.529561

19 -3.060515 51.529033

20 -3.061663 51.528505

21 -3.062811 51.527977

22 -3.06399 51.527435

23 -3.065138 51.526907

24 -3.066317 51.526364

25 -3.067465 51.525836

26 -3.068644 51.525294

27 -3.069792 51.524766

28 -3.070971 51.524223

Train driver receptors

Based on previous consultation with Network Rail, the driver’s eye level is assumed to be 2.75m

above rail level33. This height has therefore been added to the ground height34 at each receptor

location.

33 This height may vary based on driver height however this figure is used as the industry standard. 34 The ground height of the railway will likely vary due to manmade raising and lowering of the ground. For the purpose

of this analysis, the heights used are deemed acceptable for determining whether a solar reflection is geometrically

possible. A variation of a small 1-2 metres will not significantly change the results.


Reflector Details

The table below shows the boundary co-ordinates for the modelled solar panela area.

ID Longitude (°) Latitude (°) ID Longitude (°) Latitude (°)

1 -3.05722 51.52962 14 -3.03500 51.52849

2 -3.05401 51.53181 15 -3.03467 51.52796

3 -3.04188 51.53738 16 -3.04252 51.52569

4 -3.04082 51.53677 17 -3.04455 51.52774

5 -3.03882 51.53812 18 -3.04545 51.52720

6 -3.03585 51.53665 19 -3.04330 51.52505

7 -3.03497 51.53550 20 -3.04591 51.52381

8 -3.03635 51.53468 21 -3.04798 51.52381

9 -3.03531 51.53378 22 -3.05034 51.52521

10 -3.03403 51.53423 23 -3.05081 51.52497

11 -3.03182 51.52915 24 -3.05604 51.52809

12 -3.03339 51.52852 25 -3.05554 51.52838

13 -3.03357 51.52888

Bounding reflector co-ordinates


APPENDIX I – GEOMETRIC CALCULATION RESULTS – PAGER

POWER RESULTS

The charts for the receptors are shown on the following pages. Each chart shows:

• The receptor (observer) location – top right image. This also shows the azimuth range of

the Sun itself at times when reflections are possible. If sunlight is experienced from the

same direction as the reflecting panels, the overall impact of the reflection is reduced as

discussed within the body of the report;

• The reflectors – bottom right image. The modelled reflectors are shown. If the reflectors

are not visible from the observer location, no issues will occur in practice. Additional

obstructions which may obscure the reflector area from view are considered separately

within the analysis;

• The reflection date/time graph – left hand side of the page. The blue line indicates the

dates and times at which geometric reflections are possible;

• The red and yellow line show the sunrise and sunset time respectively.

Train Signals Receptors Results

Only the solar reflection charts for receptor locations where a solar reflection has been deemed

possible are presented.


Train Driver Receptors Results

Only the solar reflection charts for receptor locations where a solar reflection has been deemed

possible are presented. Observer 1 and 2 correspond to receptors 1a and 1b, therefore Observer

3 corresponds to receptor 1.


Roads Receptors Results

Only roads receptors where a solar reflection has been deemed possible are presented.

Ty Mawr Lane


Hawse Lane


Broadway


B4239


Dwellings Receptors Results

Only dwellings where a solar reflection has been deemed possible are presented.

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