TRAFFIC IMPACT ASSESSMENT FOR THE PROPOSED … - Panorama... · traffic impact assessment for the...

TRAFFIC IMPACT ASSESSMENT

FOR THE PROPOSED

PANORAMA BUSINESS PARK

PIETERMARITZBURG

Revision 2

NOVEMBER 2011

PREPARED FOR: PREPARED BY:

ASG Properties Pietermaritzburg Report No R2011/17/P0099

(i)

R2011_17_P0099 Panorama Business Park TIA_Rev2.doc

TABLE OF CONTENTS

Page No.

1. INTRODUCTION ......................................................................................................................... 1

2. THE PROPOSED DEVELOPMENT ................................................................................................ 1

3. EXISTING AND FUTURE TRAFFIC SITUATION ........................................................................... 1

4. TRIP GENERATION AND DISTRIBUTION ................................................................................... 3

5. TRAFFIC IMPACT ....................................................................................................................... 4

6. SUMMARY OF RECOMMENDATIONS .......................................................................................... 6

7. CONCLUSIONS ........................................................................................................................... 6

1


1. INTRODUCTION

David McFarlane and Associates cc were requested by ASG Properties to prepare a traffic

impact assessment report for the proposed Panorama Business Park in Pietermaritzburg. This

report documents the findings of this assessment.

2. THE PROPOSED DEVELOPMENT

The proposed is situated on Portion of the Rem of ERF 783 Panorama Gardens in

Pietermaritzburg with access off Birmingham Road, as shown in Figure 1. The property is some

11.8 Ha in size. The proposed layout and zonal controls are as shown on Figure 2.

The largest single site on the property is general/commercial and is seen as being low impact

retail. The majority of the site is to be zoned as General. This allows for a wide range of

possible types of land uses. The best estimate at this time is likely to be 50% industrial, 25%

offices and 25% low impact retail.

3. EXISTING AND FUTURE TRAFFIC SITUATION

The existing peak hour traffic volumes in the vicinity of the site are as shown on Figures 3 and 4

for the AM and PM peaks respectively. These are made up from recent counts along New

Greytown Road (September 2011) and older counts from 2007 [prior to construction of the N3

Church St/Greytown interchange commencing] along Old Greytown road between Masukwana

Street and Otto’s Bluff Road. This option was taken as it was felt that counting traffic while

under construction is difficult and traffic patterns are likely to be distorted.

To interpret the current traffic patterns and likely future traffic patterns, one needs to consider

the history of this area and the road infrastructure currently under construction.

Historically, the N3 Church St/Greytown interchange was highly congested during commuter

peaks. The main movements in the AM peak are from the east along Old Greytown road to both

the west [Pietermaritzburg CBD] and the north on the N3, with the reverse in the PM peak. The

traffic demand far exceeded the capacity of the interchange, and hence major distortions of the

traffic patterns have occurred [as clearly evident in the traffic counts] as expanded on below:

• For a road network with sufficient capacity, one would expect the PM peak traffic patterns

to be close to the inverse of the AM peak, which in this case is not so. The existing patterns

indicate that the AM peak congestion is worse than the PM peak congestion.

• Traffic from the west on Old Greytown road peaks very early the morning, typical when

commuters leave early to avoid congestion.

• There is clear evidence of deviations to avoid congestion [often called “rat running”],

particularly in the AM peak, less so in the PM peak. The largest of these is along Allendale

Drive, right into New Greytown Road then left into Ohrtmann Road, a movement not

reflected as strongly in the PM peak [but does occur to a lesser degree].

2


Due to this congestion being experienced, SANRAL are currently constructing a major upgrade

to the N3 Church St/Greytown interchange. The main elements of this upgrade include the

following:

• Free flow directional ramps from east to north and west to north.

• Additional through lanes east to west and west to east from Masukwana Street to Otto’s

Bluff Road. This entails new/widened bridges over the N3 and a steam near Masukwana

Street.

• Introduction of a west to south turning lane at the eastern terminal.

• Du Toit Viljoen Road to the east of the eastern terminal to become left-in left-out only.

Once these upgrades are complete, we believe the following changes to the traffic patterns will

occur:

• The current “rat runs” on Allendale/New Greytown/Ohrtmann will use Old Greytown road.

• Less peak spreading east to west along Old Greytown Road [AM peak].

• Latent/induced demand. With major capacity upgrades, additional traffic is normally found

due to elimination of congestion.

The main impacts of these changes to the traffic patterns are felt to be:

• Free up available capacity along New Greytown road, Ohrtmann road and Manning/Larch

road.

• In any road network, there will always be a “weak link” or system capacity constraint. With

the major capacity upgrade along Old Greytown road from Otto’s Bluff road to Masukwana

Street, the system capacity constraint will no longer be in this section of the road network,

and will shift to other locations in the network. For our area of impact, the section of Old

Greytown road from Otto’s Bluff to New Greytown road is of concern as this is not part of

the SANRAL upgrade and could become the system capacity constraint. This is explored

further below.

Given the timing of the proposed Panorama Business Park, which will be operational only once

the construction currently in progress has been completed, this assessment has been based on

the predicted change to current traffic patterns rather than that being experienced today. The

road upgrades currently in progress by SANRAL will provide huge additional capacity, designed

to cater for the long term capacity needs in this area, and hence our focus was not on these

new upgraded intersection, rather the impact this will have on changing traffic patterns and the

impact beyond their limit of construction. Based on this logic, the following intersections were

the main focus of this investigation:

• New Greytown/Birmingham

• New Greytown/Ohrtmann

• New Greytown/Old Greytown

• Old Greytown/Otto’s Bluff

3


Based on the above arguments, the predicted revised traffic patterns through the above

intersections [as used in this assessment] are as shown on Figures 5 and 6 for the AM and PM

peaks respectively. The assumed adjustment to the traffic patterns are as highlighted in blue.

4. TRIP GENERATION AND DISTRIBUTION

The estimated trip generation for the proposed Panorama Business Park are as shown on

Tables 1 and 2 for the AM and PM peak hours respectively.

Based on current traffic patterns, the assumed distribution of trips is as shown below:

From/to Old Greytown Road south = 40%

From/to Old Greytown Road north = 5%

From/to Allendale Road = 20%

From/to New Greytown Road east = 10%

From/to Birmingham Road south = 5%

From/to Ohrtmann Road south = 20%

TA

BLE

1:

AM

PE

AK

TR

IP G

EN

ER

AT

ION

AS

SU

ME

DT

RIP

FLO

OR

AR

EA

(m2

)R

AT

EIN

OU

TIN

OU

T

GE

NE

RA

L/C

OM

ME

RC

IAL

41

,64

51

2,0

00

LOW

IM

PA

CT

RE

TA

IL2

.0/1

00

m2

50

%5

0%

12

01

20

15

,00

0IN

DU

ST

RIA

L0

.9/1

00

m2

75

%2

5%

22

57

5

7,5

00

LOW

IM

PA

CT

RE

TA

IL2

.0/1

00

m2

50

%5

0%

75

75

7,5

00

OF

FIC

ES

2.3

/10

0m

28

5%

15

%1

28

23

INT

ER

NA

L T

RIP

S1

5%

-83

-43

TO

TA

L4

65

25

0

TA

BLE

2:

PM

PE

AK

TR

IP G

EN

ER

AT

ION

AS

SU

ME

DT

RIP

FLO

OR

AR

EA

(m2

)R

AT

EIN

OU

TIN

OU

T

GE

NE

RA

L/C

OM

ME

RC

IAL

41

,64

51

2,0

00

LOW

IM

PA

CT

RE

TA

IL3

.0/1

00

m2

50

%5

0%

18

01

80

15

,00

0IN

DU

ST

RIA

L0

.9/1

00

m2

25

%7

5%

75

22

5

7,5

00

LOW

IM

PA

CT

RE

TA

IL3

.0/1

00

m2

50

%5

0%

11

31

13

7,5

00

OF

FIC

ES

2.3

/10

0m

21

5%

85

%2

31

28

INT

ER

NA

L T

RIP

S1

5%

-61

-96

TO

TA

L3

30

55

0

TR

IPS

GE

NE

RA

L 6

6,3

73

GE

NE

RA

L 6

6,3

73

ZO

NIN

GLA

ND

AR

EA

(m

2)

LAN

D U

SE

SP

LIT

ZO

NIN

GLA

ND

AR

EA

(m

2)

LAN

D U

SE

SP

LIT

T

RIP

S

4


5. TRAFFIC IMPACT

Based on the assumed redistribution of trips [as shown in Figures 5 and 6] due to the N3

interchange upgrade currently in progress, the four critical intersections were analysed [using

the SIDRA programme] initially without the additional traffic due to the proposed Panorama

Business Park (PBP) and then with the additional traffic due to the proposed Panorama Business

Park. The results of this analysis are summarised in Table 3 and discussed further below.

TABLE 3: INTERSECTION CAPACITY ANALYSIS

INTERSECTION TIME

PERIOD

PBP

TRAFFIC

OVERALL I/S WORST MOVEMENTS

DELAY LOS V/C DELAY LOS

New Greytown

/Birmingham

AM NO 17.6 B 0.41 33.2 C

YES (1) 23.9 C 0.70 39.4 D

PM NO 17.5 B 0.40 28.9 C

YES (1) 20.9 C 0.58 40.3 D

New Greytown

/Ohrtmann

AM NO 15.9 B 0.53 30.6 C

YES 19.9 B 0.79 41.9 D

PM NO 18.6 B 0.78 48.1 D

YES 27.3 C 0.92 62.2 E

New Greytown

/Old Greytown

AM NO (1) 15.1 B 0.80 36.2 D

YES (1) 16.4 B 0.80 36.3 D

PM NO (1) 12.1 B 0.58 59.9 E

YES (1) 13.6 B 0.62 63.7 E

Old Greytown

/Otto’s Bluff

AM NO (1) 26.4 C 0.85 77.4 E

YES (1) 27.2 C 0.86 77.4 E

PM NO (1) 21.7 C 0.83 93.2 F

YES (1) 22.3 C 0.87 101.4 F

(1) Intersection Modified

New Greytown/Birmingham

The New Greytown/Birmingham intersection will be highly impacted on as most of the traffic

attracted to the proposed Panorama Business Park will pass through this intersection. In order

to accommodate this additional traffic, modifications to both the geometric layout and signal

setting will be required. The suggested geometric improvements is as shown on Figure 7, being

a south to west left turn lane. The signals would also need to provide a right turn green arrow

phase for right turners from west to south (New Greytown from the west turning right into

Birmingham). Provided these improvements are in place, conditions at this intersection are

indicated as acceptable.

5


New Greytown/Ohrtmann

At the New Greytown/Ohrtmann intersection, conditions will worsen marginally with the

additional traffic due to the Proposed Panorama Business Park. All movements are indicated at

LOS D or better except a minor movement at LOS E, which is considered to be acceptable.

New Greytown/Old Greytown and Old Greytown/Otto’s Bluff

At both the New Greytown/Old Greytown and Old Greytown/Otto’s Bluff intersections, it was

found that if the reassigned traffic demands [as shown on Figures 5 and 6] were analysed on

the existing layouts even without the additional traffic due to the proposed Panorama Business

Park, conditions were indicated as poor. In other words, these intersections are indicated as

becoming a bottleneck in the system once the interchange upgrade currently in progress is

completed.

In discussions with others involved with the interchange upgrade, it was confirmed that this

issue had been recognised and brought to the attention of SANRAL by the local Municipality.

SANRAL, however, are not willing to fund road works beyond the current limits of construction

and considers this to be the responsibility of the local Municipality, with this not as yet fully

resolved.

Within the limitations of this assessment, it was found that if an additional through lane is

added in both directions [3+3 lanes rather than the current 2+2 lanes], conditions become

acceptable, being the outputs as shown in Table 3 above. The very poor LOS shown is for very

minor movements only.

When the additional traffic due to the proposed Panorama Business Park was added, conditions

change only marginally, as shown in Table 3 above. This is because the additional traffic due to

the proposed Panorama Business Park is only a small increase over the existing demand

[approximately 7%] and it only impacts marginally on the critical intersection movements.

Access to the Development off Birmingham Road

Birmingham road in the vicinity of the proposed access to the Panorama Business Park is over

10 metres in width. It is recommended that a right turn refuge lane be provided for the

proposed access by remarking/repainting the road surface. In addition, a left turn slip into the

development from the north is also recommended so as not to delay southbound traffic on

Birmingham road.

For the access road within the property, we recommend one lane in and one lane out be

provided within the development. This needs to be developed in more detail as the planning for

the development progresses.

A priority (stop controlled) access onto Birmingham road will be adequate.

6


6. SUMMARY OF RECOMMENDATIONS

In summary, the following is recommended to mitigate the impact of the proposed Panorama

Business Park:

1. Improvements to the geometrics of the New Greytown/Birmingham intersection as shown

on Figure 7, being a south to west left turn lane. The signals would also need to provide

a right turn green arrow phase for right turners from west to south (New Greytown from

the west turning right into Birmingham).

2. No changes to the New Greytown/Ohrtmann intersection.

3. Indications are that both the New Greytown/Old Greytown and Old Greytown/Otto’s Bluff

intersections will require an additional through lane in both directions [3+3 lanes rather

than the current 2+2 lanes] once the N3 interchange are completed based on the current

demand alone. When the additional traffic due to the proposed Panorama Business Park

is added, conditions change only marginally. This is because the additional traffic due to

the proposed Panorama Business Park is only a small increase over the existing demand

[approximately 7%] and it only impacts marginally on the critical intersection movements.

4. Access to the proposed Panorama Business Park off Birmingham road should be stop

controlled with a right turn refuge lane provided on Birmingham road within the existing

road width and a left turn slip road into the development. For the access road within the

property, we recommend one lane in and one lane out be provided within the

development.

7. CONCLUSIONS

Provided the various recommendations, as listed in section 6 above are implemented, the

proposed Panorama Business Park should be allowed to proceed (from a traffic impact

viewpoint only).

__________________

D G McFarlane Pr Eng

PANORAMA BUSINESS PARK

FIGURE 1 : LOCALITY PLAN

FIGURE 3 : EXISTING AM PEAK HOUR TRAFFIC

FIGURE 4 : EXISTING PM PEAK HOUR TRAFFIC

FIGURE 5 : REASSIGNED AM PEAK HOUR TRAFFIC

FIGURE 6 : REASSIGNED PM PEAK HOUR TRAFFIC

S G OEXISTING LAYOUT

FIGURE 7 : NEW GREYTOWN/BIRMINGHAM INTERSECTION

PROPOSED LAYOUT

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