Migrating to a National Street Gazetteer based on the

Digital National Framework

Dave Simmons

David C Simmons GIS Consultants

- May 18th 2005

Working for GIS-based interoperability

The National Street Gazetteer

A Grand Vision for Highways Management

The NSG Vision

• That each highways authority would maintain a local street gazetteer (LSG).

• That at regular intervals, the gazetteers from every highway authority would be combined to form a national gazetteer of streets (the NSG).

• That associated street data (ASD) would be recorded for each NSG street.

• And that this could form the basis for all highway-related administration...

NSG: A Big Effort... (but limited success)

• USRN based referencing does not locate streetworks precisely.

• USRN referencing does not produce a seamless national network

• The USRN base limits the potential value of ASD and makes it difficult to maintain.

• Local management of ESUs (level 3) means that in practice, they cannot be aggregated and published nationally.

Urban Area: 53 ESUs making up one USRN

This ESU can easily be given a description...

An ESU/Link reference gives a better location

In Addition, NLPG guidance leads to...

• Type 1 non-highway streets that may or may not be “official named roads”;

• Named streets that are split at unmappable and fuzzy “locality boundaries”;

• ESUs aggregated arbritrarily to produce aesthetic “street through village” descriptions;

• etc...

Rural Area: 3 USRNs sharing 1 access ESU

…And Elsewhere in Highways IT

• UKPMS survey results are difficult to relate to the NSG, and even more difficult to compare with other survey results – you only get printed overlays (if you are lucky!)

• Road maintenance inspections are difficult to map, relate to NSG and publish – many Highway Authorities are still struggling to “build a network”

• …due to no standardised base network approach.

The Evidence

• Robert James report to DfT• Robin Waters Acacia report 2• Halcrow

– difficulty aggregating LSGs across Highway Authorities

• S.E Water– regional utilities have to cope with divergent LSGs

• ETON developers group - “poor basis for ASD”• EMPRESS - communication issues between street

naming and highways contributing to limitations.• Dave Simmons AGI 2003 paper

The Digital National Framework (DNF)

Evolving a framework for interoperability across all kinds of information.

What is DNF?

• DNF is a description of best practice which maximises the potential of geospatial data.

• Principles and methods rather than an explicit standard.

The aim …

To avoid unnecessary duplication and redundancy, and to increase the interoperability of Geographic Information.

DNF Principles of Best Practice…

• Never capture data if it already exists.• Data should be captured at the largest, most

detailed scale possible.• Create “composite” features from existing features

wherever possible.• If you create “new” data establish unique

identifiers for each feature.• Locate information to the National GPS Network.• Publish & distribute data in a common format.

Digital National Framework - Structure

Base ReferenceInformation

ApplicationInformation

AssociatedReference Information.

}

}

}

“DNF is primarily concerned with geospatial information and its relationship to other data and information”

} Geodetic Reference System

Highways Management in Oxfordshire

Putting DNF Principles into Practice

Before DNF, Oxfordshire had...

• A locally digitised network–out of step with Ordnance Survey data.

• LLPGs increasingly generating conflicting streets.• Poor communication between county/districts.• No common county/district GIS base.• Drift between UKPMS, EXOR, NSG networks

making it very difficult to achieve good asset recording and interoperability.

...Yet resource intensive in both district and county.

The Integrated Transport Network (ITN)

• Ordnance Survey, the national mapping agency, currently produce a detailed transport network which is available to all local authorities.

• It is high quality, nationally consistent, and already linked with other OS data.

• As well as road links (ESUs), ITN contains junctions, restrictions and routing information.

• Named roads, numbered roads, and trunk roads are all present.

• It is the ideal candidate for DNF base reference information!

The Benefits of Linking NSG to ITN

• Link level (ESU) junction-to-junction precision.• Nationally consistent geography for highways.• National “anonymous” identification (TOID).• Consistent with and linked to underlying

topography.• Properties associate with ITN links for service

connection, access and emergency routing.• ITN includes traffic restriction and routing

information.• One network base for all purposes!

Building the DNF NSG using ITN

• Separate genuine highway streets from “property street placeholders”

• Create "ESUs" from ITN (using it as a DNF Base Reference Network).

• Identify them using ITN TOID (identifier).• Formalise communication between districts and

county highways departments.• Cooperate with OS to improve ITN (using local

input allied with strict OS Survey Rules)• Use improved ITN to identify all Highway Streets

*Note: BS7666 revision is encouraging cross-referencing and classification

TOID/Ref Number

After DNF- Relationships to Topographic and ITN layers

Oxfordshire – The Results (so far…)

• Streetworks location queries at a low level.• Better location possible (see Mayrise example).• Struggling with local digitising is eliminated.• Good relationships with districts now that ITN-

NSG forms a sound common base that fits with MasterMap and Land-line.

• District LLPGs improving on a sound base.• ITN has been improved through feedback to OS.• ITN network poised to provide interoperable

linear networks for maintenance and UKPMS.

Using the DNF NSG and property linksto locate streetworks using text in the notice

Screenshot courtesy of Mayrise systems

Oxfordshire Integrated GIS

Potential Stages in a National Migration of Highways IT to a DNF base

• Use Oxfordshire migration path – separate highway and property – cross-reference to ITN.

• Having established a 1:1 relationship of USRN to ITN TOID…– We could communicate through ITN TOIDs instead

• Having modified software to “speak TOID”…– We could Expand TOID role to ESUs (link toids),

junctions (node toids) surface (road polygon toids)

• Allow “user TOIDs” (such as gas pipeline TOIDs).• Build highway linear networks from the same ITN

base...

Sample DNF Interoperability Advantages

• Traffic counts (eg. from UTC) could help set streetworks reinstatement categories

• UKPMS visual survey details could help public information on road condition...

• Street lighting, road defect and street works information could integrate readily with CRM

• Construction details (used in Deflectograph lifetime calculations) could be more generally available

Where Now for Interoperability ?

• Change is needed

• Radical Change is possible

• Oxfordshire have done it – others in the pipeline

• It can be done nationally

• It will cost far less than “continuing as we are”

Summary - What is needed ?

• Highway streets clearly distinguished from ”property address streets” (BS7666 revision would be helpful)

• DNF – coherent and consistent national identification and pervasive use of GIS – ITN - for street links

– Buried services working group - for utility service links

• Link (ESU) level management• A convincing migration strategy• DfT backing and well-informed central coordination

Questions?

Dave Simmons

David C Simmons GIS Consultants

www.highwaymapper.co.uk

The Digital National Framework: www.dnf.org