The NSG is a centralised unique referencing system, designed to improve the relationship between local authorities and utilities. Its fundamental aim is to make the street works process more convenient to the citizens who use them.
Streets are part of the country's infrastructure through which many citizen centred services are provided. Consequently there are a range of street related issues such as congestion, capacity planning, street works, accidents, incidents and maintenance which affect them. A core dataset which records all of these issues, and their attributes is essential.
The National Street Gazetteer (NSG) is the definitive reference system used in the notification process and the coordination of street works. Under legislation, each local highway authority in England and Wales is required to create and maintain its own Local Street Gazetteer (LSG) and Associated Street Data (ASD). These are then compiled into the only master index built to the national standard BS 7666, for access by a number of other organisations via the NSG online hub and managed by GeoPlace.
Required under the New Roads and Street Works Act (1991), the NSG contains more than 1 million streets. It is an unambiguous referencing system, using Unique Street Reference Numbers (USRNs) to identify any length of highway or road in England and Wales. Set up initially to improve highway maintenance, the NSG enables local authorities to coordinate activities and the utilities to know where and when to dig holes.
On a monthly basis, all 174 highway authorities across England and Wales upload their LSGs, along with ASD, to the NSG hub. This enables third party organisations such as public utilities to meet their highway statutory requirements to provide the appropriate street works notifications. Local authorities are required to provide monthly updates.
The legislation requires that all publicly maintained highways, prospective publicly maintained roads, as well as private roads are recorded in the National Street Gazetteer.
The following types of streets are included in the NSG:
- classified principal streets including trunk roads and other classified numbered streets
- other publicly maintained unclassified numbered streets
- prospective publicly maintained streets
- private streets known to the highway or roads authority
- remote footpaths
- subways that are publicly maintained
- maintained or mettalled footpaths.
Who can use the NSG
The NSG can only be used by an organisation with a statutory duty to coordinate street works activities or dig in the road or a legitimate need to access the data connected to the core business function of an organisation contributing data to and from the NSG.
What information does the NSG contain?
The NSG contains a range of street network and related information including:
- street name and location details
- street geometry
- Additional Street Data (ASD).
What is Additional Street Data?
Additional Street Data includes:
- details of ownership
- reinstatement categories
- details of protected streets
- special designations such as
- traffic sensitive streets
- streets with special engineering difficulties
- level crossing safety zones
- environmentally sensitive areas
- streets with special surfaces
- streets with priority lanes
- streets with special construction needs
- height, weight and width restrictions
- direction restrictions.
What is the NSG being used for?
Under the present legislation, the NSG enables highways authorities and statutory undertakers to coordinate street works in order to ease traffic congestion and disruption to road users.
The detailed street information helps the utilities to accurately pinpoint the location of their proposed works and the ASD gives them advance notice of any restrictions that may be in force on that street at any particular time. At present, over 660 organisations are able to use the NSG to manage street related activities on over 1,178,000 streets in England and Wales.
What is the NSG's relationship to NLPG?
A local authority's LSG and LLPG will have synchronicity of all street types, level 3 geometry and working relationships between the street naming and numbering function and LLPG processes, and the highways function.
Whilst a unitary authority will be responsible for both gazetteers, making it easier to achieve continuity of streets data, the same is not the case for counties and districts. These organisations need to have processes in place to work through the anomalies in order to ensure continuity.
Street data continuity becomes important as more organisations begin to use the gazetteers for mission critical applications. Collaboration between counties and districts is facilitated if all parties communicate about the same properties on the same street using the same unique reference. Flood alleviation is a good example because flood extents can be described by both street and property.
NSG - supporting the Traffic Management Act (TMA)
The aim of the TMA is to reduce road congestion, improve journey times and coordinate street works for the benefit of road users. Information contained in the NSG helps provide the basis for highway authorities to manage all TMA related processes and allows statutory undertakers to be aware of protected or traffic sensitive streets, and streets with special engineering difficulties. In effect, the NSG reduces the impact of street works to the citizen as the new legislation empowers the highway authority to have more control over their own street network.