Data Sources & Provenance

Summary table

Dates are when the extract was taken for CivilsRoute; the underlying datasets are refreshed on their own schedules (the NH Network Model, for example, updates daily). Every dataset is released under the Open Government Licence v3.0 — the region-boundary layer carries an additional OS attribution requirement, shown in the Licence column below.

Dates are shown to the precision recorded at the time of extraction. NH Structures was obtained via an FOI/EIR request rather than an open-data portal, so — consistent with National Highways' usual response practice — it's dated to calendar year only; Marker Posts predates our current extraction-logging convention and is likewise shown to year precision. Neither reflects a gap in the underlying records. *National Cycle Network: Sustrans (now Walk Wheel Cycle Trust) publishes this data under OGL v3.0, but asks that re-publication be confirmed with them directly — see the National Cycle Network section. A&E Hospitals and Police Force HQs are compiled point lists, not a single open-data extract — see the note below before relying on them. †The National Highways live feeds are supplied through its developer portal under the portal’s own terms and conditions rather than a stated Open Government Licence — see the section below. ‡The Laybys and Truck Stops items carry no licence line of their own; the survey they come from is published under the Open Government Licence — see the section below.

NH Structures

*_Structures.csv — National Highways' inventory of structures on the Strategic Road Network: overbridges, underbridges, footbridges, retaining walls, culverts, sign and signal gantries, CCTV masts and similar. Each record carries a structure reference (STR_…), type and subtype, the road, the maintenance area and a region tag.

Detailed inspection and assessment records are not open data — those are obtained from National Highways under a project information protocol. This layer is asset locations and classifications only.

Road Network

network_*.json — the Network Model (Public): a link-and-node model of England's Strategic Road Network with road numbers, carriageway form, direction, lane counts, junction references and a What3Words tag per link. It is the geometry behind the "Road Network (Lines)" layer.

Red Line Boundary

boundary_*.json — the RedLine Outline (Operational Highway Boundary): the polyline outline of the land that belongs to the highway for the whole SRN. It is the geometry behind the "Red Line Boundary" layer.

Diversion Routes

Diversion Routes are the agreed alternative routes National Highways uses when part of the Strategic Road Network is closed, with their closed sections and points of interest such as height, width and weight restrictions. The layer is requested live from National Highways’ public ArcGIS service. The routes shared are limited to those implemented for unplanned events.

Diversion routes are indicative. Check the current arrangements with National Highways before relying on one.

Scheduled Road Closures

The Scheduled Road Closures (NH) layer shows National Highways’ planned road closures on the Strategic Road Network, with the road, type and nature of the works and the scheduled start and end times. It is requested live from National Highways’ public ArcGIS service, which is updated daily, and only closures that have not yet ended are shown.

Planned dates change. Check with National Highways before relying on a closure.

Link Speed & Delay (Travel Time Reporting Tool)

ttrt_nh.json and ttrt-report.html — the Link Speed & Delay (NH) layer shows, for each Strategic Road Network link, the posted speed limit, average, median and 85th percentile speed, average and unexpected delay, daily flow and the AM, interpeak, PM and overnight figures for 2024/25. The full report page for a link (all years from 2020/21 and day types) is requested live from National Highways’ public ArcGIS service. The data is a summary of RIS2 metrics from National Highways’ Travel Time Reporting Tool, version 2.5.6.

Figures are link-averaged and indicative. They are not a speed survey at a point, and the 85th percentile is taken across each link’s average speeds, not individual vehicles. Confirm against surveyed speeds before using them for design. Strategic Road Network only.

Marker Posts

*_markerposts.csv — Strategic Road Network Marker Posts: the driver location signs installed along the SRN, nominally at 100 m intervals, each with a post reference (P…), section name, road, direction and maintenance area. It is the "Marker Posts (100m)" layer.

Coverage is roughly 100% of motorways, ~55% of dual-carriageway A-roads and ~25% of single-carriageway A-roads — driver location signs were rolled out mainly on high-speed roads, so a single-carriageway trunk A-road legitimately shows no marker posts.

Water Quality Priority Locations

outfalls.json — National Highways' Water Quality Plan 2030 confirmed high priority locations: the outfalls and soakaways confirmed as priorities for new or upgraded treatment by the end of the 2030/31 financial year. These are drawn from National Highways' wider assessment of 1,236 outfalls and soakaways judged potentially at high risk of polluting the environment around the network, of which up to around 250 are ultimately expected to need new or upgraded treatment — the current list is that flagged subset, not the full 1,236-location inventory. Each point carries an asset reference, the road, the receiving waterbody, a delivery status, and a mitigation-scope status (WQP_Mitigation). This is a water-quality mitigation scheme tracker, not a general drainage asset inventory; the much larger drainage-and-geotechnical asset dataset National Highways holds internally (condition scores, pipework, cuttings and embankments) is a separate dataset, obtained separately and not yet part of any CivilsRoute layer. The list has changed substantially since the October 2025 publication, not simply grown: 108 of the original 182 locations carry over unchanged, 74 were removed, and 142 further locations were newly identified or reprioritised in, bringing the current total to 250. National Highways' stated reasons for removal are a mix of genuine resolution — existing treatment identified, or the site already being addressed under a separate scheme — and rescoping, most commonly a location being deprioritised following further assessment, or found not to drain a highway or not to be a National Highways asset in the first place. National Highways publishes the removed/reprioritised locations as a companion list, with a reason recorded against each one. This is the "Drainage Constraints (Outfalls)" layer.

Refreshed 11 September 2026 to National Highways' updated publication of 250 confirmed high priority locations, replacing CivilsRoute's original extract of the October 2025 publication (182 locations).

Crash Data (STATS19)

*_crashes.csv — the Department for Transport's Road Safety Data: the statutory STATS19 record of every personal-injury road collision in Great Britain, with severity, date, road and junction detail, conditions, and vehicle/casualty counts. The CivilsRoute extract covers collision years 2020–2024. It is the "Crash Data" / STATS19 layer.

Standard STATS19 caveats apply: slight injuries are under-reported, severity reporting changed with injury-based systems around 2016–2019 (the extract keeps DfT's adjusted-severity estimates), and coordinates are approximate.

Flood Zones

flood_*.json — the Environment Agency's Flood Map for Planning, simplified to Flood Zone 2 and Flood Zone 3 polygons with a fluvial / tidal source tag (flood_zone, flood_source). It is the "Flood Zones" layer.

The Environment Agency retired the separate Flood Zone 2 and Flood Zone 3 datasets in 2025 and replaced them with a single "Flood Map for Planning — Flood Zones" product; the CivilsRoute extract preserves the FZ2 / FZ3 distinction. Flood Zones do not account for defences — always check the current EA map for a live scheme.

Habitats

habitats_*.json — Natural England's Priority Habitats Inventory (England): the spatial inventory of habitats of principal importance under Section 41 of the NERC Act 2006, mapped to polygons with a main-habitat name and code (MainHabs, HabCodes — e.g. Deciduous woodland / DWOOD). It is the "Protected Habitats" layer.

SSSI, SPA & SAC

sssi.json — Sites of Special Scientific Interest (England): land notified under the Wildlife and Countryside Act 1981 as nationally important for its wildlife, geology or landform. spa.json — Special Protection Areas (England): sites classified under the Birds Directive for rare and vulnerable birds. sac.json — Special Areas of Conservation (England): sites designated under the Habitats Regulations for habitats and species of European importance. These are the "SSSI", "Special Protection Areas" and "Special Areas of Conservation" layers.

Ancient Woodland

woodland.json — Natural England's Ancient Woodland Inventory (England): land continuously wooded since at least 1600 AD, covering Ancient Semi-Natural Woodland, Plantation on Ancient Woodland Sites and Ancient Wood Pasture. It is the "Ancient Woodland" layer.

AONB, National Parks & Scheduled Monuments

aonb.json — Areas of Outstanding Natural Beauty (England), now rebranded National Landscapes. parks.json — National Parks (England) boundaries. Both are Natural England designations, not Historic England — the in-app layer labels currently say "Historic England" for these two, which is being corrected to Natural England. monuments.json — Scheduled Monuments, from Historic England's National Heritage List for England (NHLE), which is correctly attributed to Historic England. These are the "Areas of Outstanding Beauty", "National Parks" and "Scheduled Monuments" layers.

Air Quality Management Areas (AQMA)

aqma.json — Air Quality Management Areas: the boundaries local authorities have declared under Part IV of the Environment Act 1995 where one or more national air quality objectives is not expected to be met, and which the authority must address in a formal Air Quality Action Plan. Each polygon carries a name, an AQMA reference, the declaring local authority's ONS code, and a documentation link to Defra's UK-AIR register entry for that AQMA. It is the "Air Quality Management Areas" layer.

AQMA boundaries are declared and revoked by individual local authorities on their own timescales, not on a fixed national cycle — this is a snapshot, not a live feed. Always check the relevant authority's current Air Quality Action Plan for a live scheme.

National Cycle Network

ncn.json — the National Cycle Network (Public): over 12,000 miles of signed walking, wheeling and cycling routes across the UK, with route number, surface, lighting and traffic-free/on-road status per segment. It is the "National Cycle Network" layer.

Contains Ordnance Survey data © Crown copyright and database right.

Operational-region boundaries

boundary_area_*.json — the "NH Operational Regions" overlay: one polygon for each of National Highways' seven operational regions plus London (Area 5). The shapes were reconciled against National Highways' own published regional maps (in the project's NH regions folder) and corrected using authoritative administrative boundaries.

Emergency Areas (ERAs)

eras.json — Emergency Areas (also called Emergency Refuge Areas / SOS areas): the marked refuge points on smart motorways where a hard shoulder isn't continuously available. It is the "Emergency Areas (ERAs)" layer.

The file structure (ArcGIS-style objectid/globalid fields) matches National Highways' other open-data exports, but the specific NH open-data catalogue item for this layer hasn't been individually re-confirmed for this listing — treat the exact source item as unverified until checked.

A&E Hospitals & Police Force HQs

hospitals.json — 194 major trauma centres and Type 1 A&E departments in England, with name, address and type. police.json — the 43 territorial police force headquarters of England and Wales, with name, address and phone number. These are the "A&E Trauma Hospitals" and "Police Force HQs" layers.

These two layers are curated reference lists, not an open-data extract with a licence and refresh cycle like the layers above. Hospital designations and force contact details can change — verify against the source organisation before relying on either for operational use.

Laybys & Truck Stops (National Highways lorry parking survey)

laybys_nh.json and truckstops_nh.json — the Laybys (National Highways network) and Truck Stops & Services layers. They show laybys and lorry parks on the Strategic Road Network and independent, local-authority, motorway and trunk-road service area truck stops in England, with facilities, capacity and how full each was when surveyed. The data was derived from the DfT National Lorry Park Survey 2022, carried out by AECOM for National Highways, and was prepared for the Lorry Parking Demand Assessment (2023).

Capacity and utilisation are from a crowdsourced survey and a snapshot in time. National Highways advises users to exercise caution and personal judgement with this data. Check availability, opening hours and charges with the operator.

Title Deed Boundaries (HM Land Registry INSPIRE)

{OSGridRef}.json — HM Land Registry's INSPIRE Index Polygons: the registered extent of freehold and leasehold titles across England and Wales, tiled by 1 km Ordnance Survey National Grid square and fetched live as the map viewport moves (nothing is pre-split or stored region-by-region). Each parcel carries an INSPIRE ID, registration date and a link to look up the title on HM Land Registry. It is the "Title Deed Boundaries" layer, and is the source for the single-parcel DXF export.

Indicative general boundaries only, not survey-grade. Contains HM Land Registry data © Crown copyright and database right, OGL v3.0. The polygons show the general position of a registered title's boundary, not its exact legal line — always confirm against the title register and, where it matters, a proper boundary survey before relying on a boundary for design, construction or a land ownership plan.

Live Roadworks (DfT Street Manager)

The Department for Transport's Street Manager service is where highway authorities and works promoters in England plan, permit and record street and road works. Its open data is published as a live, push-only feed of events on three topics: Permits (submitted, granted, refused, revoked, work start / stop and similar), Activities (created, updated, cancelled — for example scaffolding, skips and hoardings) and Section 58 notices (restrictions on works after recent resurfacing, created, in force, cancelled, closed). These are the three Street Manager roadworks layers in the app.

CivilsRoute subscribes to the three feeds with its own small relay service. Each event is converted to a map position (the feed uses British National Grid coordinates), stored as the latest state of that set of works, and served to the map for the area you are viewing. Works that have finished stay on the map, faded, for around 60 days after their end date and are then removed; cancelled activities are hidden.

This is a live notification feed, not an archive: events are delivered once and cannot be replayed, so any period when CivilsRoute’s relay was unavailable or over its service limits is permanently missing from the map, and works planned before collection began appear only once they next change. Positions are the centre of the works geometry reported by the promoter, not a survey of the works extent. Always confirm current works, permits and traffic management with the relevant highway authority or on Street Manager itself before relying on them for planning or on-site decisions.

National Highways live traffic feeds (DATEX II)

Four live layers come from National Highways’ developer-portal feeds, which are published in the DATEX II traffic-data standard: Digital Variable Message Signs (VMS) v1.0 (the “Live VMS Gantries” layer), Road and Lane Closures v2.0 (planned and unplanned), Road Limits and Features v1.0 (emergency telephones, emergency areas and bus stops) and Speed Managed Areas v1.0 (temporary speed restrictions). They are requested on demand through a CivilsRoute relay service that holds the subscription key, so the key is never exposed in the browser, and are shown as returned by National Highways — nothing is stored or archived.

Coverage is limited to National Highways’ own network, and the closures and speed-restriction feeds reflect only roads and lanes under active variable signs and signals. The feeds are rate-limited by National Highways (currently 10 calls per subscription key per minute, shared across these layers), so a layer may occasionally show slightly older data. Live data is indicative only — never use it as the sole basis for a safety-critical or traffic-management decision.

NH junction names, lane widths & speed limits

junctions_nh.json — the junction-number labels come from National Highways’ Network Model nodes. The junction names shown on roads such as the A30 and A38 are derived from the section names (TN field) in the Strategic Road Network Marker Posts dataset (see Marker Posts), which name the junction at each end of a section. Purely numeric names, bypass names and slip-road suffixes are dropped, so a small number of junctions still show no name.

lanes_nh.json — lane widths from the National Highways Network Model Lane table, joined to the Road Network layer by link ID.

speedlimits_nh.json — speed limits on National Highways roads from the RIS2 2022/23 speed-limit dataset.

Junction names are derived, not supplied by National Highways as a separate dataset, and may differ from signed names. Lane widths and speed limits are as recorded in the source data and can lag changes on the ground. Verify on site.

Traffic counts (DfT AADF)

aadf_points.json, aadf_hist/ — annual average daily flow (AADF) count points for motorways and A-roads, and each point’s year-by-year history shown in the AADT report. Built from the Department for Transport’s road traffic statistics bulk download, so the layer does not depend on a live API.

Counts are annual averages; some years at a point are estimated rather than counted (flagged in the report). Verify before using for design.

Network Flow (WebTRIS)

The Network Flow (WebTRIS) layer plots the permanent traffic monitoring sites on the Strategic Road Network (MIDAS and TMU sensors) from National Highways’ WebTRIS service, with annual average daily traffic figures for the selected site. Requests are relayed through a small CivilsRoute service so the browser can reach the API; the data itself is not altered.

Coverage is the National Highways network only. A site can be offline or missing days, which affects its averages. For roads off the network, use the DfT AADF layer. Verify before using a figure for design.

Ordnance Survey layers & place search

Four map layers and the address search come from Ordnance Survey’s free OpenData products through the OS Data Hub: OS Open Roads (the GB road network, all classes), OS Open Rivers, OS Open Greenspace, the OS Streets map (the Zoomstack vector basemap) and OS Open Names for place and road-number search. Layers are fetched live for the area you are viewing.

OpenData products are generalised and are not survey-grade. Verify positions and names against the originating source before relying on them.

Company-Owned Land (HM Land Registry)

The Company-Owned Land layer shows land and property owned by companies in England and Wales, one point per registered title. It is built from HM Land Registry’s Commercial and Overseas Companies Ownership Data: CCOD (UK-incorporated companies) and OCOD (overseas companies). The September 2026 editions were used. The data has no coordinates, so CivilsRoute places each title at the centre of its postcode using the ONS Postcode Directory, then publishes the result as pre-built map tiles that load as you zoom in. Each popup shows the owner, company number, tenure and address as recorded, with a link to the company’s page on the Companies House public register, which is a separate service run by Companies House and is not part of this dataset.

Indicative only. A point marks the postcode, not the property, so it can be some distance from the land itself. Registered ownership changes constantly and this layer is a periodic snapshot; confirm ownership against the title register before relying on it.

Base maps & routing

The background maps and routing are third-party services fetched live, each under its own terms:

• Standard street map — © OpenStreetMap contributors, under the ODbL.
• Satellite imagery and the topographic alternative — Esri World Imagery and World Topo Map, subject to Esri’s terms; attribution © Esri and its data providers.
• Terrain — © OpenTopoMap (CC BY-SA), built on OpenStreetMap data.
• Snap-to-road routing — the public OSRM demo server, which uses OpenStreetMap road data. It has no uptime guarantee, so a route can fail temporarily.

Routing distances are for chainage-style estimates, not for engineering design, and the base maps are not a survey record.

OpenStreetMap layers

The OSM speed limits layer is read live from OpenStreetMap through the Overpass API, via a small CivilsRoute relay that caches answers briefly. It is community-mapped, so it is indicative only and may be incomplete or out of date.

Mapillary street photos, signs & street furniture

The Street Photos layer shows where Mapillary contributors have captured street-level photos, and opens a photo when you click a point. The Signs & Street Furniture layer shows objects Mapillary’s software has detected in those photos (speed-limit and other signs, traffic signals, street lights, CCTV, poles and so on). Detections are automatic, can be wrong or out of date, and permanent safety barriers are not part of this dataset. Data is requested live through a CivilsRoute relay.

Check any sign, limit or asset on site before relying on it.

Processing & regional splits

The National Highways datasets are published as single England-wide layers with no region field. CivilsRoute splits them into the seven operational regions so the app can load one region at a time. That split — and the region overlay itself — has been corrected in stages:

• England clip — the overlay polygons' generalisation crossed the England–Wales border; clipped back to the ONS England land border.
• Severn crossings — South West extended ~450 m west to cover NH's own M4 Gwent Viaduct / Gantry G8W structures and the M4 / M48 geometry that legitimately sits in Monmouthshire.
• Three boundary fixes, verified against the NH maps: east Dorset (Bournemouth / Poole / Christchurch + the A31 / A35 / A338) moved from South East to South West; Glossop / High Peak moved from North East to North West; Rugby / M6 J1 / the M45 spur moved from East Midlands to West Midlands.
• Re-split — the Road Network, Red Line Boundary and Marker Posts were re-assigned to regions against the corrected polygons, so all the datasets carve the country up the same way (marker posts by their NH maintenance-area code; network and Red Line by geometry, each feature stamped with an nh_region property).

None of this alters the source data values — only which regional file each feature lives in and, for the region polygons, their extent. The transformation scripts live in the project's tools/ folder.

Licensing & attribution

Every dataset above is published under the Open Government Licence v3.0, which permits copying, adapting and commercial use with attribution, with these exceptions: the National Highways live DATEX II feeds, which are supplied under the National Highways developer-portal terms and conditions (see above); the HM Land Registry Company-Owned Land data, which is supplied under HM Land Registry’s own licence rather than the OGL (see Company-Owned Land); the base maps and routing, which are under the licences of their providers (see above); the OpenStreetMap layers, which are under the ODbL (see above); the Mapillary layers, under CC BY-SA 4.0 (see above); and the compiled A&E and police lists. CivilsRoute's attribution:

Contains public sector information licensed under the Open Government Licence v3.0. Data sources: National Highways; Department for Transport (STATS19; Street Manager roadworks); Environment Agency; Natural England; Historic England; Office for National Statistics; Sustrans (Walk Wheel Cycle Trust); DfT National Lorry Park Survey 2022 (AECOM); HM Land Registry (INSPIRE Index Polygons; Commercial and Overseas Companies Ownership Data); Ordnance Survey. Base maps © OpenStreetMap contributors, Esri and OpenTopoMap. Contains OS data © Crown copyright and database right 2026 (Ordnance Survey Licence AC0000827444, for the Red Line Boundary and Diversion Routes). Contains HM Land Registry data © Crown copyright and database right 2026.

A&E Hospital and Police Force HQ locations are compiled reference lists, not licensed open data — see the note above.

CivilsRoute is a visualisation and planning aid. Every figure, boundary and asset position must be verified against the originating source and confirmed on site before it is relied on for design or construction.