Usage

Safety

The railway and geographic information contained within this web site is indicative in nature and should not be treated as definitive, complete, or authoritative. It must not be used in any way that could adversely affect the safety of railway personnel, passengers, members of the public, or the environment. This site is not a substitute for official Network Rail publications and must not be used for any production or safety-critical task within the railway domain.

Background

Geofurlong provides indicative notional mileage and kilometre positions on Network Rail owned or maintained lines, referenced by Engineer’s Line Reference (ELR). ELRs are the alphanumeric identifiers used throughout the GB railway industry to define discrete sections of track, and form the backbone of mileage-based asset referencing on the network.

The Geofurlong geospatial model is derived from Network Rail’s published track centre-line and milepost datasets, combined with extensive computational analysis and manual validation. The result is a practical reference for engineers, planners, and third parties who need to locate, cross-reference, or visualise linear positions on the network.

Scope

All Network Rail owned or maintained lines are included, regardless of current operating status — this covers active main lines, freight-only branches, and closed or mothballed alignments. Routes formerly managed by British Rail but now outside Network Rail control are also included where data permits. The Core Valley Lines (CVL), transferred from Network Rail to Transport for Wales (TfW) in 2020, are included within scope.

Accuracy

The tabular data and map markers provide indicative geographic positions and may not precisely reflect true mileage positions in every instance. Inaccuracies can arise from a range of factors, including:

Route changes — a realigned or rationalised section alters the physical distance between original mileposts, creating a discrepancy between the recorded mileage and the current geography.
Milepost repositioning — mileposts may have been moved during engineering works, or deliberately positioned at the end of a structure where a conventional location was impractical.
Source data anomalies — the originating Network Rail datasets do not guarantee complete accuracy, as noted in their own open data releases.

For any given mileage, the indicative geographic position is computed with reference to the measured linear distance between the adjoining mileposts. The resulting positional accuracy (for example, ±6 metres along the railway) reflects the variance between the reported and measured milepost spacing for that section.

Data validation is incorporated throughout the Geofurlong build process and is presented in the following ways:

Summary page — the reported length of each ELR (derived from start and finish mileage values) is compared against the measured geographic length. Where a noticeable discrepancy exists, it is shown on the ELR summary page. Known anomalies are recorded in the Remarks field.
Correlation — an automated validation suite cross-references Geofurlong-computed positions against independently produced Network Rail datasets. This combined dataset currently exceeds 365,000 infrastructure items with ELR, mileage, and geographic position. The results confirm strong correlation with Network Rail-computed positions.

In addition to automated validation, significant effort has been invested in manual review of computed positions, using satellite imagery, historical records, and site-specific knowledge across a wide range of identifiable infrastructure features.

Attributions

Railway ELR centre-line, track centre-line, milepost, and organisational geospatial data: Copyright © Network Rail, released under the Open Government Licence 🔗. Network Rail make no claim that these datasets are entirely accurate or complete.
Network Rail data utilises Ordnance Survey data: Crown copyright and database rights 2025 Ordnance Survey AC0000849662.
Place names and administrative area geospatial data: Copyright © Ordnance Survey, released under the Open Government Licence 🔗.
Junction locations and names based on a combination of local knowledge, OpenStreetMap data, Network Rail Sectional Appendices to the Working Timetables, and National Libraries of Scotland maps.
Tunnel, viaduct, and station details based on a combination of location knowledge and data released by Network Rail under the Open Government Licence, Copyright © Network Rail.
Line of Route data derived from a combination of Network Rail Sectional Appendices to the Working Timetables, Network Rail Engineering Access Statements, TRACKmaps 🔗 hard-copy books, and Railway Codes 🔗. TRACKmaps and Railway Codes draw on contributions from numerous railway personnel, all of whom are gratefully acknowledged.

Licence

All outputs from this web site are released under a CC BY 4.0 Creative Commons Licence. You are free to distribute, adapt, and build upon the material — including for commercial purposes — provided attribution is given, for example: “Data provided by geofurlong.com”.

Privacy

Geofurlong does not use cookies or collect any information that could identify or track individual users. Infrastructure providers serving the web pages and background map tiles record aggregate usage for billing and service optimisation purposes only; no personal data is collected.

Disclaimer

THE CONTENTS OF THIS WEB SITE ARE PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT. IN NO EVENT SHALL THE AUTHORS, DEVELOPERS, CONTRIBUTORS, OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES, OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE WEB SITE CONTENT OR THE USE OR OTHER DEALINGS IN THE WEB SITE CONTENT.