Short answer: an Engineering Scale Plan (ESP) is a drawing of a railway station yard or section, made to scale, that shows the tracks, points and crossings, platforms, buildings, bridges, level crossings and other features in their true positions with chainages. Railways use the approved ESP as the base for planning works such as yard remodelling, new lines and signalling plans.
What an ESP shows
- All running lines, loops and sidings, with track centres
- Points and crossings (turnouts), with their positions
- Platforms, foot over bridges, station buildings and goods sheds
- Bridges, culverts, level crossings and road over or under bridges
- Railway land boundary and nearby features that affect the work
- Chainages (kilometrage) along the line
When an ESP is needed
An up-to-date ESP is usually needed whenever the layout of a yard or section is going to change: yard remodelling, new lines, doubling or tripling, new platforms, goods terminals and sidings. Other drawings, such as signal interlocking plans, are typically prepared from the approved ESP, so errors in the ESP flow into everything that follows.
How an ESP used to be prepared
Traditionally, survey teams measured the yard on foot with total stations and tapes. In busy yards this means long hours working next to live tracks, with the work squeezed into traffic blocks, and it is easy to miss details that are only noticed later.
How drones and LiDAR change it
- Plan: fix the extent of the yard, the coordinate system, permissions and flight timings with the railway.
- Ground control: surveyors place and measure GCPs with DGPS at safe locations around the yard.
- Capture: the drone flies the yard in a short window, capturing photos and, where needed, LiDAR.
- Process: the team produces an orthomosaic and terrain model accurate to a few centimetres, checked against independent checkpoints.
- Draft: drafters trace every track, turnout and structure from the georeferenced base in CAD.
- Verify: the field team checks critical details such as turnout positions and chainages on the ground.
- Deliver: the ESP in CAD (DWG) and PDF, with the orthomosaic as a reference layer.
Why it is worth it
- Safety: far less time for staff on or near live tracks.
- Completeness: the orthomosaic records the whole yard, so missed details can be checked without another site visit.
- Reuse: the same survey supports drainage plans, land plans and progress monitoring later.
Learn more about our ESP and DPR surveys and railway survey work.