We have been involved with many electrification projects around the UK, including the Paisley Corridor Improvements, Edinburgh Glasgow Improvement Programme, North West Electrification Programme and currently the Great Western Electrification Programme.
On the Glasgow Paisley Corridor electrification project we worked with the Network Rail Team who are now involved with the current RaCe (Rutherglen and Coatbridge Electrification). Despite the avid use of 3D models on the Paisley project to avert clashes and sighting issues, the project has experienced many problems, which can be related to:
- Incorrect or out of date CAD design data.
- Temporary works/stages not being modelled due to budget constraints.
- Installers working to different datum and methods of setting out.
- Detailed designs not being updated into the 3D models until it is too late.
The result of this gave rise to instances of signals being obscured, trains at low speeds and project teams with sleepless nights.
In the end, the issues were resolved but all involved agreed that they were avoidable had they just been fully committed to using the available technology. To avoid repeating the same problems when RaCe appeared on the project the NR team took the following steps:
- Ensuring that all disciplines are working to the same datum/chainage.
- 3D/BIM(building information modelling) processes will be employed early to ensure that clashes are removed.
- GPS technology will be used instead of wheels for setting out.
A simplified overview of the project’s scope was to electrify the existing railway between Whifflet and Carmyle without affecting the existing signalling. It also ensured that the proposed Motherwell resignalling, due to be installed in two to three years’ time, was unaffected. The general design principles were adopted to:
- Consider TTC structures on curved approaches to signals.
- Employ HD video and 3D BIM as part of the IDC (inter-disciplinarily check) process to prove that sighting is unaffected.
- Do everything possible to ensure that all disciplines are coordinated.
- Stop using surveyor’s wheels.
Stage 1 – Existing signals
- Once the early Grip 4 design was underway, we set out with the assistance of First ScotRail to film the existing railway using GPS for coordination. A topographic survey was conducted, which was run though the snake Grid process by engineering company, URS. Hyder based the OLE design model on the topographic survey, which included a project-wide meterage. This was provided to us to correlate the video model against it. The raw video model (existing view) was provided to aid the design and IDC, we ran through a coordination process to ensure that as-built positions and offsets of the designed OLE (overhead line equipment) piles were incorporated in the model. Once the initial models were available, an IDC workshop was help to identify any issuses, if issues were found they were designed out. The project has a robust design and has no sighting issues.
Stage 2 – Proposed signals
Use the schemeplane and SSF’s (Signal Sighting Forms) from the SDG (Signalling Design Group) to plot the proposed signals in the model to prove sighting.
Signalling longitudinal references did not appear to match the project meterage being used so Hyder used schemeplane data to plot new signals on the OLE CAD model. We then ran a separate correlation to plot the locations using SSF’s and cross-checked it with the schemeplan and Hyder model.
In some cases, three to four different locations could be determined for a signal, depending on weather the following was used:
- Schemeplan meterage
- SSF Chainage
- SSF reference location
- Measuring along the up, as opposed to the down, lines
Following an IDC meeting, Gioconda proposed that the simplest method was for a survey team, aided by SDG to put out a physical marker for the proposed signals the to be GS surveyed and logged. These positions were placed on the CAD model and then on the 3D Model used for sighting assessment.
SSF’s and Shemeplan were updated accordingly and any signals with sighting issues could be moved with reference to the surveyed location.
As a project and team we set out to use this technology to remove the problems that have been encountered on many other past schemes and it has worked extremely well. While it is true that the project had a few issues, they were resolved swiftly by continual use of the 3D BIM and video technology. In all, for a project with more that 500 structures dealing with existing and new signals, all involved were “please with the results”.