Overhead Line Equipment
How problems with overhead lines cause delays - and what the industry is doing to reduce them
Overhead line equipment (OLE) refers to the cables and supporting infrastructure that carries electricity at 25,000 volts to power trains.
Problems generally fall into two categories:
- Power supply failures - electric trains cannot run but diesel trains can still use the track
- Mechanical problems, for example the wire is down or parts are displaced from the gantry - no trains can run until the broken equipment is cleared away, then diesels can run and, if the affected part is short enough, electric trains can coast past
When the failure is serious, for example if the wires have been brought down by a falling tree or are tangled in a train’s pantograph (which allows it to draw power from the overhead lines), the solution is more complicated and takes more time. Where this happens, passengers may need to be evacuated off the train.
What the industry is doing to reduce faults and delays
- Measurement Trains run computerised checks on the OLE during inspections, providing information to fix potential problems before they affect services
- Routinely inspect the OLE manually from both ground and high level
- Investment to upgrade OLE is coordinated nationally to target the routes that are most at risk of problems and those with the highest traffic
- If it is possible to do so, run diesel trains or coast electric trains through the area and repair the OLE overnight, reducing disruption to trains
- In straightforward cases trains can be back running again quickly, though temporary speed restrictions may need to be imposed until the problem is fixed