2011 Q3 Risk associated with passenger trains in tunnels

[PJW]

Attached is a file containing an attempt by a participant at the recent Mod1/Mod7 Exam Workshop who attempted this question.

[reuben]

Hi

I'd like to add some more to the mix:

Risks

Difficulty of evacuating a failed train (tripping and falling) / secondary risk of detrained passengers being exposed to traffic on neighbouring line.

Occurrence of rockfall / tescofall (well, it has happened, and it logically follows the same verbal construction as "rockfall")

Inability of driver to inspect line / "proceed as far as the line is clear" as per rule book.

Trains striking other trains / tunnel wall due to reduced clearances.

exposure of maintenance staff to a more hazardous work environment

Greater difficulty in performing track inspections, hence increased risk of derailment/ structural infringement due to unidentified track fault.

Wet conditions in tunnels tend to accelerate corrosion , hence aggravates previous item.

wet conditions in tunnels tend to make track circuit failures more likely, hence increases secondary risks associated with degraded operations.

On a busy metro railway, passengers confined for a period in a tunnel between stations can suffer stress/ heat related injuries. The mitigation is always to try to acheive station-to-station running, even though the stations are themselves in the tunnel.

Tunnels are well thermally insulated, and all traction energy and human heat output has nowhere to go, hence tunnels will inevitably exhibit a long-term upward temperature rise - aggravating the previous issue.

There's a long tunnel in Canada where, I think i recall, the prevailing wind results in a steady breeze in one direction. A diesel locomotive pulling a slow heavy train in this direction never escapes from its own exhaust cloud, resulting in engine overheating, besides the obvious carbon monoxide poisoning. The mitigation is a forced ventilation system, which itself requires a "draught door" to close across the tunnel behind each train. It's only made of thin plywood, in case it gets hit!.

Reuben

[dorothy.pipet]

an attempt for comments please