[03/06/2012]-Dart Services Resume Between Bray-Dun Laoghaire

[Jamie2k9]

Due to flooding on the line a Commuter train shuttle was operateing between Dun Laoghaire-Bary as a replacment for the Dart.

[karlr42]

Unusual forethought there, I can't remember that happening in previous flooding.

I presume the reason DARTs can't go through flooding is because the circuit from the OHLE through the train earths through the running rails, so if operating under water the water would be electrified?

[Kilocharlie]

Originally Posted by karlr42

Unusual forethought there, I can't remember that happening in previous flooding.

I presume the reason DARTs can't go through flooding is because the circuit from the OHLE through the train earths through the running rails, so if operating under water the water would be electrified?

More of an issue with keeping the traction motors in the bogies out of the water. The rails are not electrified but are earthed.

[Mark Gleeson]

Ground clearence on the Dart fleet is very low so does present a problem in flooding conditions

Once the water is below rail height it should be okay

Secondary issue is the ATP system might not work underwater, the ATP cannot be disabled on a Dart but it can on the diesel fleet

[Inniskeen]

Originally Posted by Mark Gleeson

Ground clearence on the Dart fleet is very low so does present a problem in flooding conditions

Once the water is below rail height it should be okay

Secondary issue is the ATP system might not work underwater, the ATP cannot be disabled on a Dart but it can on the diesel fleet

Unless things have changed, the DART ATP can, in fact, be partially disabled by the driver, but this only allows the train to travel at 30 kph. Were this not the case a DART suffering an ATP failure would only be able to proceed at walking pace and would effectively shut down the service. Normal procedure would be to de-train the passengers and continue empty to clear the line.

Interesting that a diesel shuttle was announced - did this actually happen ?

Given the deficiencies of the layout at Dun Laoghaire, the shuttle trains would either have to have operated on one line between Dun Laoghaire and Dalkey or else shunt via the connections at the north end of Dun Laoghaire station.

[Mark Gleeson]

Once disabled the ATP locks you to I think 20kph, can only be reset at the depot and has other implications (it triggers an alarm at the control centre) so not much use once you clear the effected region. I presume the DART safety case requires the ATP to be ON at all times save for an emergency move to the next station.

Routing would be south bound through station then reverse thus always uses the correct platforms

[Inniskeen]

Originally Posted by Mark Gleeson

Once disabled the ATP locks you to I think 20kph, can only be reset at the depot and has other implications (it triggers an alarm at the control centre) so not much use once you clear the effected region. I presume the DART safety case requires the ATP to be ON at all times save for an emergency move to the next station.

Routing would be south bound through station then reverse thus always uses the correct platforms

Fairly sure its 30kph. Presumeably the alarm to the control centre would reset if the ATP were re-enabled although regulations would probably require a seal to be re-applied

Not sure what you mean by the second point. You can only cross from one line to the other at the north end of Dun Laoghaire station. Any northbound shuttle service (from the Bray direction) using the northbound line and terminating at Dun Laoghaire must therefore shunt via the north end of Dun Laoghaire station in order to return on the southbound line.

The other option for a shuttle service between Dun Laoghaire and Bray would be to operate in both directions on the same line between Dun Laoghaire and Dalkey - an arrangement which might suit a situation where one line was more affected by flooding than the other.

Am I missing something ?