Quote:
Originally Posted by Mark Gleeson
There is a massive performance difference. There was a Sunday morning Dun Laoghaire Drogheda train which called all stops. It routinely was 5 minutes down against published time by Pearse which was longer than a DART time
The old times were based on a railway were absolute priority was granted at all level crossings, no delays due congestion plus there was a tendency to be a bit generous with the rules and speed limits. Trains ploughing through Merrion Gates was a routine event.
We have submitted to the NTA 2030 vision that the level of priority granted to DART and Luas services be increased significantly at crossings. This would take minutes to implement and save hours literally on a daily basis. The DART is assigned level 6, the lowest level.
Each stop costs minimum 75 seconds, 150 seconds, add 2 minutes for the level crossings and further minute for the ATP. The net time would be 35 minutes vs 45 minutes
The northside is a different animal as the line speed is 70mph, DART is limited to 60mph and the gaps between stations are significantly longer than on the southside. I'd still bet money on a DART in rush hour conditions winning an all stops race. Do the numbers on running costs and the DART wins by a large margin. There was an assessment in the DART business case which compares diesel vs electric times which shows a significant time saving.
|
No question, in theory an electric service should deliver a massive performance boost when compared with a diesel operation, especially for a service making frequent stops. DART does not generally deliver anything close to the expected bonus due primarily to the very crude nature of the control system, lazy scheduling and ridiculously extended station times. Also the nature of the ATP means that one DART closely following another unnecessarily looses significant amounts of time crawling into stations against a danger signal located beyond the end of the platform. For this reason alone, the frequecies being quoted for the city centre re-signalling (20 trains per direction per hour) is fantasy land stuff.
DART performance (due to the ATP) is de-facto inferior to diesel performance between Bray and Greystones (by several minutes), entering Bray southbound, entering either platform at Malahide (by about 1 minute), between Howth and Howth Junction (1½ to 2 minutes) and through the south side level crossings.
By any measure current DART performance is poor with journey times about 25% longer now than when the service was initially introduced. Bray/Connolly, for instance, originally took 36 minutes and now takes 44 minutes -the only differnce being an additional stop at Grand Canal Dock. While the length of DART trains has increased, cameras are provided to assist drivers in operating the doors and buzzers have been provided to alert passengers to stand clear. In general DART loadings are not especially heavy and it is rare to experience delays entering and exiting the trains due to onboard congestion - hence this is not a valid factor in diminished performane.
DART never had priority at the level crossings largely because signal spacing is set up for mainline trains operating at line speed, something which nowadays almost never happens due to the way in which timetables are designed. Trains to and from Rosslare crawl throgh the level crossngs even on the rare occasions when there is not a DART immediately ahead.