22-06-2010, 09:52 PM
(20-06-2010, 03:03 PM)alexgoei Wrote: 2 Your point about saving some time when the train is accelerating to reach full line speed - So would it correct to say that to determine if 3 aspect signalling could meet the stopping requirement headway of 218 secs (with 10% contingency) it would be necessary for completeness to incorporate a further 15 secs which is the time taken in order to reach the full line speed of 100 km/h? If the answer is yes, for this particular layout and with 10% contingency, the headway time between 2 trains both travelling at 100 km/h would be 226 secs. And therefore the conclusion that 3 aspect signalling would not have been able to meet the stopping headway requirements.
Yes and no. As I said in the earlier post, the extra distance that you have to travel to complete the acceleration, you must take off of the distance (and hence time) that you travel at line speed. So while you have to add on 15 seconds for the acceleration, you take off 13 seconds for the 364m that are now not being travelled at linespeed.
In this case it does not make a lot of differnece to the outcome - a change of 2 secs, so your assertion that 3 aspect works was correct and it may seem pedantic, but getting to the right answer for the wrong reason will do you no favours if it could lead to other errors in the future.
I hope I have managed to explain that OK.
Peter