(19-03-2009, 04:17 AM)alexgoei Wrote: Hello Peter,
Finally is there any need to work out if the Branch (which is single line operation) can support a stopping headway of 4 minutes?
Thank you and Regards
Answering for now just the quick and easy bit! DEFINITELY NOT.
It would of course be possible to signal the line to allow a "flight" of trains in one direction at 4 minute headway between each one of them for say 20 minutes, then when the last of them has cleared the section then timetable all the return trips at 4 minute intervals. This would be a way of maximising traffic that could be carried on a single line (and more applcable to heavy freight moves than passengers). This would presuppose some form of storage facility- I suppose there could be a large fan of sidings within the power station beyond the track depicted on the plan for example.
However look at the traffic requirement- 6 a day freight between C&B, 2 per hour stopping passenger between A&E; obviously 4 minute stopping headway is not required.
What you should do though is determine how youe would be able to fit on the single line section 4 passenger trains per hour and have enough spare capacity within that hour's operation to get at least one freight path (i.e. during one hour schedule a train from D to B and in the next hour the return working from B to D). Therefore some form of consideration of how long it would take passenger train leaving D to clear the points at 1040 (NB plan typo!) to permit a train from A to be signalled and then travel sufficiently to clear points at 2780 to then allow a freight being held on the Up branch to then travel to clear junction B thus freeing up the line for the next passenger train DOES need to be undertaken. You don't necessarily need an accurate figure to give the maximum line capacity; do just enough to show that it could be made to work. Such a consideration should then influence your decision of how to signal the branch in the area of junction B; for example it could mean that operating the points here from a Ground Frame might not be sensible as it would just add too much delay for the operation to be feasible........
PJW