Running more trains

The number of trains that can be run down a track in a given period depends on a number of factors:

1. Speed

2. Signalling

3. Stopping pattern

4. Terminus platforms and dwell-time

5. Junctions

The maximum speed a train can travel at is determined by the distance it needs to stop at a red light.  Clearly trains cannot hurtle around at 100 mph if the stopping distance provided by the signalling requires trains to travel at no more than 60mph.  What you can do is change the signalling to permit 100mph running.  The number of trains that can be run depends on the time that has to elapse between a train passing a signal and how long it takes to travel down the track before the signal it passed is able to permit the following train to pass at the same speed.

The number of trains that can be sent down the line is limited by the number of stops trains make.  Thus between Tonbridge and Sevenoaks the number of available 'paths' is reduced by some trains stopping at Hildenborough and between Sevenoaks and Orpington  by trains stopping a Dunton Green, Knockholt and Chelsfield.  Close these stations and capacity would be increased.

Another major constraint is the number of platforms at a terminus and how long it takes between a train arriving and departing.  It is no good sending 20  trains an hour towards a terminus if they have to stand outside a terminus which can handle only 6 trains an hour.

Junctions reduce capacity considerably, particularly if they are 'flat' junctions with conflicting train movements.

The problem in the south-east is that some routes are almost at full capacity:  the London to Brighton route via Gatwick  and the route between Tonbridge and Orpington being the worst.   The problem on both routes is that it only needs minor delays to a few trains or a breakdown to render the timetable a work of fiction. 

The rail industry has not come up with any solutions to alleviate the problem of under-capacity on these routes. It is a ticking bomb. 

Since writing this I have come across this interesting article:

http://www.bml2.co.uk/the-news/80-do-minimum-wont-do.html