supporttheunderdog wrote:So Lordo, you have a length of track say 50 miles long. You have express that only calls at the first and last station and averages 100 mph. Slow trains call at more stations and average 50 mph. For safety you have to allow five minutes headway between trains.
The express leaves on the hour.. it will take 30 minutes to make the trip.
The slow train leaves at 5 minutes past the hour. It takes an hour to do the trip.
The next train is an express. What is the earliest time an express can then depart without being held up by the slow train?
That will show you the real problem that arises when trains with markedly different speeds use the same track...
If all the trains ran at the same average speed, whether express or slow train, one could in theory run 12 trains an hour, but with mixed use one is down to a lot less...simply putting in one train markedly slower and one then has to allow the difference in time to do the journey plus headway after such a slow train before a fast train can depart. It is why Virgin is limited in how many trains it can run, as eg it has to share track with NW trains,....
Build a new line and then Segregate the fast and slow trains on dedicated lines and you are up to a theoretical 24 trains an hour.
As to adding extra lines, Expanding the existing tracks is simply not practical...it is far more than just widening a few bridges,,, it is widening cuttings and embankments, adding tunnels, it is wholesale demolition of thousands of trackside buildings, plus disruption on the existing lines. That is why expanding existing lines has by and large been dismissed.
I would venture to suggest it is in fact you who do not understand rail construction...
And btw if you look at the Virgin Website you can see the train and carriage layouts, and first class is nowhere near 50 percent of seats.
Answer..
The first express arrives at +30 minutes.
The slow train arrives at +65 minutes
The next express cannot arrive until +70 minutes (or later) so can leave at +40 minutes (at the earliest).
The next slow train can leave at +45, at the earliest, meaning intermediate stations see two trains in an hour stopping at best every 45 minutes, not twelve trains an hour.
you can read all the crap you like. when you see they are building a 250 miles an hour train line, you can clearly see that the intention is not to build it but defraud the tax payer. and they have done that very well. over 7 billion spent and not a single track laid. says it all.
there is plenty capacity on the line and there is a lot of ways to improve transport especially off the road for goods transport.
british rail was brilliant at designing the railways and has plenty of places they can hold a slow trains without affecting the express trains. there are express and slow trains on every single line.
with a bit of luck corbyn will bring them back free of charge as they will not renew their licences.