It started with a question that was posed to me, in a roundabout way, by a passenger of First Great Western. In a nutshell, they wanted more Heathrow Connect services, both into and out of Paddington, to stop at Acton Mainline, a tiny station right next to Paddington. Their rationale for this was 'All you have to do is make the train stop, because there's enough time built into the timetable for it.'
At this point I sigh, because if only it were that simple. Here's the technical bit.
The UK rail network, especially the lines between Reading and Paddington is very finely balanced. You alter one thing, and it affects others. This what some people just don't seem to be able to grasp.
The problem lies in that the turnaround time for trains at Paddington is a maximum of 9 minutes. Extra stops in either direction erode turnaround times and make the consequences of delays a lot more costly. With me so far? Good.
Further away from Paddington, there is a crossing pint where trains can switch lines called Heathrow Tunnel Junction. It's a piece of single-line track, only one train at a time goes through. The pattern is set so that 'down' trains (those leaving Paddington) cross the junction and then 'up' trains cross 2 minutes later. The times for each train at this junction are fixed.
A stop at Acton Mainline for the 'down' train would mean that it would have to leave Paddington earlier so that it would still make its slot at the junction. No problem so far, right? Except that it can't do that because there is a service to Oxford that leaves Paddington 3 minutes earlier that would occupy that slot. The depature time of that service to Oxford is fixed as well because it is dictated by the time that the stock for that train arrives from Oxford.
The point being that if the Heathrow Service is changed, then the Oxford service has to be changed, which means that the service before that has to be changed and any services that connect to and from it have to be changed so that they still connect, and so on.
It's not as simple as you might think. In fact, it's bloody complicated. That was a slimmed and simplified version of what's going on. One day, I may post the full version just for comparison. And that is just one stop in one small area.
Forgive me if I sound rude, but there are several lesons to be learned from this.
1) Just because you travel by train, does not mean you know how to run a rail network.
2) Just because a change would make your life more convenient, does not mean it's a good idea, or even possible.
3) If a train company tells you that something is not possible, instead of arguing the toss for 8 letters like that guy did, every once in a while, no matter what you think of us, accept that sometimes we do know what we're talking about.