Train Regulation

[Bald Rick]

Sorry, please can someone explain to me why the regulation policy even mentions PPM? A train failing PPM is bad, but only because this train is late, and surely this is already mentioned (as minimisation of delay, and efficient use of infrastructure)? Is this just a case of minimising delay penalties rather than actual delay?

Quite the opposite. Regulating for PPM can cost more in delay penalties. But PPM has been deemed by Government and the ORR as the most important measure of performance, therefore that is the target you aim for.

 

[Tomnick]

Thinking about it, if the PPM has gone down the pan I would be looking at the next booked working for the passenger set. If there was a decent turnaround I'd run the freight as I'd bet you nail it for 2-3 minutes just getting it in the loop, probably another 3-4 waiting for the passenger to pass and then another 3 trying to get the trucks back up to speed. The delay to the passenger probably wouldn't put it into CaSL.

It's an interesting illustration of the sort of thought process that goes into a good regulating decision! If the freight's R/T, I'd certainly give serious thought to keeping it going. I think that you'd knock it for q minimum of ten minutes, probably a bit more, if it went in...though it's worth checking the pathing allowance later in the schedule to see whether it'd recover from that. If the passenger's late, the next one might not be a million miles behind either, so it might be tight getting the freight out again - bearing in mind that they might not be able to deal with it straight away at the next regulating point if it's out of path.

Sorry, please can someone explain to me why the regulation policy even mentions PPM? A train failing PPM is bad, but only because this train is late, and surely this is already mentioned (as minimisation of delay, and efficient use of infrastructure)? Is this just a case of minimising delay penalties rather than actual delay?

As a passenger, I think PPM's a worthwhile thing to aim for - I'd rather everyone be working towards recovering the delay to a point at which planned connections into other trains might be achievable than thoroughly stuffing a late-running in order to keep another within some arbitrary target. Minimising the overall delay and regulating for PPM do fit well together to a certain extent anyway, but I think that it puts a bit more focus on individual trains.

 

[WestRiding]

oh Christ! wanabe signalmen!

 

[Tomnick]

Who is??

 

[IrishDave]

As a passenger, I think PPM's a worthwhile thing to aim for - I'd rather everyone be working towards recovering the delay to a point at which planned connections into other trains might be achievable than thoroughly stuffing a late-running in order to keep another within some arbitrary target. Minimising the overall delay and regulating for PPM do fit well together to a certain extent anyway, but I think that it puts a bit more focus on individual trains.

There's an inherent contradiction between the two bolded statements - PPM regulation usually consists exactly of stuffing a late-running train (more precisely, one that's "out of PPM") to the back of the queue.

For example, every other day at Coventry, when a northbound XC to Manchester is 11 minutes late, the stopper that's booked to follow it is allowed to go in front, and any passengers hoping to make the connection at New Street to the XC to Leeds and Edinburgh is stuck while they plod along behind the stopper. Sometimes the stopper will get held at Coventry, or even looped at International (in either case it will almost certainly fail PPM), but more likely the XC will stay behind because, provided it's let out of New Street in front of the stopper to Wolverhampton, it'll be no more than three minutes late into Manchester, because it's got so much pathing time.

Case in point: Tuesday's 0515 Southampton-Manchester - I've seen pretty much exactly that happen many, many times.

All that goes to show just how terrible PPM is at measuring performance.

 

[greatkingrat]

And what about people on the stopper who may have had connections of their own to make at New Street?

Had the stopper been held at Coventry until the XC service had gone through, it would have just ended up delaying the next Pendo instead.