Signaling Headways & passing loops - particularly South Wales Main Line

[Rhydgaled]

I'm frequently messing around with Excell spreadsheet timetables for various parts of Wales (particularly the south, but also other parts), largely just out of interest to see if certain enhanced frequencies would be possible given infinite rolling stock. However, to be sure what I come up with would really work I'd need more information on the headways available.

One major example is the South Wales Main Line portion of the GWML. I found something here which says "On the basis of 4-6 minute headways we can identify at least 6 fast (20 minute) and 4 slow (30 minute) all stations or freight paths between Bridgend and Cardiff." The scenario I've made up from that is four fast passenger trains per hour (calling at Bridgend and Port Talbot) between Cardiff and Bridgend and two all-stations, with the remaining four paths (2 fast 2 slow) reserved for frieght. Of the passenger services, 3 fasts (one each from London, Bristol and Manchester) would continue to Swansea (calling at Neath also) and one to Carmarthen/Fishguard/Milford Haven via the Swansea District Line. One slow would be the Maesteg service, the other an hourly Cardiff - Swansea all stations 'Swanline' service.

The thing is, the Swanline takes 1hr 13min and the faster Swansea services 54min. This means I don't seem to be able to timetable the fasts without them overtaking the stoppers somewhere. Assuming the link above is correct in saying there are 10 paths per hour, where are the passing loops to permit that (I know I've seen a loop in the middle of nowhere while traveling on the line, but can't say exactly where)? Certainly, I've never noticed a loop at a station for stoppers to wait in to be overtaken. That link also only covers Cardiff - Bridgend, so maybe the headways further west are less capable.

Thanks in advance for any information on the capability of the rail infrastructure in this, and other parts of Wales, you can provide me with.

 

[MggW]

It's four stopping pass OR freight paths. You can't run a freight in the fast pass timings.

In answer to you question, the answer will be to flit the fast trains together, then run all the slower ones to maximise use of the capacity.

 

[The Planner]

Do a search for the timetable planning rules on Google, it is all in there. GW900 runs on a 4 minute headway until Swansea im sure.

 

[Tomnick]

The thing is, the Swanline takes 1hr 13min and the faster Swansea services 54min. This means I don't seem to be able to timetable the fasts without them overtaking the stoppers somewhere. Assuming the link above is correct in saying there are 10 paths per hour, where are the passing loops to permit that (I know I've seen a loop in the middle of nowhere while traveling on the line, but can't say exactly where)? Certainly, I've never noticed a loop at a station for stoppers to wait in to be overtaken. That link also only covers Cardiff - Bridgend, so maybe the headways further west are less capable.

Quail doesn't seem to show much in the way of passenger loops (one on the Down just east of Bridgend and a short section of Up Relief through Port Talbot - but avoiding the platform there!) - the rest are all goods loops. Not sure if any resignalling has changed anything though. Based on your timings above though, a flight of three fasts (the first departing at xx:00, the third at xx:08) followed by a slow at xx:12 (arriving x1:25) would only knock the following fast (xx:30 departure) by five minutes.

 

[Rhydgaled]

It's four stopping pass OR freight paths. You can't run a freight in the fast pass timings.

I wouldn't expect diesel frieght to manage to use a fast passenger path, but if a 75mph class 150 (albeit not even stopping at the major stations) can do it then (if, as I hope, the GWML is electrified all the way to Swansea) a 75/110mph class 90 or 87mph class 92 might be able to manage a frieght in the fast path (given that, as it is a frieght, it doesn't need to stop at any stations). Is there any reason why electric frieght couldn't use a fast passenger path?

Do a search for the timetable planning rules on Google, it is all in there. GW900 runs on a 4 minute headway until Swansea im sure.

Thanks, helps when you know what to search for. I haven't had a chance to have a good look yet, but it looks like that might be just what I was looking for.

 

[The Planner]

I hope so, as it is what we use !! As for the freight, if it fits, then it can have a path. A Class 4 train often works better than a stopping passenger service.

 

[Pacerpilot]

Ive been into the following loops with Passenger trains to allow faster services/ late HSTs to pass:

Tremains
Pencoed (was a booked waiting point for 2F52 until the Dec'11 timetable change)
Stormy

All of which come under PT's control and are approached under flashing yellows, which allow a faster approach as you arent bearing down on a red. Never been into Miskin.

And you could always use the OVE line at Margam.