Swansea District line

[Rhydgaled]

The proposal to build a line from Pontarddulais to Gowerton is pure fantasy - large tracts of the old route have been built over, and there was no junction to rebuild.

I've Googled-Earthed the route, and it looks to me that very little of the SDL-Gowerton route has actually been built over. The junction onto the current line at Gowerton looks like the difficult bit.

The report draws a comparison between the Valley Lines and the lines around Swansea - the Valley Lines run into Cardiff, while the District avoids it. There can't be an urban network in Swansea because the lines on which to run it just aren't there any more - they've all been built over.

I agree the SDL itself can't be compared to the ValleyLines. However the freight lines to Onllwyn and (nearly) Glyn-Neath look like they could be compared to the ValleyLines as, maybe, could Gwaun-Cae-Gurwen if the SDL to Gowerton link existed. The problem with the first two, as I mentioned in the video, is that the frieght line only gets to Swansea Docks and the service would probably need to be a tram to get into the city centre.

 

[Tomnick]

That is the arrival though and you factor the approach control into the loop in the first schedule, you then pass the second train at the headway value based on the arrival time of the first train. Ideally the first train is far enough infront to not have to add pathing time in the second train, thats why capacity can never be fully utilised.

Yes, sorry if I wasn't clear - I'm thinking of the overall dwell time in the loop for the first train.

The favoured (STP) option at the moment does seem to be to plan it such that the second train inevitably gets delayed because insufficient time's been allowed for the first to get inside, destroying the margin for the first train to come back out in the process .

 

[cmjcf]

I've Googled-Earthed the route, and it looks to me that very little of the SDL-Gowerton route has actually been built over.

I've Real-Earthed it. The junction at Pontarddulais has been built over - it's now the station car park. South of Water Street, there's a new access road for Tesco. Gorseinon station is now under a roundabout (for Asda), and there is then a housing estate and an industrial estate to the south. The approach to Gowerton has been built over, including the car park on the "new" road. The west end of Gowerton station abuts residential development, so no way to thread a junction through there.

However the freight lines to Onllwyn and (nearly) Glyn-Neath look like they could be compared to the ValleyLines as, maybe, could Gwaun-Cae-Gurwen if the SDL to Gowerton link existed.

Those are both well outside the city, in different counties even. IMV, the routes that could probably be closest to the urban railway in Cardiff would be the old Mumbles Tramway, the old route into Victoria that is now the Clyne Valley Cycle Path, the Swansea Vale route (via Morriston East), and the low-level route through Landore (via Morriston West). Of course, all of those are now gone. Other than the Swanline stations and possibly re-opening Cockett, the other options all point the wrong way. If a couple of bits of track were different, doubtless people would be calling for the N&B and/or the Vale of Neath to re-open with fast trains via the District.

 

[edwin_m]

As I understand it, if the headway was 4min the stopping train would need to be timed at least 5min ahead of the non-stopping train to allow for deceleration including any approach control, and also overlap timeout if the loop is short. Taking this figure the stopping train would wait about 4min before the non-stopping train passed through, and could depart on a single yellow a minute or so later. The total wait is about 5min so about 4min longer than a normal stop.

 

[gwr4090]

Bear in mind that the electric trains that are proposed are longer than the diesels that currently work west of Bridgend. 153s, Pacers, Sprinters, and some 3-car 175s, as against 4-car 315s. That's going to tilt the ORCATS shares on stations west of Cardiff significantly. A rough calculation suggests FGW run 16cph between Cardiff and Swansea (one HST each way), while for ATW this is perhaps 7cph. With the longer EMUs, this goes up to 12 on the current frequency, and with an hourly Swanline that could be 16. If it works the way I think it might work, the potential hit at Swansea from the Western operator not operating more services that way is at least twice as much as they might gain from operating through to Carmarthen instead. (Disclosure: It probably doesn't work the way I think it might work.)

I seem to recall that according to the draft DfT timetable that was used to fix the size of the IEP fleet for the GWML, quite a few of the 8-car Swansea-London HSTs are likely to be replaced by 5-car bi-mode IEPs so the total number of carriages may actually decrease. Only a proportion of the services will be worked by 9-Car electric IEPs, with one or two worked by 2x5car bimodes of which one unit will work to/from Carmarthen.

 

[cmjcf]

I suppose that with the faster journey times, there's your fast train for Carmarthen right there.

 

[The Planner]

As I understand it, if the headway was 4min the stopping train would need to be timed at least 5min ahead of the non-stopping train to allow for deceleration including any approach control, and also overlap timeout if the loop is short. Taking this figure the stopping train would wait about 4min before the non-stopping train passed through, and could depart on a single yellow a minute or so later. The total wait is about 5min so about 4min longer than a normal stop.

No, as the headway is based on the first train having arrived in the loop, you dont need to add anything on. The running time of the first train has the deceleration and any approach control already factored in.

 

[Rhydgaled]

I suppose that with the faster journey times, there's your fast train for Carmarthen right there.

Where? The IEP-worked London service? Nope, still takes 1hr 48min to reach Cardiff according to the DfT diagrams Excel spreadsheet*. Also, it isn't timed particularly usefully.

At least on the present IC125-operated timetable the morning service leaves at 07:30 (06:23 on the DfT's IEP diagrams), which looks to provide a well-timed service for Swansea commuters (this is the exception to my rule that everything going into Swansea High Street should terminate, as the capacity would probably be useful at that time and I don't see the Wales franchise being able to provide a sufficently long train).

* In fact, at that timing, the SDL (which I estimate at 1hr 23mins with a 158) is 25 minutes faster rather than 15.

 

[cmjcf]

(which I estimate at 1hr 23mins with a 158)

What's your basis for this estimate?

 

[Rhydgaled]

What's your basis for this estimate?

Using the East Coast / First Great Western journey planners and adding times for traversal of the SDL to those for non-stop Carmarthen-Llanelli trips and Manchester services doing Port Talbot - Cardiff.

Carmarthen - Llanelli is 22 mins (the Fishguard boat train used to be timed to do this, and there's an early-morning service that still is)

Llanelli - Port Talbot Parkway (SDL) is 28mins (32 in the other direction for some reason)

Port Talbot - Cardiff it seems can be come in between 30mins (one westbound service on Saturdays) and 34 (eastbound trains). That averages out at 32mins.

22 + 28 + 32 = 1hr 22mins, plus one minute dwell at Llanelli gives 1hr 33. With the SDL being slower in the other direction we have 1hr 37 total, or 1hr 35 if the 30min Cardiff - Port Talbot run can be achieved regularly.