Wider service possibilities following the Portishead reopening?

Snow1964 said:

I tend to think should have made the station platforms nearer 170m long, so that they could run 8car EMUs (if ever electrified) or BEMUs, or pairs of 3car DMUs on busy event days. Especially as the Arena and Football ground (and Cricket ground, and balloon festival) are all likely to have busy days.

The idea that 120m platforms with short trains and an hourly service will cope seems misguided, if add in surrounding towns, Bristol area is nearer half million people. So building a system with capacity of just 280 seats an hour sounds tiny.

It appears the plans for all the Burns stations in South Wales have 170m platforms to cope with rush hour and event days, and some of those trains will continue to Bristol area.

It sort of feels opted for bare minimum, with no serious provision to encourage those travelling to Bristol for events to use public transport

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It was literally to save money as and where they could. The good thing is Pill is using the existing platform so that could easily be extended. Portishead in due course could be if required - i think a half hour service over longer platform would be the preferred one for me. They are at least redoing the signalling with that in mind - they would just require implementing a passing loop. The logical one would actually be the one past ham green half where the track bed is still wide enough.

Ran along the route today (well up to pill from Portishead anyway) but not too much to report on - bridge work on sheepway is well underway, the compounds for track work are underway at marsh lane and Portbury hundred. Other than that and the existing work at Portishead station / road reworking station not much else just yet

tumbles said:

i think a half hour service over longer platform would be the preferred one for me

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If patronage is sufficient for either, it probably needs both.

Zomboid said:

If patronage is sufficient for either, it probably needs both.

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I don't think it's ever going to need that level of capacity - the Severn beach line on the other side of the river, covering a lot more urban areas, copes fine with 3 car 166's most of the time, but with a half hourly service. The other issue would be rolling stock, it's already stretched on current local services before you start adding in the Portishead line. Wishful thinking that they'd bring some D stock/230's running along it.. or maybe they'll have fixed the 175s by then..

tumbles said:

I don't think it's ever going to need that level of capacity - the Severn beach line on the other side of the river, covering a lot more urban areas, copes fine with 3 car 166's most of the time, but with a half hourly service. The other issue would be rolling stock, it's already stretched on current local services before you start adding in the Portishead line. Wishful thinking that they'd bring some D stock/230's running along it.. or maybe they'll have fixed the 175s by then..

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If all services were 3 cars, it would probably be fine, but with the 2 and 3 car mix it struggles. At Peak times it could easily fill 4 cars, although for just 2-3 services in the mornings and evenings that's rather a lot of investment for the relative need.

I think half-hourly would be the priority for Portishead, over platforms >126m.

I suppose what I was getting at was that frequency drives demand, so if a half hourly service were justified then it's quite likely that short trains wouldn't cut it.

Might have over-egged that, though. Portishead isn't that big. The higher frequency would be a much better service for the prospective users than hourly longer trains though, especially on a suburban operation. 2 tph should really be the minimum for something like this.

Not everyone going to Arena events will be needing Portishead services. During events I imagine the Portishead services can be complemented by an additional 2tph running into Temple Meads, with one of them possibly extended to Weston-super-Mare or Westbury depending on demand.

Zomboid said:

I suppose what I was getting at was that frequency drives demand, so if a half hourly service were justified then it's quite likely that short trains wouldn't cut it.

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Frequency does drive demand, but obviously if you are running services every 30 minutes then your travel demand is split over 2 train (although probably not evenly). A 3-car every 30 minutes would likely cope better with the equivalent traffic than a 5-car every hour.

Zomboid said:

Might have over-egged that, though. Portishead isn't that big.

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Portishead is about 20,000 or so, although a good chunk of that is on a bit of limb away from the station. Pill is only a village, and won't be a railhead given the proximity of Portway to anybody on a car. And there's nothing else between Pill and Parson street to serve.

Zomboid said:

The higher frequency would be a much better service for the prospective users than hourly longer trains though, especially on a suburban operation. 2 tph should really be the minimum for something like this.

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On a suburban, 30 minutes is indeed the desirable minimum. However, I'd argue that given the direction the project was going, a 60 minutes service is far better than none at all. Putting in the loop at/near Pill for half-hourly would have pushed costs beyond the point of justification.

Get the line in, get some actual figures on it, and then rerun the numbers for 30 minutes. In any event, at hourly or half-hourly the line is likely to only be standing room only for 6hrs a week (Tues-Thurs AM and PM peaks).

zwk500 said:

a suburban, 30 minutes is indeed the desirable minimum. However, I'd argue that given the direction the project was going, a 60 minutes service is far better than none at all. Putting in the loop at/near Pill for half-hourly would have pushed costs beyond the point of justification.

Get the line in, get some actual figures on it, and then rerun the numbers for 30 minutes. In any event, at hourly or half-hourly the line is likely to only be standing room only for 6hrs a week (Tues-Thurs AM and PM peaks).

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Absolutely. Build what you can now and expand in future if justified.

Hopefully design the loop now so that nothing is done for phase 1 which then has to be undone to build it...

Manutd1999 said:

I would propose a total of 7ph:
2ph London as-today, 3ph semi-fast to Portsmouth/Weymouth/Oxford and 2ph all-stop to Westbury. This should be (just about...) do-able.

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What about the freight traffic which runs, how would that fit with the increase in passenger service on that section which pretty much fills up the line.

Zomboid said:

Hopefully design the loop now so that nothing is done for phase 1 which then has to be undone to build it...

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In terms of signalling they have already provisioned for a passing loop, which is good. Because of the track limits (30mph after Pill Station to Parsons Street) the logical place is the old loop that is just past Ham Green Halt - https://maps.app.goo.gl/e91jhdF8zQxcAcfX7 the trackbed is still wide enough/in situ.

Is Parson Street's third platform (heading towards Bristol) being reinstated as part of the line's reopening? If it is this would be handy for keeping Bristol-bound trains off the main running lines so can be pathed more easily around fast services.

brad465 said:

Is Parson Street's third platform (heading towards Bristol) being reinstated as part of the line's reopening? If it is this would be handy for keeping Bristol-bound trains off the main running lines so can be pathed more easily around fast services.

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Probably. I haven't seen the precise project information so can't say for sure, but given that the junction is going to have to be made passenger-rated, it would seem to be easier for the project to just get the Up Relief passenger rated at the same time, rather than try and be very awkward about forcing all passenger services to use the Up Main briefly, especially given the position of the signals around Parson Street.