As per post 25. Possible track geometry drives maximum speed. The line was originally built single track, low speed in a very constrained site (that is now a SSSI). There's not a lot that can be done without politically- and environmentally-sensitive land take.
Nor really. Bear in mind the line runs down the Avon Gorge squeezed between the cliffs and the river. Taking land on one side means gouging bits out of the cliff (the sensitive bit environmentally). Saying you've now left a 3m (or whatever) strip of former railway between the new formation and the river bank is hardly replacing like with like.
The thing is, the right place for a loop requires extensive civil engineering works in an area not suitable for it (see Brissle Girl's post).
I suppose the problem with a loop at Pill is that it would require two new platforms, with the additional expense entailed. However a loop between stations is ideally a pretty long and expensive 'dynamic' affair in order that both trains can enter and pass at speed, rather than one direction having to make an additional stop to wait for the other.
The main problem with a loop at Pill is that it’s in completely the wrong place, being reached no more than 5 mins after leaving Portishead. (We can expect the rebuilt section of line to have “normal” running speeds.) You can’t design a sensible timetable around that.
Understand and agree a long turn round layover at Portishead would mean a half hour service would probably require an extra unit over a plan with the passing place in a better place. Also requires expensive provision of two accessible platforms at Pill which the original plan didn't envisage. An advantage of a long layover might be greater resilience to recover from previous late running, but probably not quite long enough to schedule a crew PNB there. Is the preferred option to extend double track from Ashton Gate further to the passing place or provide an extra loop at the appropriate site?
I agree, build it while the going is good. The line used to be double out from Ashton through Ciifton Bridge station and beyond there was a siding. Then, after that, only about two miles westwards, there was a long loop at Oakwood just east of Ham Green Halte. Then a bit further, the line was double through Pill onwards and there were further sidings towards Portbury, which leaves room for more doubling.
Which contradicts the view that only running at 30mph will make the whole service unattractive. We’ve waited long enough, let’s get it built and hopefully its success will justify the funds to improve it. And even if not, two 4 car services arriving just before 8am and 9am will still provide 600 seats and a few more standing, which will reduce congestion and emissions on the Portbury Hundred and onward into Bristol.
It's being designed for 5-car.
That would need a very long platform to accommodate two five car trains and a mid position crossover.
Even better then. A 165+166 would give around 450 seats, so 900 with two arrivals between 7am and 9am. Now I expect some of those will be commuters that previously used the bus, but still a major environmental improvement. And will ease congestion for those not travelling into central Bristol too who still need to drive - a point that I suspect is often lost by those considering the benefits.
They are already 2 tph in the peak, which seems adequate given the number of pax (which is increasing quite quickly it has to be said).
