Quote:
Originally Posted by aberdeen5698
It doesn't matter what the fleet size is. With an automated system there are no drivers to pay, so there's no penalty for breaking your fleet up into smaller trains that run more frequently. The only time you need to increase the size of the trains is when passenger loads have justified buying so many trainsets that you've already reached minimum possible headways. And you'd only need to increase the size of the stations when trains at their maximum lengths and minimum headways are unable to service demand. And even at that point it might make more sense to build an alternate line instead, given the greater connectivity, coverage and network benefits and relatively smaller incremental cost (i.e., the cost of building the new line avoids having to pay for expanding the stations).
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Exactly.
Quote:
Originally Posted by aberdeen5698
I'm speaking in general terms, of course. A Skytrain extension to Langley would share Expo line trains, and the Expo line is getting to be capacity constrained at the downtown end- which means it's mostly grown to using the longest trains that the stations can accommodate.
But I can't imagine it being capacity constrained at the Langley end. In theory, you could run smaller trains at that end of the system - for example, you could have two-car trains that shuttle back and forth between Langley and King George while a separate set of longer trains runs between King George and downtown. That would provide more frequent (and therefore better) service for people on the outer edge of the system. It would also have the advantage isolating the two segments so that problems one one wouldn't affect the other (although that isolation could also be done dynamically as and when needed).
That would force Langley-bound passengers to switch trains, but the high frequencies and the simplicity of just having to walk across the platform would minimize the pain and the delay.
In practice, though, I suspect it's unlikely that an extended Expo line would be operated that way - what would probably happen is to short turn every other train or perhaps 2/3 of the trains at King George. That would result in less frequency on the Langley segment, which would mean poorer service.
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We don't really know how many people would be taking Skytrain in Langley as they don't have anything comparable now. There may well be loads of people who would take it to Surrey Central (which is why I'd have the trains short turn past that - both Gateway and Scott Road are options). Even if they had to wait comparable times to what the Millennium Line does now, it would still be an improvement over what they have.
Plus I said short turn trains from both ends of the line. Maybe for every 3 trains from Waterfront, 2 are short turned and 1 continues through to Langley. Also for every 2 trains from Langley, 1 is short turned and 1 continues through to Waterfront. Keeper shorter trains in Surrey and Langley (a Mark 1) while the through train would be longer (a Mark 2 or Mark 3).
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