(02-19-2018, 11:09 AM)Canard Wrote: Trailing-point half-crossovers like ours are inherently safer - a mis-thrown switch doesn't have the possibility of leading to a head-on collision between vehicles, like leading-point half-crossovers do.
There's no need to have full-full crossovers, either, unless you want to reverse-run for a short section of a route due to platform or track maintenance in a short section and have a pinch (not an issue when your headways are as big as ours, but that's another discussion...). Our system was never designed with that capability in mind (otherwise there would be full crossovers at much more frequent intervals).
The trailing-point setup we have will be just fine for ion. Simple, cheap, and effective - the motto of the entire system, really, and an excellent model for others to follow.
Indeed, and lately I’ve been wondering why (almost) all the TTC crossovers are double — I know some used to be terminal locations, but there are several that have always been nothing more than intermediate short turn locations and it’s not clear to me why they would ever use the facing-point half of the double crossover.
I was raising the issue in the context of somebody pointing out that each track could be used in either direction and therefore one should look both ways before crossing. Of course they are correct as a matter of prudent behaviour, but I’m wondering how often our trains will actually run in the opposite direction, given that the crossovers are not designed to make opposite-direction running convenient (except on the Spur Line of course).
Incidentally, I don’t understand why we have double crossovers and dual platforms at the terminal stations. It seems like just having the two tracks join into a single track just under one half of a minimal headway’s travel time from the end would work fine. One switch instead of four, no diamond, and a single buffer. Of course space should be left to extend the double track to the end of the line to allow for future extension.