[frinkprof]

Originally Posted by 19Yzerman19

You know, amidst all the crazy, the thing about turning around every 3rd C-Train during high traffic times rather than letting it go to the end of the line nearly empty might make sense if it's physically do-able.

This was proposed in a post on CP a few months ago. Not possible. Here's my reply.

Short turning [...] at non-terminus stations is difficult due to the frequency of trains and the track infrastructure in most of the system.

It might help to observe how a terminus station operates during rush hour for, say, 20 minutes or a half hour. How it works is that each terminus station has a preferred side that the train will pull into if it is available. This preferred side is the inbound side of the platform (if it were a non-terminus station). Before the train pulls into the station, it will use the crossover to switch sides and pull in, the driver switches ends, and then it is already on the correct side and can just pull out of the station when the driver has gotten to the other side and the train gets clearance. If another train arrives at the station while the preferred side is occupied by a train, it will pull into the other side and do its crossover when it goes back inbound.

Very often during rush hour, there will be trains on both sides of the platform, and once in awhile a third train will show up and have to wait a short time for the train on the preferred side to clear the station and crossover area. It's not for very long that one side of the platform sits empty. From what I recall hearing from a few operators is that a short-turn usually takes 3 minutes from when the train enters the crossover until it is pulling back out of the crossover.

The problem with doing them at middle-of-the-line stations is that, even if you could do it in 90 seconds, chances are you would be holding up a train either behind you, or the train coming the other direction (the direction in which the train would be turning around to head). Also problematic is the location and number of crossovers, and especially double (scissor) crossovers. As can be seen in the (old) track diagram in spoilers below, crossovers aren't in the vicinity of many stations, and of those that are, many are not in front of platforms, as would be needed to short turn.

The time it takes to short turn, and the problems it can cause for other in-operation trains in the vicinity, is actually the reason that the direct-to-NE trains that used to be run after Flames games and other Saddledome events is no longer done. What used to happen is that a train would wait at the other platform at Victoria-Park Stampede (called "C platform"). It would load passengers, head downtown, short turn at City Hall Station and then head to the northeast.

Also, even if you could do a short-turn that didn't effect train traffic, 7th Avenue is still the bottleneck and you can't fit anymore trains along it during rush hour. Once the train short-turns, it just arrives at 7th Avenue earlier than it otherwise would and either it or the next train would be waiting to enter and no net gain is made.

Finally, the short-turning-at-non-terminus-stations suffers from the same problem as the variable trains idea. Confusion has a cost.

Spoiler!

Excerpt from this post:

http://forum.calgarypuck.com/showthr...00#post4284500