Express trains:New York rush hour

My subway line (#6) runs from the Bronx to Manhattan (see link for map of NYC subway system). In the AM, some of the #6 trains make all the local stops, while some run express, skipping many stops, with a faster travel time to Manhattan. During the AM commute, trains running from Manhattan to the Bronx run local only. For the PM rush, this scheme is inverted; trains running from Manhattan to the Bronx run either local or express while those running from the Bronx to Manhattan are only local.

How can they do this? If the express trains have a faster transit time than the local, and the express runs in only one direction, why don’t they run out of express trains?

I have considered a few hypothesis:
[li]There are trainyards located in Manhattan that store the trains that accumulate in Manhattan (AM) or the Bronx (PM). This way, you’d have a surplus of trains in the right place. What I don’t like about this idea is that you need many extra trains and large yards in which to store them.[/li]
[li] Trains are sent back empty to the originating borough empty on the express tracks. But why would you do this? It would make more sense then to provide bidirectional express service.[/li]
[li] A #6 train (or any other line) isn’t always a #6 train. In other words, trains from other lines can be pressed into service to balance out the flow of commuters. But the trains have permanent signs inside them designating to which line they belong. This seems to be a long shot. Also, on train lines with unidirectional express service, the express service is into Manhattan in the AM and out of Manhattan in the PM. This should result in a lack of trains from all lines in outer boroughs in the AM and in Manhattan in the PM.[/li]
How do they make this subway magic happen?

Can’t the express #6 just become a local #6 on its return?

I think the #7 trains do the same thing.

Yes, they do. But the local trains make the trip more slowly. So they tend to be depleted from the side that the express trains originate.

And also, why run the non-rush hour trains local only if you need them to get back to the rush hour side? I can’t think of any disadvantage to running them mixed local/express.

They must just have enough trains so that depletion is not an issue.

Or they switch the signs and run them uptown as a 4/5 on the express track at rush hour. Since the 6 never leaves manhattan (the 4/5 going downtown heads out to Brooklyn) this would actually be very convenient, as it would provide many trains ready & waiting in Manhattan in time for rush hour.

I considered this (read hypothesis #3 from the OP). The problem is that the trains have very permanent looking signs inside of them. The new trains with the fancy high tech computer voice have the route maps with LED indicators depicting that stops that the train has made or will make. These signs (they are located in the same area of the train as the Budweiser and Dr. Zizmor ads) are permanent and only depict the #6 route) The older trains have the analog “roller signs.” I need to play with one to see if it changes to #5 or #4, but I think it only toggles between #6 express and #6 local.

Assuming that your idea is correct, a large storage area in the Bronx is still necessary to accomodate the extra trains required for the AM rush to Manhattan. There exist train yards in the Bronx (there’s one on the corner of Eastchester Rd and Waters Place for the #6), but I doubt it has sufficient capacity.

Okay. I reread the OP a few times to make sure I got the gist of the question.

I do not have a definative answer, but I do have some other possibilities that have not been considered. (In all the examples, I will deal with only the AM rush hour situation; reverse it for the PM rush.)

First: Maybe they do not have return (from M-to-Bx) express service specifically to keep the M-to-Bx-express-track clear so that thay can shuttle the express trains back to the Bronx – either to store them for the evening rush hour, or to use them for another AM Bx-to-M run. This method gets the trains back fast (no stops) and only requires a motorman - not a motorman+conductor team.

Second: I know there is no downtown M storage yard, but I know that they do store “extra” trains on unused tracks until rush hour; so, maybe those extra Bx-to-M trains are being stored on the unused M-to-Bx express-track until the evening rush. Or…

Third: …they’re being sent to a storage yard in Brooklyn, awaiting use for the evening rush.

Or, it’s a combination of all of the above.

For the AM. Every time a train reaches the Manhattan terminus, it turns around and leaves as a local. When a local train reaches the Bronx terminus, it turns around and sometimes leaves as express and sometimes leaves as local. They have less frequent local service from Bronx to Manhattan than the other direction during the AM. Or am I missing something here?

Doc, you wrote:

“…They have less frequent local service from Bronx to Manhattan than the other direction during the AM. Or am I missing something here?..”

Yeah, I think you’re missing something. Both the locals and expresses are running like gangbusters from Bx-to-M in the AM rush – far more, I think, than are retuning via the M-to-Bx local track.

The more I think about it, the more convinced I am that my first theory is right – namely that the’re running empty trains non-stop up to the Bronx via the M-to-Bx-express-track to commence another run into Manhattan ASAP.

I think DrMatrix got it. - the idea is to get people to their jobs fast.
The LIRR and Metro N save up trains for the rush hrs. This is very evident during weather related ‘evacuations’ that we have from time to time. The last one (last fall?) Metro N ran out of trains at about 2pm and had almost no service during the normal rush hr service.

Or, they may be running the trains back north on out-of-service track – usable track not currently on any subway line. As I’m sure you are aware there is quite a lot of track not currently in service. At this very cool site you can see info on abandoned stations, if you’re interested:

ps – there is another IRT yard at 207th street, its on the 1/9 but there are places to make the switch (as you are probably aware, IRT trains run on a different gauge from IND/BMT trains). And another yard on the 4 line at Concourse/Jerome (near the Bedford Park stop).

argh, wrong link. That link gives info on abandoned tunnels and connections. This link gives info on abandoned stations:

Akk! Time to correct an all-to-common piece of misinformation. (That even Prof. Ken Jackson, current Pres. of the NY Historical Society, got wrong, I’m afraid to say.)

rmariamp, IRT trains do not run on a different gauge from IND/BMT trains. All trains in the USA – with very rare execptions – run on the same gauge. (FYI, guage = distace between rails.)

The difference between the IND/BMT vs the IRT lines concerns tunnel diameter and/or rail curve radius. The longer cars on the IND/BMT lines can’t fit inside the IRT tunnels and/or negotiate the tight turns without scraping the walls.

As for unused track, I don’t think there is that much out there; most abandoned stations exist along currently-in-service lines – they were merely shut down due to low patronage at that particular station.

Aiii!! I stand corrected!! I knew that IRT were narrower & longer but did not suss that the problem was turn radius, not gauge. Actually, that’s very interesting. But the long & short is that IRT trains cannot run on IND/BMT track.

Yes they can (I saw a significantly out-of-place #5 train rolling down the A train tracks in the vicinity of 125th Street not too long ago and did a triple-take at it) but probably not vice versa.

re: the OP –

a) The distal terminus ends of the lines start off in the morning with a surplus number of trains in a conveniently located yard (such as the one out past Westchester Square on the #6 line). The surplus gradually deposits itself at a more central location in order to facilitate rush hour travel in the opposing direction in the afternoon.

b) For the lines that run express in only one direction such as the #6, the local trains don’t run the whole length of the track, with the exception of the rather weird #7 line. The #6 line, for instance, has its express trains starting at Pelham Bay Park, but its local trains start much closer to Manhattan at Parkchester. The trains returning from Manhattan can turn around at Parkchester; only a few have to make it all the back to Pelham Bay Park.

c) =>^^<=

Running IRT trains on IND/BMT track is the only way that the 7 could ever get to a train yard. They can’t run IND/BMT trains on IRT tracks, though.

Tomorrow I’ll see what I can find out over on the NYCsubway site. They’ve also got message board there, where you would definately get an answer.