Slowdown between West Oakland & 12th Street
I have always wondered why northbound trains slow to a crawl (and sometimes a stop) between West Oakland and 12th Street. I understand being a little slower entering the tunnel, because of the derailing accident (which I wasn't around for but which has been detained on this blog), but I am talking about way before that, when the train is still on overhead tracks.
It wouldn't be such a big deal (besides my curiosity) but during rush hour, the trains are all still really crowded and uncomfortable by that point, and the sun shining in makes the hot and stinky -- so all you want is the train to hurry up and move its @$$ to get underground, out of the sun.
I figure there are enough people with enough knowledge here to easily answer this question.
Because of the tight radii of
Because of the tight radii of the track in the Oakland Wye A05 interlock (the triangle of track connecting 12th St, W. Oakland, and Lake Merritt stations), all trains have a maximum speed limit of 18 MPH while in the Wye to prevent derailments instead of the usual PL2 max of 80 MPH on straight and dry rail.
I think he's actually
I think he's actually referring to the elevated portion directly east of West Oakland but before the Wye. I don't think there really are any interlocks until just before the tunnel begins.
You're right, but the
You're right, but the question where does the 18 MPH speed restriction begin. I don't know this. However, there is the M03 interlock where the two tracks from West Oakland split into 3 tracks before A05 (the Wye). I know they've had some problems with M03 recently, and that tends to hold up trains going into the Wye. His train also could have been on SORS (i.e. another train ahead on the same route) as well.
Does the 18 MPH speed
Does the 18 MPH speed restriction apply to the PBP trains at the M03 interlock? I've noticed that the Pittburg/Bay Point train will cross the 2-to-3 switch at reduced speed, then suddenly accelerate and gain speed before entering the tunnel into 12th St.[Platform 1]. But the Dublin/Pleasanton and Fremont trains enter at reduced speed, go into the Wye maintaining that speed until it merges with the track coming from 12th St.[Platform 2] and then increases speed only a few seconds before entering Lake Merritt.
This thread is awesome.
This thread is awesome.
Wide gauge rail has a wider
Wide gauge rail has a wider turning radius, narrow gauge has a narrower turning radius (this is why you see narrow gauge rail in the hills, and mine shafts, it is so they can make sharper turns ).
In BART's case, their use the wider gauge rails prevents the trains from making the sharper turns in some of their tunnels. Thus the reduced speed.
Half of me seconds this
Half of me seconds this statement. (That this thread is awesome.)
The other half of me wants to know why when I'm on a Richmond train it's way slower through this section than a PBP train. When I miss my Richmond train and I catch the following PBP train (during afternoon commute out) I sometimes catch up to the Richmond train at MacArthur (the one in front of me, not the transfer). I'd wager the Richmond trains are going slower than 18 mph through that curve going underground in Oakland.
Probably a timing issue. The
Probably a timing issue. The trains can't actually leave a station earlier than the scheduled time. And many trains are deliberately timed to help people transfer from one line to another. It could be that in order for the Richmond train to be timed correctly they needed to slow it down a bit somewhere along the line, and the Y is a good spot to do it. Or, similarly, perhaps the slow down is to allow another train, on its regular schedule, time to pass through the Y without the two trains crashing into each other (timing it so the Richmond train can just slow down instead of coming to a stop).
The other thing I'm thinking is that it could have something to do with how the wheels are worn. My understanding is that you can't take a train that's normally a Fremont/Richmond and stick it on, say, the SF/PBP line, because the wheels are worn by the tracks in such a way that switching could lead to the train derailing (and I think this was the reason behind one of the big derailments that happened many, many years ago). Perhaps the way the wheels are worn on the SF/Richmond line make it so that the train has to slow a little at that spot to avoid a derailment.
> The other half of me wants
> The other half of me wants to know why when I'm on a Richmond train it's way slower through this section than a PBP train. When I miss my Richmond train and I catch the following PBP train (during afternoon commute out) I sometimes catch up to the Richmond train at MacArthur (the one in front of me, not the transfer)
From 12th Street to MacArthur, the PBP track is quicker than the Richmond Track. The PBP track gets a section of 50 mph track (after 19th), while the Richmond track is always 36mph (or less). In general, whoever gets to 12th street last gets to go first. That's usually the PBP train. The Richmond train travels from Fremont, and winds up about 3 minutes behind the Dublin train going to Daly City (or Millbrae). About the only thing that can delay them is a police action. The ridership is usually light enough so door dwells are short. However, the PBP train has to come through the city and has more opportunities for delays. Usually, the PBP train is last.
Officially, the northbound transfer is only guaranteed at 12th street (although the announcements don't make this clear). Since the PBP train is usually packed, the TO often prefers to do the obligatory meet at 12th and try to avoid an informal meet at 19th and MacArthur. This just delays an already late train even more.
> Probably a timing issue. The trains can't actually leave a station earlier than the scheduled time.
Well, they are not supposed to. But a TO can program a run thru and get out of there a bit sooner. A TO is not supposed to program this without permission from central, but during the commute, it isn't going to be noticed. Some TO's are notorious for this, but realize that half the controllers used to be TO's and their classmates are still driving trains. And, if a train is stuck waiting for a release, and the radio is jammed with traffic about an incident far away, a TO will program a run thru on his own.
> And many trains are deliberately timed to help people transfer from one line to another. It could be that in order for the Richmond train to be timed correctly they needed to slow it down a bit somewhere along the line, and the Y is a good spot to do it.
A Richmond train that is on time, will come through the wye on PL6.
> Or, similarly, perhaps the slow down is to allow another train, on its regular schedule, time to pass through the Y without the two trains crashing into each other (timing it so the Richmond train can just slow down instead of coming to a stop).
Out of service trains are often given PL4 or something slow, so it isn't dogging a revenue train and stopping on SORS every few miles.
> The other thing I'm thinking is that it could have something to do with how the wheels are worn. My understanding is that you can't take a train that's normally a Fremont/Richmond and stick it on, say, the SF/PBP line, because the wheels are worn by the tracks in such a way that switching could lead to the train derailing (and I think this was the reason behind one of the big derailments that happened many, many years ago).
Actually, trains get "stolen" often. For example, a dead Dublin train will get replaced by one of the commute trains (the extra trains on the PBP line). And, once a year, the fleet gets turned, so the cars face the other way.
So I probably didn't explain
So I probably didn't explain what I've pulled off (and I think a few other afternoon Richmond commuters have done too). If I miss the Richmond train and there's a PBP immediately behind it about 1 times in 4 I can catch the Richmond train that's in front of me (originating from Millbrae, not Fremont). I can't ever pull it off at 12th, but usually by MacArthur. But none the less, you've addressed what I've experienced - the PBP train gets a higher speed limit than the Richmond while going from West Oakland to 12th. Now, why that is, is another question.
Isn't the equipment on the
Isn't the equipment on the Richmond line primarily the older sloped front end cars instead of the double headed flat front cars on the other lines? Equipment age may make a difference in the speed limit.
> the PBP train gets a higher
> the PBP train gets a higher speed limit than the Richmond while going from West Oakland to 12th. Now, why that is, is another question.
A small stretch of track between 19th and Mac is 50 mph.
> Isn't the equipment on the Richmond line primarily the older sloped front end cars instead of the double headed flat front cars on the other lines? Equipment age may make a difference in the speed limit.
The "older" sloped (A) cars are actually newer. All the A and B cars got rebuilt recently. But, all the cars travel the same speed. A C-B-C train gets to Richmond in the same time as an A-B-A (or even a CCCCC) !