Transit
Metro's buffet line effect: Proceed directly to dessert for best results
When a Metro car breaks down or becomes otherwise delayed on the Metrorail system, it creates a logjam of trains behind it. Even after the incident clears, it can take over an hour to return service to normal. Metro could speed up this process with strategic use of express trains.
With only two tracks on each line, it is difficult or impossible to reroute the trains that are behind an incident, and trains can't pass each other. Once the issue is resolved, the trains continue to follow each other one by one. But the first train is the slowest, already crowded with a crush load of passengers before arriving at one overcrowded platform after another. At these stations, people take longer to board and deboard. Each stop becomes a two-minute drill for just 20 or 30 people to squeeze on and off the train. In many cases the vast majority of people on the platform can't even get on and have to wait one or two or three trains to finally board. It can take a couple of hours for all the trains to move through the system and return service to normal.
This resembles a restaurant buffet line, which always moves not at the speed of the average diner, but at the speed of the slowest diner. Everyone backs up behind the one person who is carefully scrutinizing each and every offering. Relief finally comes when they move off to the dessert table and the whole line speeds up.
The simple and easy solution to the Buffet Line Effect is to express the trains after a delay. There are miles of empty track in front of the first train. If the trains that are backed up express forward to fill in the empty space, then normal service can return within minutes rather than hours.
This will, of course, inconvenience some passengers whose stations the train will skip. They either have to deboard and wait for a later train, or backtrack to their station. However, I believe that the overall savings for passengers will be much, much larger than the inconveniences. Given the capacity stresses Metro is experiencing on a regular basis, simple, no-cost solutions like these need to be part of their short-term strategy.
To do this well, though, requires two things: intelligent dispatching and excellent communications with passengers. Let's try an example.
Assume a breakdown at Gallery Place on the Red Line to Shady Grove. A mechanical breakdown causes a 20-minute delay and a train is taken out of service. There are now 5-6 trains backed up behind, probably out past Union Station. The track is empty from Gallery Place to beyond Friendship Heights, and the platforms are filled to overflowing in the downtown area.
First train: Skips Metro Center and stops at Farragut North (which has a center platform). The dispatcher has been alert and makes sure a train going the other way arrives immediately or is waiting for this train. Riders for Metro Center can choose to wait at Gallery Place or backtrack from Farragut North. The train then expresses to Bethesda. The train operator will have to clearly and constantly communicate to his/her passengers throughout this whole process, allowing everyone to make decisions about how they are going to deal with it. A train immediately arrives or is waiting at the platform in Bethesda for passengers to backtrack.
Second train: Services Metro Center (at the same time the first train is servicing Farragut North) and then expresses to Van Ness (with a center platform). Similarly, the dispatcher makes sure there is a reverse train ready to take passengers back.
Third train: Services Judiciary Square (while the first two are servicing MC and FN). Skips Gallery Place and Metro Center and services Farragut North like the first train. The dispatcher makes an informed decision about skipping another stop to create breathing room behind or allowing the train to proceed as usual. If this train is going to create its own "buffet line effect," then it should express ahead to allow the faster trains behind to proceed normally.
Fourth train: Services Gallery Place and Metro Center and proceeds normally from there, possibly skipping Farragut North if the third train skipped Dupont and created space (and also to get the riders at Dupont, who have now watched three trains go by).
How about those riders at Dupont who watched three trains go by? In the universe we inhabit now, most of them would have had to wait for two or three jammed trains just to board. And those trains would have been progressing at "buffet line effect" speed. In the end, they probably reach their destination just as fast. The overall system is returned to close to normal service within fifteen minutes, with trains more evenly spaced along the tracks rather than bunched together behind a dysfunctional, overcrowded train. It helps to imagine looking down on the system from above. It makes absolutely no sense to have 8 miles of empty track followed by a "buffet line" bunch of six trains clunking along at half speed.
Obviously, the exact best way to deal with any delay will vary every time, based on how long the delay is, time of day and other variables. This is why it requires intelligent dispatching and on-the-spot decision making to maximize the value.
The other requirement is courage. If Metro were to put this into effect, they need to do so consistently for a solid six months or longer, to allow riders to get used to it and to realize that they are actually getting better service than the current dysfunctional way of dealing with delays. They have to have the courage to stand up for the vast multitudes who save five or seven minutes against the vocal few who might lose fifteen or twenty on a single occasion and then complain. I don't know if Metro has the courage to do that.
 | Steve Offutt has been working at the confluence of business and environment for almost 20 years, with experience in climate change solutions, green building, business-government partnerships, transportation demand management, and more. He lives in Arlington with his wife and two children and is a cyclist, pedestrian, transit rider and driver.   |
Comments
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by Michael Perkins on Sep 16, 2009 10:56 am
by Michael Perkins on Sep 16, 2009 10:56 am
by David Alpert on Sep 16, 2009 11:00 am
by Mike on Sep 16, 2009 11:07 am
by Pedro on Sep 16, 2009 11:07 am
by DCDave06 on Sep 16, 2009 11:08 am
http://comedians.comedycentral.com/louis-c-k-/videos/louis-c-k----new-york-city-subway
by kidincredible on Sep 16, 2009 11:11 am
by beatbox on Sep 16, 2009 11:19 am
by Reid on Sep 16, 2009 11:22 am
Therefore, I don't expect it to get implemented.
by spookiness on Sep 16, 2009 11:26 am
by NikolasM on Sep 16, 2009 11:29 am
I have seen trains (at different times) skip West Hyattsville, Prince George's Plaza, and College Park.
I doubt you'd ever convince Metro to skip a transfer station, though.
I've also seen what you describe done in Chicago. In that case the train in question skipped multiple stops.
Additionally, I've seen MARTA (Atlanta) turn back opposite-direction trains during major delays. So under the described scenario, a train headed toward Glenmont might cross over at Dupont and return to Shady Grove. And it would have the advantage of being empty.
by Matt Johnson on Sep 16, 2009 11:33 am
It is better than the idea that always seems obvious to me, which is to create to two cells of trains before and after a stuck train. That is to say that trains who end up waiting behind a stuck train find the closed change of tracks and return back to their origin. Similarly, train that "run into" the stuck train turn around to.
The good thing is that this way the entire line keeps running, except for the station (or two) where the train is stuck. Furthermore, you do not end up with a lot of bunched trains waiting in one location, while the rest of the line is depleted of all those trains.
The bad side if though that it completely messes up the stock of trains. Trains end up where they are not supposed to be. And rail supervisors tend to not like that. Another disadvantage is that nobody can pass the place where the train is stuck, not even people traveling in the opposite direction.
Anyway, Steve's idea is way better.
In fact, when trains do get stuck, I tend to travel a couple of stations "upstream", to prevent having to wait 3 trains because they're all full.
by Jasper on Sep 16, 2009 11:37 am
by Alex B. on Sep 16, 2009 11:54 am
The communication challenge is not too different from the color-scheme debate that happens periodically. We're still looking for an effective way of conveying schedules and routes using mechanisms no more complex than a unique route-color and destination.
by HM on Sep 16, 2009 11:56 am
As have I. But only when the line is completely closed and trains are not able to pass in either direction.
For instance, the June 22 accident.
But I've never seen a train offload and change direction for a temporary delay (like brakes in emergency or sick passenger).
by Matt Johnson on Sep 16, 2009 11:59 am
Great idea Steve! Which is exactly why this will never happen.
by JTS on Sep 16, 2009 12:07 pm
But the experience seriously pissed me off, if Metro is going to skip stops at rush hour they should skip lightly used stations not busy ones. In my case, it would have made sense to skip the convention center or Shaw/Howard (or both) having ridden that line north at rush hour for three years I can say that neither station gets that much traffic. U-Street, by contrast, is usually pretty busy. So, if metro were to implement this idea, there should be a list of stations that never get skipped.
by Steve on Sep 16, 2009 12:19 pm
Simple algorithm, so no heavy mental lifting required by Metro.
by James on Sep 16, 2009 12:22 pm
I predict Metro will review this suggestion for the next 3 years before deciding it can't do it.
by Fritz on Sep 16, 2009 12:26 pm
by tom on Sep 16, 2009 12:32 pm
The first section would be "blockages during peak periods," the second "blockages during normal periods," and the third "blockages late night."
Within each, there would be a list of all 100+ stations. Under each station, there would be three headings: "shut-downs under 10 minutes," "shut-downs 10-25 minutes," and "shut-downs over 25 minutes."
Then, under each of those, it would tell each train, by number in line, which station to express to.
Here's an example that would be referenced by a dispatcher for actions to be taken by the second train in an example like Michael's, for a 20-minute shut-down mid-day:
* Blockages during normal periods
* Gallery Place Station
* Shut-downs 10-25 minutes
* Train 2 Route: Metro Center; Van Ness; local normal
by Joey on Sep 16, 2009 12:37 pm
by shaun B on Sep 16, 2009 12:46 pm
That's what I was trying to say. I was on a train that was offloaded to turn around because of a sick passenger.
by Alex B. on Sep 16, 2009 1:21 pm
by kenf on Sep 16, 2009 1:45 pm
I think that's better because (1) it's simpler to explain over a PA and (2) it acts most quickly to restore trains to normal headways. When you're doing this, it should be in a situation where there's another train immediately behind, so there's no particular need to serve the most popular stations from the first train.
by Josh B on Sep 16, 2009 1:54 pm
by Michael Perkins on Sep 16, 2009 1:54 pm
by NikolasM on Sep 16, 2009 2:03 pm
by Ward 1 Guy on Sep 16, 2009 3:00 pm
by RT on Sep 16, 2009 5:21 pm
They need to do something with the words they use in there messages.
A few minutes does not mean 10 minutes.
A train is right behind this train I should be able to see the train or at least lights if were on a straight piece of track.
Right behind does not mean 5 minutes away.
Another thing is that when trains are traveling to whatever destination and then the train out of nowhere changes to a new destination; the passengers on the train aren't notified really. I have been on numerous trains where they have just suddenly changed the ending station and many did not know about it heard the operator say train going to X instead of Y and figured it out while others were just confused thinking didn't he just say we were going to Y
How about keep repeating changes more than once keep saying that a train is changing from the normal course for about 2 or 3 minutes so that you can assure people have heard the message; depending on how many people are on the train and if its inside or outside you can not always hear everything.
I think that metro should offer discounts when it is there fault; such as if a train breaks down or station has a problem like electricity. It is a problem on there part was not due to a passenger disruption they should give 25 cents off the fare price.
Perhaps like when some stations were closed
or in the case of wheelchair when the elevators aren't working and they run shuttle buses sometimes the fare is higher by traveling to the other station that they say go to.
by kk on Sep 16, 2009 5:28 pm
by Matthias on Sep 16, 2009 6:17 pm
by Jamie on Sep 16, 2009 6:51 pm
If the in-car signage was in every rail car and more flexible so it could be overriden either by the operator or centrally to indicate stops being skipped and what the next stop would be, I could see the communications being good enough to do this though.
But yes, after incidents at least, they absolutely should implement a plan like this.
by Kelly on Sep 16, 2009 11:20 pm
My own observations of service disruptions suggests that they don't really have any plan--they seem to be much more reluctant than I would be to turn trains on either side of a disruption, and instead just try to put every train through a single-tracking area. None of it seems to be as efficient as it could be, but perhaps that's just my frustrations at being delayed coming through.
by thm on Sep 16, 2009 11:36 pm
It failed from the information perspecive. There was no obvious plan for us (customers) to follow. The to-be skipped stop wasn't anounced until the train was at the immediatly prior station, causing confusion and hurried exits.
So there is need for tight coordination and information flow as described in the post, but who needs this information? How is it passed and used?
Central (make informed decisions)
Operator (pass to customers on the train, train signboards)
Station Manager/PIDS (pass to customers on the platform)
Website (customers planning to use Metro)
Management (performance measurement and lessons learned)
Are there other ideas? I want to see Metro succeed and I'm glad there are others out there.
by chuck on Sep 17, 2009 1:03 pm
I, too, used to live in Philly and think this is worth trying here.
by Steve O on Sep 21, 2009 12:13 am
While waiting for the Orange line to VA this morning, I heard so many confused passengers asking about where trains was headed.
Person: "Is this train going to Federal Triangle?"
WMATA Person: "Yes, it is headed east toward Virginia."
Other Person, who overheard conversation: "Wait does, that mean it's going to Farragut West too?"
Me: (slaps forehead)
Five minutes later when the train actually arrives.
Another person down the platform asking me: "Do you know if this train stops to Federal Triangle?"
Me: "Yes. It does."
Evesdropper asks me: "Wait, I thought it was going to Ballston"
Me: "Yes, it's going Ballston by way of Federal Triangle. It's the same direction." Me thinking: "doofus."
If regular riders can't even understand the concept of East-West, how do you expect them to get the idea of pulling a U-turn on the Red Line without getting frustrated, angry riders? It's not patronizing, but realistic. Some people are just plain geographically challenged...and I don't think Metro will want to put up with all those disgruntled people.
by SDJ on Feb 12, 2010 2:30 pm
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