Sunday, April 26, 2015

Going in circles on the Silver Line. Or, how the T could save $1m tomorrow.

In my last post on the Silver Line, I wrote about how the poorly-timed light at D Street causes unnecessary delays. If you're lucky enough to get across D Street, you then go through the power change at Silver Line Way and then begin the loop back to get on to the Ted Williams Tunnel to the airport (and soon, Chelsea). The end of Silver Line way sits right above the tunnel portal. But to get to that point requires a roundabout route, often in heavy traffic, which takes a full mile to return you right to where you started.

If only there were a better way.

There is.

After leaving the busway, the Silver Line outbound route goes down the Haul Road, merges in to a ramp from the Convention Center and D Street, and runs fully half the distance back to South Station—in mixed traffic—before finally turning on to the Turnpike towards the tunnel and the airport. What's the point of building a bus rapid transit corridor if you then spend the same distance sitting in traffic to get back to where you started?

What's worse, the "Bus Rapid Transit" endures two traffic lights in mixed traffic, and this traffic is often heavy, especially when when convention traffic from the nearby convention center spills on to the highway at already heavily traveled times of day. The route is more than a mile long, and in perfect conditions takes 3 or 4 minutes, but in heavy traffic can easily take 10 or 15; this traffic especially renders the "rapid" part of BRT useless.

Before entering this morass, there is access to the tunnel via a ramp next to a state police facility. If the buses could use this ramp, they would save three quarters of a mile of travel, two traffic lights, a yield at a merge and, conservatively, two minutes per trip. Combined with the potential savings at the D Street light, these two improvements could save 10% of the total round trip time between South Station and Logan—or Chelsea.

Now, perhaps there's a technical reason the Silver Line buses couldn't use the ramp. Maybe it was too steep for the buses. But in 2006, when part of the tunnel collapsed, the T was granted permission to use the "emergency" ramp to access the tunnel beyond the panel collapse. A Globe editorial from that summer praised the T for its quick thinking in utilizing this routing. Yet when the tunnel panels were fixed, the buses were rerouted to the roundabout course which brings them halfway back to South Station before they enter the tunnel.

MassDOT actually has these buttons.
Time to put them in to action.
There's obviously no physical reason this ramp can't be used, since it was used in the past. And any argument that the merge wouldn't be long enough to be safe is unconvincing, especially since it would only be used by a bus every four or five minutes, even when the Gateway project to Chelsea is completed. The in-tunnel merge has 1/10 of a mile before the lane ends, far longer than similar merges on to the Turnpike in the Prudential Tunnel. Suggestions that this would be unsafe are protective hokum; with appropriate merge signage (perhaps even a "bus merging when flashing" light) there should be no reason why this can't take place safely. The Transportation Department, MBTA and State Police need to convene to figure out the best way to use this facility, but the answer certainly should not be the usual "no," or "but we've always done it that way."

There's an environmental justice piece, too, especially with the extension to Chelsea, a disadvantaged city a stone's throw from Downtown Boston, but a slow ride away by transit. Right now, Chelsea residents are at the whim of the 111 bus—and the traffic on the Tobin Bridge. It seems foolish to build a brand new bus line to Chelsea but not to address one of the major bottlenecks on the rest of the route. If the Governor is serious about implementing reforms to improve service and save money, he should look beyond specious claims of sick time abuse and at where interagency cooperation could save time for passengers and time and money for transit operations.

Dr. Evil. Transit economist.
It costs the T $162 to operate a bus for an hour. The SL1 Airport service operates 128 trips per day, and we can reasonably expect that the Chelsea service will operate with a similar frequency. Fixing the D Street light and using this ramp could conservatively save 4 minutes for each of these 256 trips, which would equate to an operational savings of $1,000,000 per year.

Is this a drop in the bucket as far as the T's overall revenue is concerned? Sure, it's less than one tenth of one percent. However, it's a million dollars that could be saved, pretty much overnight, with basically no overhead investment. We spent more than half a billion dollars building the Silver Line tunnel and stations, and acquiring the buses. And the SL1 buses actually turn a (slight) operational profit! It's high time we removed some of the stumbling blocks it's saddled with and let it operate with a modicum of efficiency.


Saturday, April 25, 2015

Where could the MBTA implement unscheduled short turns?

I recently wrote about short turning a bus on the EZRide Shuttle route. People will ask: "why doesn't the T do this, my bus is always bunched?!" The answer is a) it's not easy to do, b) they are way too understaffed to do so, and c) their schedules are so much more complex that there are many more moving parts. At rush hours, the T has four dispatchers watching 100 buses; my office has one or two watching nine (although it's not our only job, sometimes it demands full attention). The need for short turns arises at times when there is heavy traffic and ridership. At those times, it's all the dispatchers can do at that time to keep some semblance of order among the 250 buses they're watching, not turn their attention to one particular part of one single route.

And also: there are only so many places and times you can successfully execute a short turn. Our route has a lot of twists and turns which make it easy for a bus to take a right instead of a left and go from outbound to inbound, but often a short turn may require a bus to go around a narrow block in traffic, and you certainly don't want a bus getting stuck on a narrow corner where it doesn't belong. There are more issues with the T: we know our drivers are on one route and that their shifts end around the same time. I've actually had times where a driver couldn't cover an extra run because he or she had to be at another job; this is more frequent at the T where shifts start and end in a very complex scheme and at all hours of the day; a driver might finish one trip and set out on a different route, so a short turn would find them far away from where they needed to be. And finally, the T has thousands of drivers, so there is no way for a dispatcher to know whether a driver is familiar with the route and where to make a turn, or whether it's his first day in the district and he or she is following the route for the first time.

Trains? Buses are much easier than trains. Trains require operators to change ends, change tracks—often at unpowered switches—and obtain a ton of clearance to do so, especially on the older sections of the MBTA system which don't have the kind of new bi-directional signaling systems that, say, the DC Metro has. If the T had pocket tracks in the right places, it might be easier. But without them short turns would only save time in a few circumstances and a few areas.

And on a train you're dealing with even more passengers. I've been on trains expressed from Newton Highlands to Riverside. Even with half a dozen announcements, a couple of stray passengers won't pay attention (buried in their phone, perhaps) and then wonder why the train is speeding past Waban. I've heard of crews at Brigham Circle, after switch the train from one side to the other, walking through the car rousing passengers who are on another planet (or just staring at their phones). If you can't run a short turn expediently, it's not worth doing at all.

That being said, I have a couple of thoughts on routes which could benefit from more active management and, perhaps, some short turns. Both are frequent "key" routes, both experience frequent bunching, and both carry their heaviest loads in the middle of the routes, so that the passengers from a mostly empty bus in the trailing half of a pair could be transferred forwards without overcrowding the first bus. The are (drumroll please): the 1 and the 39. Let's take a quick look:

Actual NextBus screen shot for the 1 bus.
1. The 1 Bus is one of the busiest routes in the system (combined with the CT1, the Mass Ave corridor has more riders than any other such route except the Washington Street Silver Line) and frequent headways of 8 minutes at rush hours. There is no peak direction for the route; it can be full at pretty much any time in any direction. And it is hopelessly impacted by crowding and traffic, such that bunching is almost normal, and on a bad day, three or even four 1 buses can come by in a row, with a subsequent service gap. (It could benefit, you know, from bus lanes and off-board fare collection, but those are beyond the purview of this post.)

But the 1 has a couple of features that make it a candidate for short turning. First of all, its highest ridership is in the middle of the route. The route runs from Dudley to Harvard, but the busiest section is between Boston Medical Center and Central Square. Going outbound (towards Harvard) many passengers get off at Central to transfer to the Red Line or other buses, inbound (towards Dudley), many passengers get off at Huntington Avenue and the Orange Line to make transfers. So here's a relatively frequent scenario:

The black lines show the actual headways. The red
shows what could be accomplished by short-turning
one of the bunched buses at Central Square.
An outbound 1 bus gets slightly off headway, encounters heavy crowds, is filled up, and runs a few minutes behind schedule. Meanwhile, the bus behind encounters fewer passengers, spends less dwell time at stops, and catches the first bus. The first bus may have 60 passengers on board and the second 30. The buses remain full past MIT and pull in together to the stop at Central Square, where two thirds of the passengers disembark (and few get on: it's faster to the the Red Line to Harvard or beyond). So now, the first bus has 20 passengers on board, and the second 10. In the mean time, since the first bus is behind schedule, there is now a 20 minute service gap: the first bus should have looped through Harvard by now, and if the buses proceed as a pair, the first bus will pull right through the loop and head out late and with a heavy load, and even if the second bus has a few minutes of recovery, it will quickly catch the first, and the process will repeat inbound.

You won't be shocked by this, but I went to Nextbus, pulled up the map for the 1 bus, and at 10:15 p.m. on a weeknight, found this exact scenario. See the map to the right. The first bus has gotten bogged down with heavy loads, so there is a 22 minute gap in front of it, while there is another bus right behind. The bus in front should be going inbound at Central right now, but instead both will continue to Harvard, loop around, and start the route bunched: the second bus will lay over for about three minutes and, most likely, after passing several vacant stops, be right on the tail of the first.

This is what the 1 bus route should look like
without any bunching. This is somewhat rare.
And the loop is a particular problem since there is not time or space there for the route to have recovery time, so if a pair of buses enters bunched, they are likely to leave bunched as well. Instead of having proper recovery time at each end, only Dudley serves to even out headways. So bunches are much more likely on the inbound (Harvard-Dudley) having occurred going outbound. And given the traffic, passenger volume and number of lights on this route, bus bunching is likely.

But what if, magically, that bus could be going inbound? Well, it could, and it wouldn't be magic. It would be a short turn. If a dispatcher were paying special attention to the route, the operators could consolidate all passengers on to one bus in Central Square. At this point, the empty bus could loop around and resume the trip inbound from Central (even waiting in the layover area for a minute or two if need be to maintain even headways), where the bulk of the passengers will be waiting. The bus with passengers will continue to Harvard. On the subsequent trip, every passenger's experience will be improved. Anyone waiting for a bus inbound from Central will have service 10 minutes earlier—on a proper headway. And passengers between Harvard and Central will have a bus show up when it would have, except instead of quickly filling up as it reaches stops which have had no service for 22 minutes and subsequently slowing down, it will operate as scheduled.
Note that one bus is catching the other. This is the start
of the bunch. 10:09 PM. It's not too late to short turn!

I watched the route for a while longer, and as predicted, the pair of buses looped through Harvard together, and then traversed the entire inbound route back-to-back, meaning that everyone there waited ten extra minutes, only to have two buses show up together. Every inbound passenger experienced the wonders of a 22 minute headway when the route is scheduled for 12. However, with one dispatch call and a transfer of a few passengers in Central, the headways could have been normalized, and the route could have been kept in order. An issue which was apparent at 10:09 (see the screen capture to the right) could have been fixed at 10:15; instead it lasted until nearly 11:00 (see below):

Now, is this easy? Hell, no, it's not easy. First of all, the drivers have to know that it might happen. Then, they have to be able to clearly communicate it to the passengers. (If you focused on a couple of routes, you could have Frank Ogelsby, Jr. record some nice announcements. Imagine that deep baritone saying "In order to maintain even schedules, this bus is being taken out of service. Please exit here and board the next bus directly behind." Oh, and of course, "we apologize for any inconvenience this may have caused.") You'd have to be damn sure that there was another bus behind and its driver was instructed to pick up the waiting passengers. And a thank you Tweet (@MBTA: Thank you to the passengers of the 1 bus who switched buses so we could fill a service gap at Central) would be in order.

Would it be perfect? No. Sometimes you'd have an issue with a passenger who didn't want to get kicked off the bus. If a bus had a disabled passenger on board, the driver could veto the short turn based on that fact, since the time and effort to raise and lower the lifts would eat in to the time saved by the turn. But most of the time, if executed well, the short turn would save time, money, and create better service for most every rider.

39. The 39 bus is similar. It is heavily used, and it bunches frequently. It also has its heaviest loads in the middle: the stretch between Back Bay Station and Copley is mostly a deadhead move, the bus only really fills up in the Longwood area, and the bus is mostly of empty of passengers along South Street from the Monument in JP to Forest Hills. So at either of these locations, a similar procedure could take place. If two buses were bunched going inbound, the first could drop off in Copley, take a right on to Clarendon, a right on to Saint James and begin the outbound route, rather than looping in to Back Bay and then out again to backtrack to Berkeley before beginning the route. Back Bay is necessary as a layover location when buses are on schedule, but there's no reason to have a bus go through a convoluted loop when it could be short turned and fill a gap in service.

At the other end, two bunched buses could consolidate passengers on Centre Street in Jamaica Plain, at which point one could loop around the Monument (already the layover point for the 41) and begin a trip inbound, while the other would serve the rest of the route to Forest Hills.

So those are my two bus routes that could be short-turned and unbunched. Combined, they carry 28,000 passengers per day: the busiest routes in the system. I would propose a pilot study where the T figured out when these routes are most frequently bunched (they have these data) and then assign a dispatcher to watch only these two routes during these times and, when necessary, short-turn a bus to maintain headways, along with some driver training to ensure proper customer service and expedient routing. It could also record messages, put up some signs, and make sure to have some positive outreach to passengers. This could be done for a period of time, and the results analyzed to see the effect of actively dispatching such routes. If it were deemed a success—if there were fewer bunches and service gaps (data could show this)—the program could be expanded, and perhaps automated: any time buses were detected as being bunched, a dispatcher could be notified, and then make a decision on whether it would be appropriate to short-turn the bus, or not.

The passengers—well, we'd certainly appreciate it, too.

The art and science of a short turn

This post has been a long time coming. A while back I asked people on Twitter if they would be interested in a post about bus bunching and short turns (answer: a resounding yes) and have been stewing on it for a while. I've gotten some feedback that this post is too long, so if you don't care (and it's quite possible that you don't) feel free to skip and read something else. Thanks to my coworkers for looking this over and giving feedback, and the bus drivers on the service who executed the short turn.

A bit of background: in my day job, I work for the Charles River TMA. One of the programs we manage is the EZRide shuttle: a small, last-mile commuter shuttle between North Station (major transit node) and Kendall Square (major employment center). The service has been around since 2002, is mostly funded by local employers and property managers, and sort of serves as another branch of the CT buses, connecting North Station, Lechmere and Kendall. We carry about 2500 passengers per day, and are near or at capacity at peak hours (7:45 to 9:00 AM, 4:15 to 5:30 PM). Most of our ridership is comprised of Commuter Rail riders who work in Kendall. The shuttle is free to corporate members and open for a cash fare to the public.

For the purpose of this blog, I am italicizing certain transity jargon and defining them at the end of the article. Our organization contracts the route to a private operator, and we both have dispatch duties. As it breaks down, they mainly deal with driver issues (broken down buses, drivers needing time off the bus, work schedules) and we keep an eye on passenger issues (loading, bunching, headways).

Our route sometimes allows us short turns, especially when there's bad traffic, but that successfully implementing a short turn takes a lot of know-how, and a bit of magic and luck. Some short turns are relatively easy: two buses are running back-to-back, the first bus as 33 passengers and the second bus has two. (This sort of bus bunching—here's the best resource on that from WBEZ—is all too frequent on busy routes, even when buses run at a scheduled, even headway.) If we can empty the second bus on to the first, we can turn the first bus back to fill a gap elsewhere on the route. This only works if there is a need precipitated by traffic, but that is often the case.

Since many people have asked (okay, maybe a couple people) for a description of a short turn, here is one, with way too many words, and a bunch of maps, too. A follow-on post talks about locations where the MBTA could implement short-turns.


The Route

A short turn doesn't just happen. It comes about from a unique set of circumstances, deep knowledge of the route, traffic, passenger loads, the weather, an innate, built-up sense of what the route looks like and how it will be affected by traffic and loading in to the future. Sure, there's some luck thrown in, but most of that is self-made: a well-executed short turn should be more science than art—it just feels like luck when it works. (And it doesn't always work; rule number one, before you even consider a short turn, is to try to at least not make things worse.) I'll describe a recent short turn success, and the elements that go in to it. The whole of the operation, from diagnosis of the problem to the successful implementation of the turn, took about 12 minutes—likely shorter than it will take you to read this blog post.

We have separate morning and evening routes, due to passenger loading (our reverse-peak carries MIT students) and one-way streets. The route map can be found here, and our route in Nextbus's interface here. The route requires several routes and jogs, mostly due to one-way streets, and it's prone to traffic, especially during construction. Our evening route can be roughly divided in to four segments, each of which takes about 15 minutes, with 16 minutes of recovery time as follows:
Cambridgeport to Kendall Square (moderate commuter ridership, minimal traffic delays)
Kendall Square to North Station (heavy commuter ridership, moderate to heavy traffic delays)
[12 minutes of schedule recovery time (necessary due to traffic)]
North Station to Kendall Square (minimal commuter ridership, moderate traffic delays, although heavy recently)
Kendall Square to Cambridge (moderate student ridership, minimal to moderate traffic delays)
[4 minutes of schedule recovery time at Cambridgeport]

The Situation

On Thursday, April 9, we had some operational issues. Due to traffic signal timing problems, O'Brien highway backed up, and we experienced a 10 to 12 minute delay on our outbound route (this section carries very few passengers at this time of day, but it is necessary to get our buses from the terminal back to the start of the route). On a nice day, we might have some buses operating empty outbound through Kendall Square, but with cold rain on April 9, we had no buses which were empty and could be rerouted, so we couldn't deadhead a bus to the terminal, or an intermediate part of the route.

The scenario was to the point where we had a 15 minute service gap. This is not good for a few reasons. First, this is double our scheduled headway is 8 minutes, so this was nearly double our schedule, even if it means that waits will only be a few minutes longer. But the issues would cascade: the first bus to pick up during this gap would fill up well before the end of the route, meaning the headway for later stops would be longer and would wind up being based on the headway of the second bus, so it would wind up being more in the 18 to 20 minute range.

And then: the bus that was supposed to run called in with a mechanical failure. All of the sudden, 7 of our 9 buses were on the outbound route, and we were facing a 20-24 minute service gap. In other words, we were screwed. Here's the setup:

The arrows show the inbound route, and the red dots show the major passenger generators at this time of day (peak rush hour); as you can see that there are no inbound buses between the west end of the route and the eastern terminal (just off of the map) except for bus 9901, which is most of the way there. (Ignore the times "late"; we'd already had some delays to this point.) Bus 711, shown in gray, is broken down. And the driver of bus 708, at this point, got off his bus to try to diagnose the issue of 708, and due to radio traffic we were unable to tell him to get on his [goddamn] bus and drive the [goddamn] route.

So now we had a problem. 706 caught 708. We needed a bus to run the route, but expected it to fill up before it could board all the waiting passengers, especially at the three red dots. It also coincided with the peak loading time for our route, when even under normal operations buses can load to capacity and leave riders behind. We could send a double draft to run the route, but then the second bus would wind up empty behind the first bus as it boarded passengers (most of our route is too narrow to safely pass) meaning that the passengers later in the route would have a longer wait. While I was yelling at no one in particular about 708 (in our office, using curse words) my boss (who has been watching this route for more than a decade: that's institutional memory) mentioned that we could deadhead 706. What a splendid idea—as my ire grew with 708 for attempting to fix a broken down bus and not just covering the route I hadn't noticed this possibility. (To be fair, the driver of bus 708 probably didn't realize the situation on the rest of the route.)


The Operation, or, the Rules of the Short Turn

Rule #1 of the short turn: Don't Make Things Worse

The first question to ask in a short turn is: will this actually make much of a difference, and might it make things worse? If you are going to move heaven and earth to get a bus somewhere 90 seconds earlier, it's much easier to just have buses run the regular route. Unless you can solve a loading issue and a headway issue together, it's rarely worth doing. (A service gap in a non-peak direction affects many fewer passengers than in the peak.) The second question is: will this short turn now cause more problems later? If the answer is yes (and quite often it is), you have to weigh how severe of a problem it will be, and when it will occur. Can you solve an inbound issue at 5:15 that creates an outbound service gap at 6:15? Fine, better to improve the ride for 50 riders and inconvenience a handful at a much less busy time. If you can get two people off of the second of a bunched pair and on to the first, turn the empty bus and cut the wait time for two dozen, totally worth it. But if you're trading off a delay for three people now versus a delay for five people later, it's not worth doing. 

In this scenario, we were not going to inconvenience anyone, really, and improve service for a lot of people (and get buses better spaced in to the future). It was a no-brainer.

Rule #2 of the short turn: Know Your Route.

If you're running a short turn, you need to know your route. You need to know where a driver can go around a block easily, or where they might get stuck in traffic (or worse: a tight corner not suited to a 40 foot bus, a frequent problem in Boston). Before you can do this kind of active dispatching, you have to know where you can safely and expediently turn a vehicle. It helps to have twenty-plus years of dispatching in the other two members of my office (I'm the new guy): they've been through everything. Construction detours, full road closures (the Craigie Bridge reconstruction), never-ending blizzards (okay, that was this year) and the like.

Due to the one-way nature of Kendall Square, the route does have a bizarre loop built in, which takes a couple of minutes to traverse but accesses a major stop. So one idea would be to deadhead bus 706 and have him run out of service (and preferably off-route down Main Street to Ames: nothing makes passengers angrier than seeing an empty bus drive by without stopping) and pick up at the last red dot on Broadway. If he got there expediently, he'd be able to at least pick up at that stop—and ensuing stops—and mitigate the service gap there, and take on the passenger load the first bus, 708, would not be able to pick up.

Rule #3 of the short turn: Be Invisible.

To passengers, at least. The best short turn is one where the deadheaded bus doesn't pass any passengers waiting, where no passengers are asked to leave the vehicle, and where, except for the driver and the dispatcher, no one knows. This could also be phrased as "don't piss off the riders" which is always a good policy: sending an empty bus past waiting passengers is a recipe for angry calls and emails. Generally, we operate under a policy of transparency with riders (we will suggest alternate transit means during especially bad traffic, for instance—it's beyond our control but our goal is for our passengers to get where they're going, not to boost our ridership), but we don't feel the need to describe every piece of our operation. In the case of a short turn, we might send out a Tweet such as "Service gap inbound due to residual traffic delays and disabled bus. We will attempt to redirect service to fill this gap" usually suffice.

Rule #4: Know your Drivers

Now at this point it is worth pointing out that that you really need to know your drivers when juggling buses in this manner. Some of the drivers on our route could dispatch themselves: they have an innate idea of where every other driver is on the route, what their scheduled times are, and what their likely traffic and passenger load impacts will be. (Another recent night, two long-serving drivers basically rerouted each other and other buses, on the fly, to avoid traffic and fill route gaps far better than I could have even while staring a map of the bus GPS locations.) Other drivers are newer to the route and may not know the vagaries of Cambridge's off-route street grid, and need a lot more guidance across the route. In this case, the driver of 708 is somewhat newer and knows the route fine, but harder to manage: we were happy that his only instructions were to run the regular route. The driver of 706 is one of our best and has been driving the route for a while; a simple instruction like "deadhead to Main Street, left on Ames, first pickup on Broadway" would be all that he'd need.

So that's what we did. Bus 708 would run the regular route making all stops, and would likely be full at Kendall Square. (The buses we currently run are 35 foot buses with 32 seats and a stated crush load of 45, although more passengers have been known to cram aboard.) There was no point holding 706—we had another outbound bus behind him—so we sent him to do the pick-ups beyond Kendall, but to take a direct route there, leapfrogging ahead of 708 and shortening the wait at the subsequent stops (and we expected him to fill up at those stops). 708 would then run by those stops a couple minutes after 706, so would have fewer passengers to pick up. 

Rule #5: Pay Attention.

But the operation isn't over until the buses are back on the regular route, drivers know future departure times, and they have recovery built in to get back to normal. So far, everything was going according to plan, but you have to pay attention to a short turn until it's on its way to a logical conclusion. 706 had made good time on Brookline Street and had chosen an appropriate, off-route path for his deadhead; again, had this bus passed a group of long-waiting passengers, they'd go from irked to irate. 708 was serving some moderate-ridership stops, and headed towards Technology Square, where he'd take on many more passengers. 

#Protip: if two buses are coming together, take the second one. It's unlikely to be any slower (it might actually pass the first bus) and you're more likely to get a seat.

Anyway, the plan was working, rather swimmingly. And then: nirvana. See how, above, bus 707 is catching up to bus 709? While this is not a busy part of our route, but on a rainy day, there are some passengers who will take a circuitous bus ride to Kendall rather than make the walk. So while bus 709 was stopping for a rider here an there, 707 wasn't, and he radioed in that he was behind bus 707, and was empty. Bingo. We were worried 708, upon reaching Kendall Square, would be too full for the boardings there. But 707 could conceivably balance the load between three buses as long he was slotted in before 708 reached Kendall. Each of the main passenger nodes would get its own bus, balancing the load well. If it worked. It was worth a try.

But remember: you have to know your drivers. 712 is a driver who had recently bid on to our route, and had had some issues with the route (not entirely his fault: our route flips based on the time of day—since we serve students and commuters in separate directions—and can be confusing for both riders and drivers to learn, although once familiar, it works quite well) and certainly didn't know his way around Cambridge. In other words, if he'd been in 706 a few minutes earlier, it's doubtful we would have sent him on the deadhead in the same way we did 706.

Somehow this worked.
But we could coach him through it. 706 and 708 had their charges, and the radio channel was clear. So the call went out. "707: take a left on Broadway, then proceed straight down Main to Third Street. Make a right turn there, and make your first pick-up at Kendall Square." We'd have to watch him like a hawk and keep in radio contact: if he missed the turn there, at best we'd have to coach him on to Memorial Drive, and on to the outbound route (a portion of our route uses Memorial Drive, and our drivers have never missed the turn and gotten stuck under the Mass Ave overpass). At worst, we'd lose him across the Longfellow for half an hour. (Don't laugh. This has happened.) The short turn can be dangerous.

And it worked! 707 made the short turn in to Kendall and instead of following 709 on the outbound switched to the inbound. Astonishingly, we had evenly spaced the buses with about 3 minutes between each, which is particularly impressive since that meant that 706 was now 6 minutes—nearly a full headway‚ ahead of 708, who had left the route terminal behind him! And both 706 and 708 were nearly full, so bringing in 707 kept bus 708 from reaching Kendall, filling up there, and then reaching the next stops later, with more passengers to pick up, filling further, and perhaps leaving passengers behind. Much of the credit goes to the drivers, who let us know their situations (when they were empty and bunched) and were willing to jigger their routes in order to balance the load. The fact that such reroutings are not infrequent means that they're used to being asked to do so, and that they execute the maneuver well.

Once the buses had all made their way on route, we actually had well-spaced buses. In fact, 706 and 708 were a full headway apart at this point: had we not deadheaded and short-turned they'd both be where 708 was, and we'd have cascading issues as they both ran into and then out of the terminal late. (Often, a headway issue at 6 PM can be caused by a traffic jam at 3:30.) But the pieces of the puzzle had fallen in to place, and the short turn had been executed, successfully. 

This is pretty much what our map should look like in normal service. (Well, except that the buses were way off their originally scheduled runs, but if I look at the map and every bus is 20 minutes late, that means that we have even headways and just had some issue earlier on.)

As my boss said, it was ballet. It was all over in about 12 minutes. But the best part? We had the buses in numerical order: 706, 707 and 708. Boom.


The Aftermath

Why "art and science (but mostly art)"? It's often suggested that computers could do this better than people, and why do transit agencies employ dispatchers, anyway, since an algorithm would do a better job? But that assumption is flawed for several reasons. First of all, unless an algorithm has nearly perfect ridership data, someone familiar with the route will have a better idea of where and when stops have heavy demand. Second, an algorithm would have to be able to not only know that a deadhead route will have less traffic at a given time than the normal route, but also communicate that route to the driver (and, frankly, I don't find Waze and its ilk that useful at the block scale). And the algorithm would have to know which buses were full and empty: passenger counters are not perfect, but a driver can pretty quickly and easily respond to a radio call of "do you have any passengers?"

But the fundamental issue is that this type of service is dealing with people, both drivers and passengers. It's pretty easy for a person—with some knowledge of the route—to balance out which stops to serve, and in what order, and what stops to prioritize. Maybe you're a bit less concerned with Kendall Square because it has a shelter, so a minute or two longer there isn't a problem. Maybe you know that given the weather one stop is more likely to be used than another because it has an overhand or an alcove for people to stand at. Maybe you know one driver is able to navigate the route faster than another (we have one of these: he drives safely and smoothly, but knows the route so well he regularly covers it faster than any other driver), while another is slower. Maybe one bus is balky and you don't want to push it lest it break down.

Certainly you don't want to deadhead an empty bus past a full bus shelter, or incur the wrath of customers who—even if you are doing it for the benefit of the service—would be understandably upset. And it's also important to know your drivers, know what they are capable of, and talk them through what they need to do. Because despite all the talk of autonomous vehicles and hyperloops, right now and for quite some time to come, buses are driven by people and carry people, and despite various limitations, there are certain things where the Turing Test is still yet to be achieved.

A subsequent post will discuss routes where the MBTA could potentially use short turns to mitigate the effects of bunched buses.


Deadhead: run an empty bus without stops, and possibly on a more direct route.
Headway: the time between buses.
Double draft: two vehicles running together; more of a train term coopted here.

Saturday, April 11, 2015

How much money could All Door Boarding save?

This is sort of a post-live blog from Transportation Camp NE. One of the first sessions was regarding all door boarding on the MBTA. There are a lot of ins and outs—notably, that you have to account for all scenarios where people could access the system, for example potentially without paying a fare (Silver Line airport) or having proof thereof (boarded with a friend who paid and parted ways)—but it was a good discussion, and something that is moving forwards, but needs to move faster. I pointed out that the discussion needs to not be pushed by the small minority who complains (loudly) about fare evasion, or really by fare evasion at all, but by vehicle speed and efficiency, since 95% or more of passengers already pay their fare: we need to improve service for the vast majority.

Often, when we talk about all door boarding, we talk about the real and potential time savings. Muni, in San Francisco, started experimenting with all door boarding, and it turned out it worked really well, and they went system-wide, and it has saved passengers time. According to their final report, it saves 1.5 seconds per passenger boarding or alighting, and speeds overall vehicle speed by 2%. 1.5 seconds does not seem like a large number, but it begins to get a lot bigger when aggregated over a large number of passengers.

SF Muni and the MBTA have a similar number of surface passengers: about 500,000. (The T has about 400,000 bus passengers and another 100,000 or so surface boardings of light rail; looking at only surface lines, the T and Muni are actually quite similar in terms of size.) So, if we can save 1.5 seconds per person—we'll look only at boardings, since many trips either end at a terminal station where all doors are used or are surface Green Line boardings that end in a tunnel—we wind up with 750,000 seconds saved per day. This is, rounded down a bit, 200 hours saved. The cost of operating an MBTA bus is about $163 per hour, and for a light rail vehicle $250 per hour. Let's assume that half of that is direct operating cost: operator wages and such. Assuming the lower bound, it would save $16,000 per day. Even if there were no savings on non-weekdays, in 250 weekdays it would equate to operational savings of $4 million

Savings add up, quick.

Let's look at it a different way. A full, two-car Green Line train in the morning carries approximately 300 passengers. On the B or the D lines, the surface portion of the route takes 32 to 34 minutes to run at peak rush hour (according to the T's scheduled time). Saving 1.5 seconds on each of these boardings, would equate to 450 seconds, or 7.5 minutes: more than a 20% savings for the above ground route. With the addition of signal priority on the B line, you could be looking at speeding the route by 30% or more—a game changer for one of the slowest—and most heavily-used—surface lines.

The transit planners will say "well, these savings will probably just be added in to headway recovery time." First of all, if you actually do realize a 7 minute saving, you're talking about an entire rush hour headway, so I doubt it will all disappear, unless you are going to be lining up multiple vehicles at rush hour. But second of all, if these wind up making headway recovery times much more even, that's great. That means you'll have the same capacity without having to dispatch a train as soon as it arrives, but rather on even headways. This is likely to reduce the number of vehicles that wind up bunching, overloading and slowing down.

But let's run with the $4 million figure. There are, on buses and the Green Line, probably about 1500 doors that would need car readers. If a pole-mounted reader costs $4000, the system could be paid for in a year and a half. Or if the system were assumed to last five years, you'd have $20 million to put towards the cost of the readers ($6 million) and additional enforcement ($12 million, or $2.4 million per year).

Oh, and customers? They'd get a faster ride. It's a win-win, for everyone. Except the few curmudgeons who are less concerned with how the vehicles run, and more about the anecdote about the person they once saw jump a fare gate.

Wednesday, April 1, 2015

Downtown Boston is Busmageddon? Really?!

Update: A shortened far less ad hominem version of this has been published in Commonwealth Magazine.

Every so often an article comes along which is so inane, so poorly researched and so utterly stupid that it requires a line-by-line refuting.

The article in question, which has a dateline of March 31 so I'm assuming it's not an April Fools joke, is:
End downtown Boston’s busmageddon Add reworking bus routes to the MBTA’s to-do list
Oh boy.

The first four paragraphs go on about how people are taking public transit in Boston. Fine. Then you get to paragraph 5:
We need a comprehensive policy regarding usage of the public way. 
Good! We agree. We do need a comprehensive policy regarding usage of the public way. Right now, approximately 75% of the roadways in Downtown Boston are dedicated to automobiles. Another 20% are sidewalks, and 5% are bike lanes. Yet the number of cars is decreasing (to quote the author two paragraphs earlier), and the majority of people coming to Boston don't use cars. So why do cars (as usual) get the vast majority of space? Why should they get all the real estate if they only account for a minority of travelers? Who knows.
Loading must be done during limited hours, as is the case in other great cities.
Loading? Fine. That's a halfway-decent point. Care to elaborate? (Apparently not.)
To keep the city from devolving into perpetual gridlock, we also must address tour buses and MBTA buses downtown.
Boston has no through bus routes through downtown, the only city in the country to do so. Perpetual gridlock? How much of the gridlock downtown is caused by buses at Haymarket (in their own terminal, mind you), the Franklin-Federal loop, the Silver Line and a few other sundry routes, as opposed to, say, tens of thousands of cars trying to ply narrow streets downtown? Tour buses? Sure, get rid of those space-hogging menaces. But getting rid of a few MBTA buses? Please.

And what of these other great cities? What do they have in common? London? Bus lanes. New York City? Bus lanes. Minneapolis? Double bus lanes. Boston? Well, we have the Silver Line, but it barely has bus lanes downtown.
Let’s get the buses off of our streets so that pedestrians and bicyclists can be safe.
Red herring! Red herring! Red mfing herring! T Buses account for, oh, maybe 2% of traffic downtown. Maybe. Probably less. Certainly far less than any other city in America. Take a look at Bostonography's great bus speed map (a screen capture to the right). Notice that there is actually a gap in Downtown Boston with no bus service. Compared to nearly any other city in the country, Boston has less bus service in its downtown. Other top bicycling cities like Minneapolis, Seattle, San Francisco and Portland have many more buses, yet no one is demanding that buses be pushed to the outskirts there.

Yet buses are menace to pedestrians and bicyclists? Should we consider doing something about the other 95% the traffic downtown? The cars? Or are pedestrians and cyclists somehow immune to them?
As Doug Most reminded us in The Race Underground, Boston constructed the first subway tunnel in the late 1890s to get trolleys off the street; we can certainly do likewise today by making good on the commitment to a tunnel connecting South Station with the Silver Line spur that heads to Dudley Square.
Oh, good lord. Yes, we could spend $2 billion to build the Silver Line Phase III tunnel. Somehow this would solve all of our transportation problems. Except for the buses going to Haymarket, South Station and all of the express buses. It wouldn't really get any cars off the street (although by his logic, cars on the street aren't the problem). It would create a low-capacity, slow route that could be replicated for 1/100th of the cost with signal priority and bus lanes. But that might impact cars and their drivers dense enough to think the best way to Downtown Boston is to drive.
There is also no reason why people wanting to go to Salem should have an express bus waiting for them around the corner from Macy’s …
Most people going to Salem don't wait by Macy's: they wait at the Haymarket bus station. (Also, if you're actually from Boston, it's Jordan Marsh. But I digress.) It's not perfect, but it's covered, and the buses pull in to a busway to load and discharge passengers. But so what if they do? Downtown Crossing is right in the center of the city. If we make people from Salem walk ten minutes, or squeeze on to an already-over capacity subway train, they're more likely to say "the hell with it" and drive. Do cars cause congestion? Or just the 16 buses per day that run from Salem to Downtown Crossing?
… nor should city street patterns necessitate that a bus make a left turn from a right lane to meander through downtown streets to get to the Mass Pike.
The 500-series buses do load on narrow streets and have to reach the Mass Pike. Why? Because they are basically the replacement for the other two tracks of the Boston and Albany railroad. When the tracks were paved over for the Turnpike, the 500-series buses replaced local service there. There were proposals in the '40s to run service similar to the Highland Branch from Park Street, out the Tremont Street portal, on to the tracks parallel to the current Worcester Line, and out to Allston, Brighton and Newton (huge file here). Instead, we had got the Turnpike, which express bus service, which is express until it sits in Turnpike traffic. If you hadn't built the city for cars, you wouldn't have to worry about the buses; the streetcars could be underground in that aforementioned tunnel.
Large buses making wide turns on narrow downtown streets, even more narrow because of mounds of snow, clog the streets and imperil the safety of the public. 
Large buses clog the streets? What about parked cars? What about moving cars in traffic? How about we eliminate downtown on-street parking and give the buses their own lanes, and make sure the mounds of snow are removed from them. And do only the buses imperil public safety? No pedestrian has ever been killed by a car, right?
We should eliminate bus lines which make no sense and relocate the terminus of lines now heading downtown to South Station and North Station …
We have an intercity bus terminal at South Station. It's at capacity. There's no way to add T buses in to it. And it's a five minute walking transfer to the already-over capacity Red Line.  The current routes that could conceivably go to South Station aren't perfect, but they seem to work. Maybe we should create a network of downtown bus lanes instead? Cyclists and pedestrians would know where the buses would be, and it would help buses move through downtown more quickly.

And North Station? That's why we have the Haymarket bus station. It has room for buses and easy connections to the Orange and Green lines. Perhaps when the Government Center Garage is rebuilt, it will include a better bus terminal and connections, and bus lanes across the bridge to rebuilt bridge to Charlestown.
… where there is access to underground transit, commuter rail and the interstate highway system.
Yes, there is access to underground transit. That's all well and good. Except that underground transit is growing faster than other parts of the system, while struggling with decades-old equipment and overcrowding. Most downtown buses operate like commuter rail: they go from the suburbs to the city. There's little need for passengers to transfer to commuter rail, rather they want to transfer to their place of work. Instead of dropping people at the outskirts of downtown, we should have more central bus routes that balance operational efficiency with getting people where they want to go. Give as many people a one-seat ride and a comfortable place to wait, and they'll be more likely to ride.
Even as we eagerly await the Red Sox return to Fenway Park, and the melting of the last mounds of snow (most likely in that order), we should be thinking – and planning – ahead.
If you really want to encourage safer streets, getting rid of transit is certainly not the way to go. Planning ahead will certainly be important, but let's plan the right way. The right way might be a congestion charge, to get cars off the streets at peak times. The right way might be to build bus lanes so that bus riders have seamless trips through downtown to their destinations. The right way might be to require tour buses, an actual menace to pedestrians and cyclists which provide no actual public good, to stick to certain streets, routes and times.

Or the right way may be to raise the goddamn parking tax. Right now, Boston has one of the lower parking taxes around. Because parking is very much constrained, it is not subject to the whims of supply and demand: a daily tax on parking spaces would likely not even affect the consumer price much, but move some of the profit from the property owners to the city. Given the negative externalities of cars on city streets, and the fact that most people utilizing parking spaces are from out of town, the city should raise taxes and use the money to improve public transportation, perhaps starting with, that's right, buses.

So the right way is not to demonize public transit and couch it in the guise of pedestrian and bicycle safety is disingenuous at best. Ignoring the fact that nearly all traffic downtown is made up of cars driving on subsidized roadways and offering debunked solutions is a farce. Note the red X on the map to the right. It shows the location of the author's office in relation to the 448/449/459 and 500-series bus routes in Boston. What are the chances he's just rubbed the wrong way by seeing a bunch of buses outside of his office? You know, buses that make it really convenient for people to get there?

Let's build better bus facilities. Lincoln Street and the Surface Artery which all the 500-series routes follow have plenty of room for a bus lane (Lincoln Street has two lanes of traffic and two of parking). Federal has parking on both sides. Why not take some of that space which is making the streets narrow and dangerous and use it for buses? It might make it a little less convenient for Mr. DiCara to drive there. That's probably his real beef.

And Commonwealth Magazine should be on the hook, both for not fact-checking this article, and for letting someone with no actual expertise in the industry write it in the first place. Just because he saw a lot of buses at Lincoln and Summer one morning doesn't mean that they're the problem. I wonder how he gets to work, anyway?