Transit
Fewer "ghost buses" haunt NextBus
Most of us only see ghosts when people dress in costume on Halloween, but bus riders deal with "ghost buses" on a regular basis. These are not spirits haunting your ride to work, but Metrobuses that mysteriously disappear, or never appear, on the NextBus real-time prediction system. The system now has fewer errors, but riders still encounter problems.
Photo by Stevesworldofphotos on Flickr.
Ben Ball, a representative on WMATA's Riders' Advisory Council (RAC), offered an example of the "ghost bus" problem:
Every day at around 4:40 or so, I check the Metro website to see when the next N2 or N4 bus will approach Ward Circle heading eastbound to Farragut Square. There's usually an N2 in around 8 minutes, and an N4 at around 10 minutes. This week, both are displaying 24 minutes, and there is no bus displayed on the arrivals map. But that doesn't mean that there's no bus.
In fact, when I went toward the Red Line on Monday based on the fact that the next N2 wasn't supposed to come for 24 minutes, an N2 streaked right past me as I was walking up Nebraska Avenue. And then there was another one at TenleytownWhen a bus disappears from the system, the most likely culprits are a lost GPS signal, a bus logging off the system, heavy traffic, a detour, or a bus breakdown, said WMATA chief spokesman Dan Stessel. A bus will disappear from the NextBus system if it stands still for more than 2 minutes or deviates too far from the assigned route.— two ghost buses in a row.
A bus arriving without ever appearing on NextBus can happen when a driver doesn't log on, equipment fails, or the data feed breaks, Stessel added. This problem has receded to some degree. Before 2011, Stessel said, some 300 buses ran daily without active GPS signals and radios. This year, there are just 40-50 on an average weekday.
WMATA re-launched NextBus in 2009, after discontinuing service in fall 2007 due to accuracy problems. NextBus receives data from GPS locators on the buses and uses them to estimate when a bus will arrive at a given stop. Users can access bus predictions from the WMATA website or through a mobile app.
WMATA uses two metrics to measure NextBus' performance. "Predictability" is how well the system locates each bus and determines when it will reach a stop. This depends on factors Metro is responsible for, such as bus drivers logging on, working equipment and accurate schedules and stop locations. Predictability has improved over the past 2 years, Stessel said. WMATA gave itself a predictability score of 87% in April of this year, up from 85% in April 2011 and 77% in April 2010.
The second metric, "accuracy," depends largely on the NextBus software. A prediction counts as "accurate" if, when the system predicts a bus to arrive within 5 minutes, the bus actually arrives within 3 to 7 minutes. On this metric, NextBus scores above 90%.
What has WMATA done to make the predictions more realiable? Stessel explained that Metro set up an education program and uses performance center monitoring to ensure that bus drivers remember to log into the system and stay on throughout their shift.
Metro has also upgraded onboard radio and communications equipment, and has a project underway to replace existing systems with more modern technology. The newer systems will "poll" buses' GPS locations every 30 seconds or less; the older systems only "poll" every 120 seconds, meaning that buses can travel a fair distance before the NextBus system knows about it.
Still, Stessel said, there is no way to completely resolve prediction issues. "While the new technology will greatly increase reliability and data availability, factors like detours, traffic and weather" will always play a role.
In the meantime, Ball laments that there is no easy-to-use system for reporting bus outages to WMATA. Former RAC chair Dennis Jaffe noted in 2010 that the generic feedback form is complicated and hard to use. There is also no easy way to report NextBus errors from the WMATA bus prediction interface or the mobile apps.
What have your experiences been with NextBus?
Jeremy Barr is a graduate journalism student at the University of Maryland. He previously worked in non-profit communications and has interned in politics on several occasions. In the last year and a half, he has lived in Adams Morgan, Logan Circle and Mount Vernon Square. Email him at jeremy.m.barr@gmail.com.   |
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by drumz on Oct 23, 2012 10:36 am • link • report
by Emily C. on Oct 23, 2012 10:51 am • link • report
for some reason Nextbus always shows the 29G arriving at its annandale stops in the AM at the time of the posted schedule, even when its significantly delayed, but the Nextbus screen at the Pentagon appears to be accurate.
by AWalkerInTheCity on Oct 23, 2012 10:51 am • link • report
by Steve Strauss on Oct 23, 2012 10:53 am • link • report
by MDE on Oct 23, 2012 10:56 am • link • report
Maybe thats the problem, thats how I use the service at a bus stop.
by AWalkerInTheCity on Oct 23, 2012 10:57 am • link • report
My only complaint today is that the predicted times change rapidly, but I don't really see a way to make that better on a road so heavily trafficked as Arlington Blvd--if traffic is moving smoothly, great, but, especially during rush, traffic moves pretty haphazardly down that road.
by Shaun on Oct 23, 2012 10:57 am • link • report
Right. The false positive is a bigger problem for the user than the false negative.
by Alex B. on Oct 23, 2012 11:01 am • link • report
by Matt on Oct 23, 2012 11:03 am • link • report
by Dan H on Oct 23, 2012 11:07 am • link • report
I have to say, it really does seem certain buses are haunted. There is one 3y that never shows up (the 5:30?).
The most helpful part for me is the little map that says where the buses are; if there is a large jam-up the predictions go haywire but you can make up your own mind. I just wish they would provide that in text form rather than the map -- on smartphones you end up scrolling around too much.
by charlie on Oct 23, 2012 11:20 am • link • report
by rdhd on Oct 23, 2012 11:26 am • link • report
I arrive at a stop at 2:27PM. Schedule says the bus is supposed to be there at 2:30PM.
At 2:40PM, the bus hasn't arrived. I say to myself, "Was it early? Did I miss it?" I call NextBus.
NextBus says that the next bus will be there at 3:30PM.
I say to myself, "Damn, I did miss it." Not wanting to stand around for 40 minutes, I walk away from the stop.
I am passed by the bus - the 2:30PM bus was late.
by John Flack on Oct 23, 2012 11:30 am • link • report
Also, why did RideOn choose not to use NextBus? Every time I go to MoCo, this lack of consistency makes it a challenge to effectively use RideOn buses. The app I've seen for RideOn is not that easy to use or accurate.
by Steve on Oct 23, 2012 11:30 am • link • report
by Gray on Oct 23, 2012 12:10 pm • link • report
by Nose Straw on Oct 23, 2012 12:26 pm • link • report
Even if we accept Metro's 87% number as correct and unvarnished, a rider using NextBus on a two-way commute will have a "FAIL" experience more than once a week from this problem alone. Given how many other ways Metro can let bus riders down -- and the problems buses can suffer that are in no way at all Metro's fault -- NextBus simply needs to be a very accurate and reliable part of riders' commutes, not a weekly point-of-failure.
If you compare the NextBus experience to not having NextBus, then the experience on infrequent bus routes has been GREATLY increased. There is, of course, room for improvement. But at the same time, NextBus exists as a supplement to the bus schedule, it does not replace it. Buses are still expected to conform to the schedule, and on-time performance is still measured against the schedule.
Really what WMATA needs to make sure of is that there aren't buses showing up on NextBus that aren't coming - and as far as I have heard this doesn't happen as often as it used to. If NextBus shows no buses coming for a long time, you can always figure out how to make other arrangements. But if you are expecting a bus and wait for it and it doesn't show, that's a bigger problem because you've now wasted your time.
by MLD on Oct 23, 2012 12:50 pm • link • report
by rdhd on Oct 23, 2012 1:05 pm • link • report
by JJJ on Oct 23, 2012 1:10 pm • link • report
I do agree that the non-arriving bus is a much, much bigger deal than the bus that doesn't appear in the system. If a bus looks like it's going to come shortly I'll choose to take a bus; if it never shows, I may have wasted a lot of time if I didn't take another option because of the false NextBus info. Plus, many riders will waste even more time waiting at the stop, wondering if the GPS info was estimating a quicker arrival than happened because of traffic delays, which may then delay other transit options even further.
That said, having NextBus has been a *huge* improvement on not having any information at all. Even when it was in beta back in 2007 it was so much better than not having any idea when a bus might meander along, given that the schedules always seemed to be more suggestions than aspirations.
by Moose on Oct 23, 2012 1:27 pm • link • report
by Bob Jonsen on Oct 23, 2012 1:33 pm • link • report
by Justin..... on Oct 23, 2012 5:06 pm • link • report
I'm glad to see so many people riding the bus. It really is the way to improve and expand public transportation in this area.
(HATE the new verification.)
by Jazzy on Oct 23, 2012 6:04 pm • link • report
I've taken the T in Boston and Nextbus was a god send for me when I went there last year. They have a different AVL system from Metro and that one seems to be better suited. Also, they have a different scheduling system which also might take into account. I know Metro is supposed to be replacing the Orbital AVL with Clever Devices to improve not only operations, but to provide better polling and reliability. LA Metro has the same setup as WMATA and their system seems to have greater reliability and up time than here.
I have noticed that some buses, especially late night, don't quite show up on Nextbus nor WMATA's API. Friday and Saturday late nights are especially a problem. A couple routes, the 7A and 16E have trips that go up to 3am but you don't get predictions after the 1230am trips even though there might be a bus that is logged in. There might be some issue with the accuracy and wholeness of the data being sent to Nextbus. There is this weird anomaly that occurs sometimes on the weekends when you'll get predictions on some weekday trips (mostly on Sundays). I've also seen where two buses show up on the same block assignment with the same prediction times. So, basically, the current AVL system is really making predictions very inaccurate and this is why I always have the schedule as a backup.
by Ken Conaway on Oct 23, 2012 8:08 pm • link • report
Why are there electronic signs only at a few stops throughout the whole system. Why not put them at all stations or even just have a giant LCD screen (Stadium Size) in the bus bays of a station that stops every route and when it is supposed to arrive.
by kk on Oct 23, 2012 8:11 pm • link • report
Agree with most of what you said. I think a solution would be to have an easier way to report NextBus errors so that WMATA can analyze those to see what went wrong. I disagree about the lack of depth on this post.
(HATE the new verification.)
Then click the little box that says "save my name and email address..." and you won't have to verify every time.
@kk
Why are there electronic signs only at a few stops throughout the whole system.
There are plans to install many more signs at bus stops.
by MLD on Oct 24, 2012 8:59 am • link • report
by MDE on Oct 24, 2012 9:38 am • link • report
Just go to www.nextbus.com on a mobile device*, and you get a list of buses that are arriving near your current location, sorted by distance and time.
*This link will force the mobile site to load in a desktop browser if nextbus.com sends you to NextBus's ugly corporate site.
It's far better than any of the other sites or apps that I've seen, and it lists buses from any agency that has a contract with NextBus (DC Circulator, THE Bus, Fairfax CUE, GMU, UMD), as well as many other metro areas. It does one thing, and does it very very well -- no clicking, no typing, just a list of nearby bus arrivals.
by andrew on Oct 24, 2012 10:59 am • link • report
However, it usually only works for the CUE bus. If I look up the 2B/2G MetroBus routes, I only ever receive a "Connection Problem" message. The findametro app is somewhat useful but you have to know the stop ID to use it.
I've used NextBus for the MetroBus 1C it works a little more reliably so it may just be the construction detours at Vienna Metro that are throwing off the 2B/2G.
by Cory on Oct 24, 2012 12:09 pm • link • report
The problem with the 2B/2G may be an issue with the app - not sure if you have an iPhone but the iPhone app often takes a long time to update route/stop changes etc.
Try out the nextbus site on your phone that andrew posted above you - may be of more use if you are close by.
by MLD on Oct 24, 2012 12:39 pm • link • report
Ben Ball's usage of "ghost bus" is unusual. Every time I've heard "ghost bus" it's from someone who is waiting for a bus that NextBus says is coming...then it disappears.
A ghost bus is visible on NextBus, but vanishes before arrival.
A zombie bus isn't on Nextbus, isn't supposed to be alive, but it lurches past you anyway.
by Matt C. on Oct 25, 2012 3:23 pm • link • report
by Steve on Nov 13, 2012 3:32 pm • link • report
by Steve on Nov 13, 2012 3:51 pm • link • report
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