NextBus accuracy slips, “ghost buses” explained
Photo from {Guerrilla Futures | Jason Tester}.
WMATA released NextBus accuracy statistics last week, and frequent users will not be surprised to find out that accuracy is not where it could be.
NextBus only has predictions for 78% of buses, far below the 92% accuracy target. The buses themselves are also not keeping to schedules particularly well, being “on time” only about 75% of the time even with a generous on time standard of up to 2 minutes early (which buses exceed almost 7% of the time) and 7 minutes late (which they exceed 18% of the time).
Bus manager Jack Requa provided some explanation for the “ghost buses” that riders widely reported: if a bus stands still for 2 minutes, the NextBus system stops showing that bus at all. It also removes the bus if it deviates more than 160 meters from the typical route, meaning that any bus reroutes generally result in disappearing buses.
The Examiner’s Kytja Weir noted that this accuracy is lower than the 80% present when Metro “paused” the program for two years. That doesn’t mean Metro should take NextBus down again (and they don’t plan to), but does suggest some folly in taking it down in the first place, or keeping it under wraps until it was extremely accurate.
Still, when NextBus does work, it is very useful. When predictions do exist, they are usually correct (but not always), and make it possible to leave home or work just in time to catch a bus. Weir quotes Arlington Board member Chris Zimmerman saying, “NextBus has been one of the best things … It’s greatly improved the quality of my life. … That said, it has to work with a fair amount of accuracy.”
Overall, all riders are better off having an imperfect NextBus than no NextBus at all. However, the accuracy needs to improve. It would help for WMATA to detail its specific plans for what can be improved and at what cost.
Chart from WMATA.
million uses [there were] only 148 complaints. The important thing is, there are very few complaints, and customers are happy.”
But many customers don’t complain because it’s very difficult to complain. The online complaint form is very complex, and there aren’t easy links to give feedback from the NextBus interface on the Web or on the phone. If Metro made it easier to complain, they would have more information about problems, but under the “customers are happy because there are few complaints” standard, it would make things seem worse. I hope that’s not deterring the IT staff from making it easier to report problems.
It’s terrific that Metro is tracking the accuracy for each bus garage and division, giving managers inside the bus system direct feedback about how well their groups are doing. The “dashboard” statistics we see do not reveal the causes of this inaccuracy, however. Are operators not signing on? Are the transponders breaking down? It would be helpful to see what percentage of the inaccuracies creep in at each stage. Zimmerman asked for this as well at the meeting. It looks like the dashboard listed on the Board presentation has the bottom cut off, so perhaps this information is on the full charts.
Accuracy seems to have slipped since January. The previous presentation showed log-on performance of 89.46% for the week ending January 23, 2010. Showing overall predictability instead of log-on performance is a better number, though it would be nice to show both. Bus performance also dropped, from almost 80% in that January week to 75% today.
Metro staff said that they are working on the problems, but gave few details beyond assurances that they were “doing everything that they can” and that “a lot of manpower and resources is needed.” It’d be helpful to hear a roadmap for what Metro staff or the NextBus company itself is going to do to improve things. Ultimately, though, the proof will be in the numbers.