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Posted at 7:50 AM ET, 05/17/2010

NextBus predictions -- not so accurate

By Washington Post editors

Metro's bus prediction system is even less reliable now than when the transit agency deemed it so inaccurate as a pilot that officials pulled its plug, the Washington Examiner reports.

The NextBus system, which uses GPS signaling to help predict when a bus will arrive at a given stop, currently forecasts bus arrivals 78 percent of the time correctly, according to Jack Requa, who oversees Metrobus operations.

That is far below the system goal of 92 percent. It's also even less than the 80 percent prediction rate the smaller pilot version had in October 2007, when Metro officials decided to "pause" the system because it was not accurate enough.

By Washington Post editors  | May 17, 2010; 7:50 AM ET
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That's unfortunate. Hopefully, the system will become accurate. Fortunately, for me, for the buses I ride, it is usually accurate to within 2 minutes for buses predicted to arrive in 20 minutes or under. There seems to be a 2 minute delay in the system. When I check my mobile device and it says the bus is 0 minutes away, usually it appears about 2 minutes later. Other than that, I haven't really had any complaints and the information has been accurate enough on the bus routes I take.

Posted by: PersonL | May 17, 2010 8:46 AM | Report abuse

I have to complement you again for linking to a local competing paper.

Posted by: iolaire | May 17, 2010 9:42 AM | Report abuse

NextBus was a good idea but it and any other predictive system can not account for traffic congestion IN FRONT of the bus. The system ASSUMES a bus is travelling at a set speed. This would work most of the time during non-rush service.

Imagine giving someone in Baltimore a precise time when you will get there. Of course you wouldn't. You know that there might be congestion somewhere between DC and Baltimore but you don't know the effect of the congestion on your predicted time.

Posted by: Jimof1913 | May 17, 2010 11:46 AM | Report abuse

I have found Nextbus to be semi-helpful. I ride along East West Highway on the J2/J3/J4 buses during rush hour. There is usually a bus every 15 or 20 minutes and Nextbus is often very accurate.

My problem is that once or twice a week I encounter "ghost" buses. I track a bus for half an hour as it gets closer and closer to my stop - and then it just disappears and I have to wait 15-20 minutes for the next one. An equal number of times I will be facing a long wait for a bus when one will suddenly appear. Could it be the SAME BUS? This is so spooky that it would be cool.

It sounds like I need to go back to complaining to WMATA since the absence of actual complaints seems to make them think that everything is going just great! Idiots.

Posted by: wp05122010 | May 17, 2010 11:48 AM | Report abuse

Much Ado About Nothing....

Posted by: 4thFloor | May 17, 2010 12:18 PM | Report abuse

What does this inaccuracy include? I find that buses often arrive a few minutes later that predicted, and that's no big deal. However, I also find that some buses don't appear on NextBus at all, and some buses appear but never actually arrive. It seems that many of the inaccuracies that I have experienced could probably be attributed to operator error rather than inaccuracy inherent to the system.

Posted by: jw703 | May 17, 2010 12:58 PM | Report abuse

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