It’s a luxury tenfold.
A few extra minutes inside your apartment on a windy February morning instead of waiting at the bus stop – all because you accessed real-time transit information on your smartphone.
But when you get to the bus stop at the time your phone said the bus was coming, the bus is nowhere to be found. Huh?
It turns out that real-time information isn’t as accurate as we think (or hope). Here’s why:
A screenshot that demonstrates how the real-time information provided by transit agencies can lag behind current GPS tech.
Transit agencies typically supply real-time information to passengers through automatic vehicle location (AVL) and computer-aided dispatch (CAD) systems. An AVL system is a GPS that’s built into the bus. The CAD system helps bus dispatchers keep bus drivers on-schedule and reroute around incidents.
When AVLs were first rolled out, they reported their location to the CAD system every 3-5 minutes through radio. Nowadays, the AVLs of large transit agencies report data every 30 seconds via LTE or 3G, according to Chris MacKechnie, a planner at Long Beach Transit and a public-transportation expert.
Smaller agencies are mostly stuck in the past, though. The operations director of Greater Bridgeport Transit in Connecticut told me that since its AVL is reported through radio, when the buses reach particular radio “dead zones,” bus locations are lost – and hence, real-time info – for 15 minutes or more.
Communicating a bus’s location to the CAD isn’t the only problem with AVL/CAD systems, though. Since CAD needs AVL in order to work, AVL and CAD systems are often sold as a bundle by the same vendor. This means that transit agencies might not be able to replace their AVLs for cheaper and more reliable GPS systems that report location more frequently (such as smartphones) without getting rid of their CADs.
Using smartphones as GPS systems is exactly what the DC Circulator did in 2015. As Mobility Lab reported, the Circulator partnered with EastBanc Technologies to combat bus bunching by installing a smartphone in each bus. The smartphones report a bus’s location every three seconds, giving bus dispatchers much more accurate real-time information to avoid bunching.
And, riders have more accurate real-time information, too. In my own assessment of location reporting times (using the app Transit), the updated location of Circulator buses appears every 15 seconds, whereas WMATA’s Metrobuses update every 50 seconds.
Independent programmers are trying to make real-time info more accurate as well. Transit and Moovit, two public transportation apps, now use crowdsourced data to complement the real-time info they receive from transit agencies. (Think Waze.)
This means that when a rider is using the trip-planning feature or presses “Go” (as in the case with Transit) and boards a bus or a train, the app uses the rider’s smartphone to track where the vehicle is. So if you get on the 96 bus (as I did last night) and press “Go,” the app will use your smartphone to give riders down the line much more accurate real-time information – meaning updates every second, instead of every 15 or 50.
But why, when it’s just a difference of a few minutes, does any of this matter? If you’ve ever taken public transportation, you know why.
For example, take my waiting for the 96 bus last night. When I left my apartment, the bus was eight minutes away. When I got to the bus stop, it was 11 minutes away. Five minutes later, it was eight minutes away. And then two minutes away. And then three minutes away. I was about to give up and call an Uber when the bus bounded around the curve, like a triumphant racehorse trotting around the track.
Okay, maybe not quite like that. But this is why accurate real-time information matters.
Real-time info can reduce the uncertainty of using public transportation – the anxiety from being unable to plan when you’ll reach your destination. Real-time info makes it easier for people to use the existing infrastructure. And it might even increase ridership.
With this in mind, maybe transit agencies should throw out their AVL/CAD systems and invest in smartphones and unbundled CADs.
Photo by Elvert Barnes/Flickr.