Transit agencies have a path forward in modernizing real-time arrival information - MobilityLab
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:
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.)