Sensing the Way to Better Public Transit
Industrial Engineer – Volume 48, Number 5

Bluetooth, Wi-Fi can help planners determine passenger data in real time

In the future, your Wi-Fi or Bluetooth signal could lead to better public transit. University of Washington transportation engineers have developed an inexpensive system to sense those signals from bus passengers’ mobile devices, collecting the kind of data that transportation agencies perennially desire, such as where riders get on and off, how many people use a particular stop and how long they wait to transfer to another bus.

The sensors, which cost only about $60 a bus, detect a unique identifier called a media access control address associated with a mobile device as it boards and leaves the bus. The system is more cost-effective than traditional passenger surveys, head counts and smart card swipes that may only offer partial information about how people are using the transit network.

Another challenge was developing processing algorithms to filter out signals from the mobile devices of people who were near the bus but not on it. The sensors initially picked up 20,000 unique addresses. Weeding out signals that were unreasonably long or short or that appeared or vanished far from a bus stop yielded 2,800 trips.