An inexpensive new “smart city” system could help improve local bus services by collecting data from passengers’ mobile phones.
Developed by transportation engineers at the University of Washington, the system uses Wi-Fi and Bluetooth signals from passengers’ smartphones and other mobile devices to gather data about where bus riders get on and off, how many people use each bus stop and even how long they wait to transfer to another bus.
Sensors costing about $60 (£41) per bus detect a unique identifier called a media access control (MAC) address associated with a particular mobile device as it boards and leaves the bus, providing complete and real-time travel data.
According to the developers, the system only collects MAC addresses and the time and location they are detected from Bluetooth or Wi-Fi signals, and each address is anonymised for privacy protection.
The new system is potentially a more reliable way of gathering data compared to the traditional methods of passenger surveys, head counts and smartcard swipes that may only offer partial information about how people are using the bus network. It could help bus operators make decisions about changing routes or service levels, and determine how frequently buses should run and whether larger buses are needed at certain times of day.
One of the challenges in developing the system was to collect enough data to yield an accurate picture of travel behaviour. The developers also had to filter out all the signals from mobile devices running Wi-Fi or Bluetooth carried by people who were near the bus but not actually riding on it.
“That’s probably the hardest part of the whole thing,” commented co-author Kristian Henrickson, a UW civil and environmental engineering doctoral student and research assistant who manages the university’s Smart Transportation Application and Research (STAR) Lab. “The big things we’re concerned with are pedestrians and cyclists or people in cars or buildings that have their Wi-Fi and Bluetooth devices on and are close enough to have the sensors on the bus pick up those signals. So we have to make sure we filter out those addresses.”
In the initial tests of the system, the sensors mounted inside the buses picked up more than 20,000 unique addresses. But after weeding out signals that were unreasonably long or short, or that appeared or vanished far from a bus stop, the researchers ended up with 2,800 “trips” that they are confident were taken by passengers on the bus.
The origin and destination data from the remote sensing system matched information that the researchers collected by riding buses and tracking how many people got on and off at various stops.
“We were able to prove the concept and demonstrate that it’s much cheaper to collect data this way,” said senior author Yinhai Wang, a UW professor of civil and environmental engineering and director of the Pacific Northwest Transportation Consortium, or PacTrans. “This is really just at the beginning stage, but this technology is going to become more universal in the age of smart cities.”
Tags: real-time travel data