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October 6, 2020

Traffic jamming: Cell phones could be key to understanding vehicle flow

Written By: Alex Holloway

Partnering with mobile network carriers to access anonymous cell phone location data, traffic engineers could someday leverage mobile network data to monitor real-time traffic speed and density.

 Bin Ran
Bin Ran

“Almost everyone has at least one phone,” says University of Wisconsin-Madison transportation engineer Bin Ran. “Whenever we go somewhere and move around, the cell phone we carry provides that location. By analyzing the anonymous location data of each of our phones, we can tell how fast a cell phone is moving and translate that into congestion data.”

In a paper published in May 2019 in the Journal of Transportation Engineering, Ran, the Vilas Distinguished Achievement Professor in civil and environmental engineering at UW-Madison, shared results of a case study conducted along a major expressway in China that point to the effectiveness of such an approach.

Cell phones have become ubiquitous over the last two decades. According to the Pew Research Center, 96 percent of U.S. adults own mobile phones of some kind, and 81 percent own smartphones. As cell phones have become more popular, mobile networks have evolved, from 1G networks in the 1980s to 5G networks coming online today. These networks not only offer faster connection speeds for users, but an increased ability to transmit phone use and location data.

Ran says the growth in the coverage and intensity of mobile networks offers a chance to leverage that data, which could be useful in two primary ways. The first, he says, is monitoring where people are and how they move around. That could better help engineers understand how traffic moves and how its flow changes at different times of day or for specific events. The second application is using the data to watch for congestion by analyzing how quickly cell phones are moving. Traffic engineers could do that by calculating how quickly a phone passes the network of cell towers near a particular road.

That’s a big shift from traditional traffic monitoring methods, which are limited by where engineers can place physical observation devices. “Traditionally, we want to monitor traffic to observe congestion and see where hindrances like crashes are,” Ran says. “To do that, we have to use some sort of physical device to detect what’s happening at a specific location. That can be cameras or Bluetooth devices. They are something you have to buy and install, and there’s a big demand in traffic operations for monitoring urban streets or freeways.”

Despite its potential benefits, cell phone data does present some challenges. For example, Ran says newer data like what’s carried on 5G networks requires a lot more computing power to use because there’s more of it. He also stresses that it’s vital to ensure that any cell phone data used is anonymous.

While there’s further work to be done to use cell phones to harness traffic data, Ran says the method offers incredible potential for studying traffic flow in areas that are otherwise difficult to do so.

“This could be useful even in rural areas,” Ran says. “For example, in northern Wisconsin, we typically don’t have as much traffic data, because the population is more spread out. In practice, the state transportation department, or the city of Madison, can only put traffic monitoring devices in key locations. Even in Madison, there are many, many places we don’t have them. With cell phones, in theory, if there’s a road, this method is usable.”

Recognizing the potential of this approach, the American Society of Civil Engineers, which publishes the Journal of Transportation Engineering, tapped Ran’s paper to receive the 2019 ASCE Journal of Transportation Engineering Part A Best Paper Award. The honor is based on reviewer ratings, editorial board comments and selection by an awards committee.