Mix together a Category 5 hurricane, monumental grid lock, and a creative civil engineer — and what you get is a clever new way to find the path of least resistance through stop-and-slow traffic on jammed highways and major surface arteries during emergency civic evacuation.
The new technique monitors Bluetooth signals from commuter cell phones to derive travel times, road speeds and vehicle movements. Normally, Bluetooth wireless communication technology connects and exchanges information for cell phone hands-free headsets, wireless keyboards, Internet access for personal digital assistants and wireless networks for laptops and personal computers. Darcy Bullock, a professor of civil engineering at Purdue, found a way to use wireless Bluetooth signals to provide low-cost tracking data on everything from the speed of the morning commute to the sluggishness of airport security lines, to aiding in the emergency evacuation of entire cites.
"I was on the faculty at Louisiana State University in the 1990s, and later watched how hard my colleagues worked to dynamically plan and adjust routes during the Katrina evacuation," Bullock says. Planning evacuations on the fly, while the storm is raging, leaves ample room for improvement.
When the wind died back, Bullock set out to see if he couldn't devise a method that uses pervasive Bluetooth signals from cell phones and other wireless gadgets to track and monitor how long it takes vehicles to travel from one point to another on freeways or major surface arteries.
Such a capability would give law enforcement and emergency managers a layer of visibility they don't currently have to devise better routes and allocate resources. Although the system was designed to be used during mass evacuations by emergency managers and law enforcement, a major benefit of Bullock's system is it can be used every day to time traffic signals more intelligently, or manage traffic through construction work zones to reduce congestion.
This is how it works. Every Bluetooth device has its own distinct digital identification signal, called a media access control, or MAC. By mounting a simple whip antenna on power poles adjacent to roadways or on freeway overpasses, the digital MAC address of devices can be easily read, logged and time-stamped. If these MAC addresses are logged at multiple locations, the unique MAC addresses can be matched, and the difference in time stamps can be used to calculate travel time.
Law enforcement and emergency planners could use the data to make informed decisions about how to allocate resources or adjust evacuation routes during civic crises. If the information were made public, commuters or evacuees could access the travel-time information using the same portable electronic devices that make the system possible, or the data could be used to display travel times on message signs.
"Information is a commodity people are aggressively seeking, and this method promises to cost-effectively provide information that has never been widely available to either commuters or emergency managers," Bullock says.
Last year, Bullock's Bluetooth scheme was implemented at six interstate locations on I-465 and I-65, and two major surface arteries in the Indianapolis metropolitan area the week of the 2008 NASCAR Brickyard 400 auto race. On race day, nearly 19,000 unique MAC addresses were captured at the eight locations.
Using that information, travel time estimates were provided to Indiana Department of Transportation (INDOT) mobile data terminals. After the race, INDOT processed the data to obtain travel time plots and origin-destination matrixes to provide a quantitative evaluation of race day traffic management operations.
Bullock believes his Bluetooth technique improves on existing traffic monitoring methods, most of which rely on roadside sensors or closed-circuit television cameras.