Have you ever been stuck in gridlock traffic while running a few errands and wondered why so many other cars are on the road? If so, you're not alone. Transportation researchers at Georgia Tech are examining the commuting habits of 500 drivers in the metro area in a study that's become the largest of its kind ever conducted on vehicle travel patterns.

Drivers who volunteered to take part in the study allowed researchers to install a small, electronic box in their vehicles, developed by Georgia Tech researchers, called the "GT Trip Data Collector." About the size of a car CD player, the device uses global positioning systems to record the movement of vehicles and various engine data, as well as where, when and under what conditions people drive in the Atlanta area.

The research team, led by Randall Guensler, a transportation professor in the School of Civil and Environmental Engineering, says the data could be used to help city planners decide such matters as what streets are in need of stoplights, which are prone to bottleneck traffic, and which have become heavily-used shortcuts.

"We can use this information about how people travel in Atlanta to better plan the future of our regional transportation system," Guensler said. "The data will provide a wealth of information for possible use in congestion mitigation, signal timing improvement and roadway design improvement."

Called "Commute Atlanta," the project is sponsored by the Federal Highway Administration, the Georgia Department of Transportation and Georgia Tech. The research team recruited 275 households to participate in the study. So far they have already collected data from more than 100,000 trips.

In the study, data such as speed, position and acceleration are tracked as drivers go about their daily routines. The data are so accurate that if a participant's vehicle was stolen, researchers could locate the vehicle using the equipment.

The information is uploaded, via a cell phone connection, to a main computer at Georgia Tech, where researchers monitor the travel patterns. The data identifies locations of recurrent traffic congestion on highways and arterial roads, and gives precise details on such information as what time it occurs, what days are the heaviest and how long it tends to last.

For example, on one stretch of Interstate 75 in the Atlanta area, "… if you arrive between 7:05 and 8:20 a.m., it's going to take you a significantly longer amount of time to get through that section," Guensler said.

Although Guensler and his group gain important data from the data trip collector, position data doesn't tell the whole story. So the team supplied each driver with a travel diary to better understand the types of trips each was making at various times of the day.

Looking at the commuting data of one of the drivers during the course of one week, Guensler pinpoints the driver's trips to the grocery store, daycare, home, school, healthcare, a drop-off at MARTA and two work locations. The trip data collector assesses traffic flow patterns from location to location - information drivers could use to choose better routes to take from point A to point B in order to cut their commuting times.

Nationwide congestions surveys typically rank Atlanta among the top cities for traffic congestions, with the average rush-hour driver wasting about 55 hours per year in traffic, according to an annual report released this month by the Texas Transportation Institute at Texas A&M University. The report notes that congestion extends to more times of the day and more roads, creating more extra travel time than in the past.

Guensler says the information his group is collecting could be useful to planners to help them prioritize improvements to the regional transportation system in order to obtain the biggest congestion reductions, at the least cost, and as quickly as possible.

Although Commute Atlanta is designed to provide critical transportation planning data for the Atlanta region, Guensler said it is also designed to serve as the starting point for a planned research effort that would evaluate the potential effects of cent-per-mile automobile insurance pricing. The Commute Atlanta project would establish baseline travel patterns for all of the 275 participating households, who would be invited to participate in a pay-as-you-drive insurance research study.