Research Horizons Magazine
February 9, 2009

Lane Use Management: Monitoring Driving Behavior to Improve Highway Efficiency

Randall Guensler, a professor in the Georgia Tech School of Civil and Environmental Engineering, studies transportation efficiency in metropolitan areas.

Professor Randall Guensler displays equipment used to monitor driver behavior as part of studies on highway efficiency. Georgia Tech Photo: Gary Meek Download 300 dpi version

His current work focuses on close monitoring of real-world driving behavior. The goal: find ways to improve traffic flow by maximizing the use of existing highways.

The vehicle-activity data being monitored are useful, he explains, not only for evaluating travel behavior, but also for studying traffic operations, safety, and environmental impact. Such data can help guide decisions affecting transportation planning and environmental policy analysis.

“Many experts now believe that actively managing lane use can provide greatly improved service without having to construct extra lanes,” Guensler said. “These managed-lane strategies can be implemented for minimal cost, especially when compared to the land and construction cost, the traffic problems and the demolition issues involved in building new roads.”

Guensler and his team are involved in two major projects directly associated with transportation efficiency and managed-lane approaches:

• Commute Atlanta is a four-phase project that examines how monetary incentives, often called value pricing, can influence driver behavior. The $2.3 million joint project, sponsored by the Federal Highway Administration and the Georgia Department of Transportation (GDOT), is also collecting vehicle-use and demographics data useful in studying highway safety and air quality, as well as traffic flow.
• The Congestion Pricing Project, sponsored by the GDOT, uses a variety of techniques including focus groups to collect consumer opinion and other data on lane-management approaches such as value pricing.

The benefits of controlling lane use through value pricing – sometimes called congestion pricing or peak-period pricing – are counter-intuitive, Guensler says. To people sitting in traffic, it looks as if fewer vehicles are flowing through the adjacent limited-access lane because there are big spaces between each car or truck.

Georgia Tech researchers are studying driver behavior in an effort to better use existing highway lanes. Image: Georgia Department of Economic Development Download 300 dpi version

“But in fact if you were looking from the top down, you’d see more vehicles going through that lane every hour than in the congested lanes,” he said. “From an engineering standpoint, traffic flow is the product of vehicle speed and traffic density – that is, the speed of the vehicles and how closely are they following each other.”

To look at it another way, he explains, a small hose that’s flowing freeing moves more water than a large hose that’s blocked.

Commute Atlanta’s first two phases, now complete, examined consumers’ response to having a price attached to their travel practices.

The study selected several hundred representative Atlanta households. Using in-vehicle computers and Global Positioning System (GPS) equipment to collect speed, position and engine-operating data, the study pinned down each family’s average travel habits.

Then each household was offered a monetary rebate for each mile it could pare from its monthly total by any means possible: fewer trips, carpooling, using public transportation, biking or even walking.

Guensler says the study’s first two phases have helped establish research guidelines, but results haven’t been definitive. It’s likely that a larger sampling will be needed to produce statistically significant data. However, he adds, the data already collected from 470 vehicles and more than 1.8 million vehicle trips will be useful in ongoing air-quality and safety research.

The third and fourth phases of Commute Atlanta will simulate the impact of travel behavior on real-time congestion pricing – charging less for restricted-lane travel at off -peak periods. The research also includes installing portable devices on delivery and service vehicles to examine the potential effect of congestion pricing and other pricing mechanisms.

As value pricing of lane use becomes a reality, it’s likely to use a variety of monitoring and toll-collection technologies. To avoid congestion-prone toll booths, future approaches could use technologies similar to today’s cruise cards, which employ radio-frequency identification (RFID) to keep track of a driver’s highway usage.

Another approach could involve on-board vehicle-monitoring systems, which would be in-vehicle devices that use GPS and other techniques to monitor and bill drivers for using special lanes.

The Congestion Pricing Project, a study separate from the Commute Atlanta work, was recently completed for the GDOT. In that project, Guensler teamed with co-principal investigator Catherine Ross, who is the Harry West Professor in the Georgia Tech College of Architecture.

Initially, the Congestion Pricing project reviewed new toll-collection technologies, as well as case studies of congestion-pricing projects in other cities. Subsequently, it interviewed experts on congestion-pricing programs and then analyzed local consumer reactions using focus groups comprised of Atlanta-area citizens.

“Our focus group work revealed interesting points, including the fact that income groups that wouldn’t generally use value priced lanes still liked having them available,” Guensler said. “There are times when everyone finds that these lanes are a good economic decision – such as when you’re late for daycare, and you’re facing dollar-a-minute overtime charges.”

Supporting a $110 Million HOV Toll Lane Project

Under a recently announced plan, the state of Georgia will be the beneficiary of $110 million in federal funds to develop HOV toll lanes along Interstate 85 in metro Atlanta.

The Georgia Tech School of Civil and Environmental Engineering (CEE), partnered with the Georgia Department of Transportation (GDOT), will monitor the effects of the high-occupancy toll (HOT) lane implementation. Georgia Tech has been performing research in support of managed-lane projects since 2003.

Georgia Tech’s activities, led by Guensler, have involved several efforts, including technology development, instrumented vehicle-data collection and analysis of the impact of pricing on traffic and emissions. More recently, working with Catherine Ross’ planning team, the researchers have also completed a series of reports for GDOT that summarize expert panel and focus group results on potential consumer response to congestion pricing.

As the work continues, Guensler will oversee a study that will monitor drivers who choose to use the new toll lanes. His team will track changes in congestion levels, household travel behavior and emissions.

Researchers will also identify potential equity issues in a study that will include 700 households, 1,500 personal vehicles and the express bus fleet. The goal will be to assess the actual travel response and emissions changes that result from implementing the toll project.

Guensler and his team are specialists in the development and deployment of in-vehicle devices to monitor motorists’ driving habits.

For the first two phases of the Commute Atlanta study, researchers developed instrumentation that used an onboard computer and GPS equipment to record numerous driving parameters including location, speed, engine functions and mileage. The team monitored more than 1.8 million vehicle trips on a second-by-second basis. A built-in cellular connection sent back accumulated data weekly.

The third and fourth Commute Atlanta phases are using upgraded equipment that allows real-time tracking of vehicle location, speed, mileage and as many as 10 engine parameters in some monitored vehicles.

Guensler and Jennifer Ogle, now at Clemson University, are principals in Vehicle Monitoring Technology, a new company that is now providing monitoring services for vehicle activity and emissions elsewhere in the U.S.

This article originally appeared in Research Horizons, Georgia Tech's research magazine.

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WRITER: Rick Robinson