News Release

University of Florida Engineer's Computer Model Calculates Hidden Cost Of Some Traffic Delays

Peer-Reviewed Publication

University of Florida

A Dollar Figure For Inconvenience

GAINESVILLE --- You're late to work after being stuck in traffic around a bridge repair. Relax. A computer shares your pain. University of Florida civil engineers are at work on a computer model that will help Florida Department of Transportation (DOT) engineers figure in "user costs" in determining when to repair or rebuild bridges. These costs reflect the indirect results of detours and slowdowns around bridge repairs, including commuters' missed work, added expenses for gas and wear and tear on their cars -- even the number of wrecks that might result if planners were to leave the bridge open.

"These are very important factors, and we're trying to feed them into the overall decision-making process," said Fazil Najafi, an associate professor of civil engineering and a specialist in public works, planning and management.

A total of 346 of Florida's 5,800 state-owned bridges need repairs, said Richard Kerr, bridge management inspection engineer for the DOT in Tallahassee.

In the past, the DOT has scheduled repairs around the needs of a single bridge or a group of bridges, figuring in user costs on an individual basis, Kerr said. The data used in the calculations has not been as solid as the agency would have liked, and the lack of a statewide system has sometimes resulted in overlapping projects, he said.

To remedy the problem, the agency is at work on a computerized "bridge management system" that will have consistent standards for user cost and many other variables, such as the condition of the bridge and planned new bridges in the area, Kerr said. The goal is to make the most needed repairs with the least amount of inconvenience to commuters or truck traffic, he said.

"User cost will be a significant factor, but it will not be the overriding factor," Kerrsaid. "It will be 10 to 20 percent."

Najafi said he will rely on other studies and state bridge data to create a structured model. For example, the model will seek to determine added accidents caused by allowing the bridge to remain unrepaired using past traffic and crash data from the area, and other similar areas.

There are no plans to try to put a dollar figure on driver frustration, though Najafi said he may try to quantify this variable in the future.

"It's true that when you go through a frustration process you're not functioning properly" and that could be quantified using lost work or health data, he said.

Kerr said assumptions must be made to create the user cost models, so 100 percent accuracy of the models is impossible. But, on balance, the systems are useful, he said.

"Meteorologists model weather systems and tell us we're going to get X amount of hurricanes, then what happens isn't quite what they predicted, but you have to do the best you can with the information and tools you have available," he said.

Writer: Aaron Hoover
ahoover@ufl.edu
Source: Fazil Najafi
(352) 392-1033

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