Shorter driving time, but greater risk? A&M engineers test navigation tools

Time for a road trip. You punch the destination into your GPS and choose the suggested route. But is this shortest route the safest? Not necessarily, according to Texas A&M University researchers.

Dominique Lord and Soheil Sohrabi, with the help of funding from the A.P. and Florence Wiley Faculty Fellow at Texas A&M, designed a study to examine the safety of navigational tools. Comparing the safest and shortest routes between five metropolitan areas in Texas — Dallas-Fort Worth, Waco, Austin, Houston and Bryan-College Station — including more than 29,000 road segments, they found that taking a route with an 8% reduction in travel time could increase the risk of being in a crash by 23%.

“As route guidance systems aim to find the shortest path between a beginning and ending point, they can misguide drivers to take routes that may minimize travel time, but concurrently, carry a greater risk of crashes,” said Lord, professor in the Zachry Department of Civil and Environmental Engineering.

The researchers collected and combined road and traffic characteristics, including geometry design, number of lanes, lane width, lighting and average daily traffic, weather conditions and historical crash data to analyze and develop statistical models for predicting the risk of being involved in crashes.

The study revealed inconsistencies in the shortest and safest routes. In clear weather conditions, taking the shortest route instead of the safest between Dallas-Fort Worth and Bryan-College Station will reduce the travel time by 8%. Still, the probability of a crash increases to 20%. The analysis suggests that taking the longest route between Austin and Houston with an 11% increase in travel time results in a 1% decrease in the daily probability of crashes.

Overall, local roads with a higher risk of crashes include poor geometric designs, drainage problems, lack of lighting and a higher risk of wildlife-vehicle collisions.

Lord and Sohrabi, recent civil engineering doctoral graduate and postdoctoral research associate in roadway safety at the Texas A&M Transportation Institute, published their findings in a prominent transportation journal, Transportation Research Part C.

They also propose a new system architecture to find the safest route using navigation systems.

As route guidance systems aim to find the shortest path between a beginning and ending point, they can misguide drivers to take routes that may minimize travel time, but concurrently, carry a greater risk of crashes.

“Our study revealed the potential of commonly used road navigation apps to misguide users toward using a road that carries a higher risk of crashes, which implies the need for considering safety in route-finding,” Sohrabi said. “Developing such a system is, however, challenging. We proposed a system architecture for safe route-finding and highlighted the requirements for and barriers in incorporating safety in navigation apps.”