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Fall 2001

Troopers say new vision technology could make for safer driving

Photo of patrol car outfitted with the Vision Enhancement System.

Patrol car outfitted with the Vision Enhancement System.

Photo of projected view of approaching curve

View projected on the HUD shows lane boundaries and an approaching curve that would otherwise not be visible to the driver.

In September, members of the ITS Institute's Intelligent Vehicles Lab and HumanFIRST Program tested their Vision Enhancement System (VES) with those who may one day use it on the job.

In a patrol car outfitted with VES technologies, 10 Minnesota State Patrol troopers drove a test track at Brainerd (Minn.) International Raceway and offered opinions about the system that is designed to improve safety under conditions of poor visibility, such as at night or in fog or snow. Safe travel in such conditions is vital for troopers and other emergency vehicle operators.

The VES incorporates technologies first developed for use in a prototype snowplow, including Differential Global Positioning System (DGPS) technology, high-accuracy digital road maps, a "virtual" rumble strip, and a head-up display (HUD). The result is a projected virtual view of the roadway with lane boundaries shown on a screen in front of the vehicle's windshield where the driver can easily view it without looking away from the road. If the driver does stray outside the boundaries, the system issues a warning.

With operational testing of the system scheduled for later this fall, researchers wanted to collect preliminary data on the performance of the VES and examine how the system affects driver speed choice and perception, which may be related to crash risk. The study was led by Dr. Nicholas Ward, director of the HumanFIRST Program. Participating Intelligent Vehicles staff included program director Dr. Craig Shankwitz and research fellows Alec Gorjestani, who monitored the system throughout the tests, and Bryan Newstrom, who created the geospatial database for the racetrack course.

Tests were run at night, and conditions of reduced visibility were simulated by using headlight covers to reduce light transmission. Drivers were given several options for how lane boundaries were displayed on the HUD--longer versus shorter previews, solid versus dashed lines. Officers were told to drive the course at a safe and comfortable speed, except for one section where they were instructed to drive to a set speed without looking at the speedometer.

Afterwards, officers completed a questionnaire from which the researchers assessed factors such as speed perception, mental workload, and user acceptability.

Most troopers reported that they thought the VES would improve safety, particularly on highways and rural roads, but that specialized training would be required to use it and to maintain scanning of the full road scene (thus avoiding "tunnel vision" directed to the HUD).

"All officers reported that they could recognize possible safety benefits for using such a system under very poor visibility conditions," Ward said. Because of the apparent improved safety, all officers had a positive attitude toward the system, he added. Although the troopers noted that the system might require more mental and visual effort to use, they felt it could be used safely with proper training, Ward said.

For preview options, most officers preferred the longer preview on the unfamiliar route because it gave advanced warning of curves ahead, but reached no consensus on a preference for solid versus dashed lines. Based on test results, researchers plan to incorporate some improvements into the system--for example, adding a collision avoidance component. Researchers also learned that any training should emphasize the need for drivers to scan the entire roadway, Ward says.

This research is part of the larger three-year Intelligent Vehicle Initiative (IVI) Field Operational Test Program, which is funded by the Federal Highway Administration, the Minnesota Department of Transportation (Mn/DOT), and industry partners. The IVI project is directed by Mn/DOT, with the Institute's Intelligent Vehicles Lab leading the technology development and systems integration.

The HumanFIRST (Human Factors Interdisciplinary Research in Simulation and Transportation) program is a new effort sponsored by the ITS Institute to conduct research on driver performance and system design in relation to surface transportation.