The Effectiveness of Auditory Side- and Forward Collision Avoidance Warnings on Snow Covered Roads in Conditions of Poor Visibility
Kathleen A Harder, John Bloomfield, Benjamin J Chihak
Report no. Mn/DOT 2003-14
Because the snowplow operator's tasks are predominately visual, warnings presented visually may interfere with critical tasks. Auditory warnings could reduce visual load if they are meaningful, effectively signal danger, and are not annoying. We conducted a driving simulation experiment-using a 210-degree forward field-of-view driving simulator-and a field test to investigate using auditory icons as side- and forward-collision avoidance warnings. Participants in the experiment drove on simulated snow-covered roads in 105-meter (344-feet) visibility conditions. Analysis of data from 28 participants showed the side-collision avoidance warnings were equally effective; lane change response times were approximately 1.1 seconds for both a single- 187/ double-beep car horn warning-although participants said the double-beep warning sounded more urgent. Analysis of the forward-collision avoidance warning data, obtained from 32 participants, showed the mean response time with a warning consisting of two bursts of screeching-tire sounds was significantly faster than with a singlescreech warning-with both warnings significantly faster than the mean time obtained when no warning was given. The poorest collision outcomes occurred with no warning-outcomes were better with the single-screech warning, and better still with the double-screech warning (which the participants said sounded more urgent than the single-beep warning). In the field test, six of seven snowplow operators preferred the double-beep side-collision warning. We recommend an auditory icon sounding like the double-beep of a car horn be used as a side-collision avoidance warning and an auditory icon sounding like two successive bursts of screeching tires should be used as a forward-collision avoidance warning. A driving simulation experiment was conducted to investigate auditory icons as side- and forward-collision avoidance warnings. The auditory warnings produced significantly faster mean response times than with no warning, and participants preferred a double-beep side collision warning over a single-beep warning. Researchers recommend a double-beep auditory warning similar to the double-beep of a car horn for side-collision avoidance and a forward-collision avoidance warning similar to two successive bursts of screeching tires.