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Title:

Effects of Reduced Visibility from Fog on Car-Following Performance

Abstract:

The goal of the present study was to examine the effects of reduced visibility of scene information from fog on car following performance. Drivers were presented with a straight roadway scene in a driving simulator and were asked to maintain a predetermined driving distance in response to speed variations of a lead vehicle. Lead vehicle speed varied according to a sum of 3 prime sine wave frequencies. Five simulated fog density conditions and 3 average lead vehicle velocities were examined. Car following performance was assessed using distance headway, variance of distance headway, RMS velocity error, control gain, phase angle, and squared coherence. Distance headway decreased only at the highest fog density condition examined. RMS velocity error increased with an increase in fog density. These results indicate that drivers had greater difficulty responding to changes in lead vehicle speed as compare to changes in headway. The results for squared coherence indicated that the effects of fog were greatest for the highest rate of change in lead vehicle speed (i.e., the highest frequency examined). The importance of visual factors for optimal car following performance is discussed.

Source(s):

87th Transportation Research Board (TRB) Annual Meeting, University of California-Riverside. For an electronic copy of this resource, please direct your request to WeatherFeedback@dot.gov.

Date: 2008

Author:

Kang, Ni, Andersen

Keywords:


Fog
Driver behavior
Speed

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