Performance in real traffic environments

Performance in real traffic environments. Previous studies on speed estimation in traffic have been performed in very different scenarios, varying from the complexity of real traffic situations to the simpler and more controlled simulated conditions. The aim of this research was to compare the performance in real traffic environments (road and highway) with a closed track used in some recent experimental studies (Recarte and Nunes, 1996), and to analyze the effect of sex and driving experience on speed estimation. Thirty-six participants (18 male and 18 female, half of each group being drivers and half non-drivers) estimated the speed of the car in which they traveled as passengers. The actual speed values varied in the range of 40 to 100 kph. for road, and 70 to 120 kph. for the highway condition. Linear, logarithmic and power functions have been fitted, but linear fit was the best in most cases. Accounted variances by linear fit were: r(2)=.86 and r(2)=.81, for closed track and open road, respectively; r(2)=.87 and r(2)=.83, for drivers and non-drivers, respectively; and r(2)=.85, for both sexes. Results obtained on the closed track by Recarte and Nunes (1996) were replicated in the same condition and also verified for the conventional road scenario. However, a different pattern of errors was found on the highway. From the viewpoint of psychophysics, the participants were more accurate on the closed track than in real traffic conditions considered as a whole. The differences found between road and highway and the effects of the participant variables are discussed.