COMMENTS ON EFFECTS OF VEHICLE TYPE AND AGE ON DRIVER BEHAVIOR AT SIGNALIZED INTERSECTIONS

A recent paper in the literature reported that driving patterns at a signalized intersection were correlated with the type (e.g., small, standard-sized) or vehicle being driven. This report stimulated the authors to reexamine data previously collected on driver response to the amber light at two signalized intersections, one with a 48 km h to the minus one power speed limit and the other with a 80 km h to the minus one power speed limit. Our analyses provided no evidence that when actually confronted with an amber light, drivers of different vehicle type produced different driving patterns. However, there were effects which can be associated with vehicle age at the 80 km h to the minus one power intersection, the drivers of newer vehicles being more likely to drive into the intersection after the light had turned red. Drivers of "standard-sized" vehicles had higher approach speeds and deceleration levels than drivers of "non-standard-sized" vehicles. Also, drivers of newer vehicles used higher deceleration levels than drivers of older vehicles. These findings are used to offer a possible explanation of the result relating driving patterns to vehicle type previously reported in the literature. The data are also used to illustrate the practical existence of theoretically predicted "dilemma zones." /Author/