Michael A. Knodler
This research explores the relationship between the cross-sectional design elements and the impact on selected driver attributes such as speed profiles and lateral positioning. In this experiment a traditional collector type base roadway of 1.5 miles with 14 ft travel lane and 8 ft shoulder was modeled using a fixed base driving simulator. The base scenario was subsequently reconfigured with four different cross-sectional design with various elements within the same physical right-of-way. Specific design elements included, narrower lanes, bicycle lanes, raised center median and a curvilinear roadway profile. A within subject’s design of twenty participants who drove each of the five developed scenarios, which were presented in a counterbalanced fashion to mitigate any potential order effect. Participants’ speed and lateral position was recorded throughout each of the drives. Across the virtual scenarios the same performance measures were analyzed by comparing data at each of five controlled collection points (checkpoints). Analysis of experiment results was performed using both descriptive and inferential statistical tests of speed and lateral position data. vii The obtained results show that the mean participants’ speed was higher than the posted speed limit in all scenarios, except the for the curvilinear profile scenario. There was no statistically significant difference in speeds between the base scenario (Sc1), narrower lane width (Sc2), bicycle lane (Sc3) and raised median (Sc4); however, for curved scenario (Sc5), the difference in speeds were statistically significant. There were significant differences in lateral position between the scenarios across the checkpoints. Overall, the results suggest that narrower lanes, or bicycle lanes, or raised median has no significant influence on reducing the speed. Nevertheless, narrower lanes have influence on maintaining the vehicle lateral position towards the center lane.