Michael Knodler and Mark Hamin

Publication Date



Protected intersections are an integral component of Complete Street networks and are used to facilitate and delineate the route cyclists should take while traveling along a protected network. The separation from the travel lane of automobiles, however, causes a decrease in driver attentiveness to cyclists. Rates of incidents of cyclists, specifically with right turning vehicles, have increased in recent years, leading to a desire to improve the safety benefits of existing protected intersections to increase the visibility of cyclists and driver awareness. This research used a simulated environment to test the effectiveness of different pavement markings and intersection radii on the speed and attentiveness of drivers. Participants were recruited to drive twelve scenarios in a simulated world and their speed, position, braking behavior, and glance pattern were analyzed to determine what combination of variables leads to the highest increase of safe interactions between cyclists and automobiles in a protected intersection. A speed and regression analysis were conducted to determine which variables influenced participants speeds the greatest, thereby improving the level of safety in the intersection. It was found that the size of the protected elements, the presence of a cyclist, and a participant’s gender were all significant in influencing the speed at which drivers navigated the intersection (p<0.05) for right turns. The slowest speeds were recorded when a larger intersection radius was used in conjunction with a dashed white line through the protected intersection, suggesting that the combination of those two variables are effective in improving the level of safety for cyclists and motorists in a protected intersection.