Driving Simulator Study of Signing for Complex Interchanges

This paper documents a driving simulator project that identified driver lane changing behavior for six topics related to freeway guide signing at complex interchanges. Forty-two drivers from rural and urban areas of Texas used a desktop driving simulator to navigate fictional destinations by following test guide signs. Driver peformance measures included lane change proximity to interchanges and number of unnecessary lane changes. In addition, subjective measures of comfort and confidence were obtained. Almost all participants made the correct decision to exit or stay on the freeway with an option lane; however, many unnecessary lane changes were made with each of the three sign sets. For the sign set that had an arrow per lane design when signing closely spaced interchanges, all participants made correct lane change decisions. While several incorrect lane changes were made for each sign set used to evaluate signing for a Y split, the sign set that used split exit signs at all three sign bridge locations had the fewest, and was judged superior. The topics that evaluated if it is better to fill an advance single sign with supplemental wayfinding information, or to spread the information among multiple signs found that spreading information about the next exits across multiple signs on a single bridge may have unintended consequences if the sign for another exit is located to the left of the preferred lane. The topic that evaluated driver understanding of left exit signs found minimal difference between the two sign sets tested.