Lane Assignment Traffic Control Devices on Frontage Roads and Conventional Roads at Interchanges: Technical Report (0-6106-1)

The intersection and mandatory movement lane control signs placed on intersection approaches are critical to safe and efficient intersection operations. Ramp, frontage road, and cross-street approaches to interchanges often widen at intersections to accommodate additional through or turn lanes. Currently there is inconsistency in conveying to drivers how they should align themselves upstream of a diamond intersection to maneuver for their desired turning movement as the intersection widens. These inconsistencies can result in drivers making incorrect lane selection, which may result in late lane changes or illegal turns. This project conducted state-of-the-practice surveys, focus groups, and driver surveys to develop test signs used for field deployment and evaluation regarding lane assignment on frontage roads and cross streets. The findings include evaluation of an enhanced R3-8 sign to show roadway widening on a frontage road and evaluation of a guide sign to indicate lane choice when approaching a freeway interchange on a cross street. The research provides recommendations on when to apply non-standard singing to more clearly convey lane assignment to drivers on approach to more atypical intersections.