Modeling Passing Lane Behavior on 2-Lane Highways

Alaska DOT&PF is introducing differential speed limits in passing zones located between Mileposts 59-66 on the Seward Highway. This study will conduct a before/after study to examine the effects of differential speed limits on traffic flow characteristics, along with drivers’ perception of this change. The objectives for the study are (specific details are presented below): (1) To validate the proposed strategy and examine its effects on traffic flow, based primarily on speed in each lane and speed differential between lanes; (2) To measure the change in behavior of drivers passing slow moving vehicles by classification of vehicles driven, as well as those passed (as captured near the middle of the passing zone); (3) To examine the effect on merging behavior of drivers, particularly by measuring the passing demand served versus unserved demand which remains at the end of each passing lane, relative to the legal speed limit as a minimum; and (4) To analyze drivers’ perceptions of the passing zone operation and control using an onsite survey.