Operational Effects of Slow Vehicle Turnouts on a Rural Highway in Alaska

摘要

The Sterling Highway is a two-way, two-lane rural principal arterial located on the Kenai Peninsula of Alaska that connects Homer to Soldotna and areas north, including Anchorage. Annual average daily traffic (AADT) in 2013 varied from 5,300 vehicles per day to 2,400 vehicles per day throughout the 70-mile study corridor; however, there is significant seasonal variation in traffic volumes such that typical summer time traffic is 150% to 200% of AADT. The Sterling Highway carries significant levels of recreational vehicles or vehicles pulling a trailer. Twenty-two slow vehicle turnouts (SVTs) were constructed on the 70-mile section of the Sterling Highway between Homer and Soldotna in the summer of 2014. Prior to this, there were no passing lanes or designated SVTs within the project area. Speed, volume, and gap data were collected in the project area both before and after construction of the slow vehicle turnouts. Prior to construction, the expected operational benefit was calculated in terms of change in percent impeded dependent upon the percentage of leading vehicles using the turnouts. This paper reports on the actual change in percent impeded and makes conclusions about the efficacy of slow vehicle turnouts for operational improvements.