An Analysis on the I-405 High Occupancy Tolls in Washington State

Abstract

In September of 2015, the Washington State Department of Transportation (WSDOT) by approval of state legislature, opened the express toll lanes on the auxiliary highway known as Interstate 405 (I-405). Part of a master plan1 to improve one of Washington’s most congested highways2. WSDOT’s objective was to add a dynamic tolling system to improve commutes in both South and North directions of the highway3. In this paper, I will examine the efficiency4 of the I-405 High Occupancy Toll (HOT) lanes using commuter data provided by WSDOT for the year 2017-20185 through regression models I created. It is important to further investigate into the efficiency of tolling systems as it becomes more commonly utilized by several state departments of transportation across the United States as a method to moderate congestion. Through this analysis, I hope to add additional information to help further develop an understanding and to provide feedback on its efficiency. The current HOT pricing model is guided by a mathematical algorithm that manages toll rates from real time traffic and updates every ten minutes with a maximum charge of $10. Although this analysis requires additional future research, I concluded that the I-405 HOT lanes have not been operating above forty-five miles per hour ninety percent of the time during the peak hours that it was required to be according to the Revised Code of Washington 47.56.880. As a result, there appears to be little differentiation from the HOT lanes to the general-purpose lanes in terms of congestion moderation.