Paul Sorensen

SKAGIT COUNTYWIDE AIR, RAIL, WATER, AND PORT TRANSPORTATION SYSTEM STUDY

Skagit County, a rural county approximately 96 km (60 mi) north of Seattle, Washington, and 120 km (75 mi) south of Vancouver, British Columbia, is experiencing strong growth in population and employment. Much of the increase is expected to occur in sectors that generate freight. Substantial growth in goods movement is expected at the county’s intermodal facilities. Decision makers realized that a major factor contributing to the economic growth in the county was its relatively unconstrained access to major markets in the north and south. They also understood that the efficient movement of people and goods is dependent on an integrated multimodal transportation network. The main purpose of the Skagit Countywide Air, Rail, Water and Port Transportation System Study was to provide in-depth analysis of the movement of freight, according to mode of transportation (i.e., road, rail, water, air, and pipeline). The methodology used to estimate existing, and forecast future, freight traffic flows by mode and by location is presented.

Understanding the Potential of Variable Tolling to Smooth Congestion on Downstream Facilities: Applications of a Joint Time-of-Day and Route Choice Model

The aim of this research was to understand the conditions under which time-varying tolls could be used to effectively smooth congestion on a downstream, untolled roadway. This question was answered in the context of the 183A Turnpike in Texas, but the analysis was extended to draw lessons for the potential use and evaluation of time-varying tolls as a congestion management strategy elsewhere. The study relied on two primary data sources: license plate reader data, to observe traffic routing, and a stated preference survey, to understand travelers’ trade-offs between travel time, tolls, and time-of-day shifts. A joint time-of-day and route choice model was developed and implemented in a spreadsheet for the rapid evaluation of a range of scenarios. Model inputs were then varied across key dimensions to achieve a better understanding of the conditions under which such a strategy might or might not be effective. The analysis revealed that under the conditions and constraints specific to the 183A corridor, time-of-day tolling would have a limited effect, but that there are a range of conditions for which time-of-day tolling could be a cost-effective means of managing downstream congestion.