This report presents the results of the United States Department of Transportation (U.S. DOT) Federal Highway Administration (FHWA) study of methods for before-after measurement of the travel and environmental impacts resulting from congestion pricing projects. Congestion pricing encompasses a variety of strategies which feature transportation facility charges to reduce demand during congested periods, such as high occupancy toll (HOT) lanes which allow vehicles with fewer occupants to pay a charge to access lanes available to vehicles with more occupants at no charge or at a reduced charge.
This report presents a summary and analysis of current before-after practices as well as a set of recommended practices for evaluating the environmental impacts of deployed congestion pricing projects. The summary of current practice is based primarily on a review of published literature pertaining to eight congestion pricing projects from around the world.
The remainder of this introductory chapter provides background information, elaborates on the purpose of this study and summarizes the study methodology. Chapter 2.0 presents narrative summaries of each of the eight study projects describing, for each project, the congestion pricing project, the travel and environmental impact evaluation methodologies, and the reported impacts. Chapter 3.0 draws upon the information presented in Chapter 2.0 to summarize the state-of-the-practice and presents a critical assessment of the strengths and weaknesses. Chapter 4.0 presents the recommended framework for before-after evaluations of the environmental impacts of congestion pricing projects.
Traffic congestion has proven to be a persistent, challenging problem throughout the world. Very significant levels of traffic congestion have persisted and, typically, have continued to increase in many urban areas over the last several decades. The Texas Transportation Institute analyzes traffic congestion data from agencies throughout the United States and publishes results in Urban Mobility Monitoring Reports. The latest available report1, published in 2009 and based on 2007 data, show the following congestion increases between 1982 and 2007:
Although advances in transportation facilities and operations practices have proven useful in the effort to manage traffic congestion, to date, no cost-feasible and politically and environmentally acceptable “solutions” to traffic congestion have been identified. In approximately the last decade, the search for additional strategies to reduce traffic congestion has led to a heightened focus on congestion pricing. Interest in congestion pricing strategies is also, to some degree, a function of increasing interest in roadway revenue collection and financing options—the two strategies can be closely linked. Table 1‑1 identifies various types of congestion pricing projects and some examples of deployed projects and studies. The categories of congestion pricing projects used in Table 1‑1 are those used by the FHWA in their Value Pricing Pilot Program.2
An important manifestation of the increasing focus on congestion pricing in the United States is the U.S. DOT Urban Partnership Agreement (UPA) and Congestion Reduction Demonstration program. Under the UPA/CRD, U.S. DOT has provided a total of approximately $1B shared among six metropolitan areas (Atlanta, Los Angeles, Miami, Minneapolis, San Francisco and Seattle) to deploy integrated sets of congestion reduction strategies that feature various forms of congestion pricing coupled with supporting travel demand management, transit, and technology-based strategies. Table 1‑2 summarizes the UPA/CRD deployments, with the congestion pricing strategies shown in bold type. An important part of the UPA/CRD program is the U.S. DOT evaluation of the impacts of each deployment. Comprehensive assessments of the impacts of the various strategies used at each site are critical both to inform U.S. Federal transportation policy and programs but also to provide guidance to operating agencies who may implement similar strategies.
As congestion pricing projects are becoming more common there is a growing volume of literature describing the projects and their effects. However, there is little published literature on the strengths and weaknesses of prevailing congestion pricing evaluation methodologies. This study is intended to address that deficiency; to summarize current practice and recommend a framework that can inform the UPA/CRD evaluations that are currently in progress and which may also help guide future U.S. DOT or other evaluations.
The primary focus of this study is on the environmental impacts of congestion pricing, including air quality, noise and environmental justice. However, environmental impacts are typically a direct result of travel impacts of projects, such as changes in traffic volumes and roadway speeds. As such, it was clear that this study must also consider how the travel impacts which underlie environmental impacts have been and can best be evaluated.
The study process consisted of the following steps:
The initial scan of published literature utilized extensive Internet-based literature searches as well as some searches of university library and technical journal databases. The initial scan was intended to provide a sketch-level understanding of the number and general nature of congestion pricing projects and studies of those projects worldwide. That understanding also informed the selection of a manageable number of study projects.
Note: Strategies shown in bold type are congestion pricing strategies.
A number of conclusions were drawn based on the initial scan:
The following compiled lists of congestion pricing projects include the projects considered in the initial scan conducted for this study and are available on-line:
Following the initial scan, a subset of congestion pricing projects was selected for detailed literature review based on consideration of the following factors:
Based on these factors, along with practical considerations encountered over the course of the research—namely difficulties in finding sufficient documentation for certain projects—the following eight study projects were selected.
Three of these projects—the Oregon, Puget Sound and Atlanta projects—consisted of before-after (or “with/without”) evaluations of short-term field demonstrations of congestion pricing/revenue collection schemes featuring simulated pricing charges. The other projects all consisted of before vs. after evaluations of fully-deployed congestion pricing schemes with real pricing charges. The eight study projects and associated evaluation methodology and pricing impact results information gleaned from the literature review are described in Chapter 2.0.
After selecting the eight study projects, a second on-line literature search was conducted to obtain as many relevant project documents as possible. In addition to reports focusing on specific congestion pricing projects, this second search identified a small number of congestion pricing synthesis reports, including the following:
All of this project-specific and synthesis literature was analyzed and provides the basis for Chapters 2.0 and 3.0 of this report, and informs the recommendations presented in Chapter 4.0.
1 Schrank, David and Lomax, Tim, “Urban Mobility Monitoring Report 2009,” University Transportation Center for Mobility, Texas Transportation Institute, July 2009.
2 United States Department of Transportation, Federal Highway Administration, “Report on the Value Pricing Pilot Program Through May 2009,” September 17, 2009.
3 United States Department of Transportation, Federal Highway Administration and Federal Transit Administration, “Atlanta Congestion Reduction Demonstration National Evaluation Plan – Draft,” prepared by Battelle, May 2010.
4 United States Department of Transportation, Federal Highway Administration, “Value Pricing Pilot Program: Lessons Learned Final Report.” Prepared by K.T. Analytics and Cambridge Systematics, Inc. August 2008.
United States Department of Transportation - Federal Highway Administration