As gasoline prices have risen to unprecedented levels over the past 2 years, many transit agencies have claimed that higher fuel prices have driven ridership growth. It is determined first whether such a correlation is substantiated by the available data and then, if such correlation exists, the nature of this relationship. Five U.S. cities were selected for analysis on the basis of their level of automobile orientation and the extent and variety of transit services: Atlanta, Georgia; Dallas, Texas; Los Angeles, California; San Francisco, California; and Washington, D.C. Most of the transit systems in the five cities analyzed have experienced ridership growth since early 2004. Exceptions include the Atlanta bus and heavy rail systems and the San Francisco bus systems. With the use of time series analysis, seasonal indices, and correlation coefficients, ridership trends are evaluated and compared with corresponding national fuel prices. With the exceptions of the modes cited above and the Virginia Railway Express commuter rail in Washington, D.C., the correlation between ridership and fuel prices is statistically significant for all systems. This finding indicates that fuel price increases have indeed played a role in encouraging transit use in historically automobile-oriented American cities. Finally, the empirical relationships between fuel price and transit demand are explored. Results indicate that, on average, as fuel price increases by 1%, transit demand increases on the order of 0.24%; in other words, ridership increases approximately 0.09% for each $0.01 increase in fuel price.

Bicycling as a mode of transportation is increasingly seen as a healthy alternative to motorized transportation modes. However, in congested urban areas, the health benefits of bicycling can be diminished by the negative health effects associated with inhalation of particulate matter. Particles of small size (ultrafine particles <0.1 μm) are the most harmful, even during short-duration exposure. Because vehicular exhaust is the major source of ultrafine particles, the impact of traffic levels and bicycle lane characteristics on exposure of bicyclists was studied. Ultrafine particle exposure concentrations were compared in two settings: (a) a traditional bicycle lane adjacent to the vehicular traffic lanes and (b) a cycle track design with a parking lane separating bicyclists from vehicular traffic lanes. Traffic measurements were made alongside air quality measurements. The cycle track design mitigated ultrafine particle exposure concentrations for cyclists. Results showed statistically significant differences in terms of exposure levels for the two bike facilities, as well as correlations between traffic levels and exposure level differences. Results also suggested that ultrafine particle levels and spatial distribution were sensitive to proximity to signalized intersections. Findings of this research indicated that, in high traffic areas, bicycle facility design had the potential to lower air pollution exposure levels of bicyclists.

Transportation departments are beginning to recognize that adaptation for climate change must become an integral part of their planning efforts. However, staff members frequently lack the adequate local data, training, and guidance needed to begin adaptation planning assessments. As a result, planning for adapting to climate change has remained generally abstract and lacks the specificity needed to identify potential system vulnerabilities, assess risk, and prioritize responses. This report outlines a geographic information system–based method with which transportation departments can assess vulnerabilities to climate change in their multimodal surface transportation systems. The city of Portland, Oregon, is used as an illustrative case study. The proposed method allows for preliminary vulnerability identification, prioritization, and impact assessment and can also be used as a basis for more advanced analysis and scenario testing. This research also identifies and describes data gaps and other barriers to climate change adaptation planning for surface transportation.

Research efforts in the past decade have produced a wealth of knowledge about the likely impacts of climate change on transportation infrastructure—effects witnessed to date as well as those anticipated in coming decades—the effects of which frequently conflict in both magnitude and scope. This research summarizes the findings of the surface transportation climate change literature and explores the efforts under way in the transportation planning realm with respect to adaptive preparations of transportation infrastructure for the effects of climate change. This research focuses on transportation facilities and operations in the Pacific Northwest region of the United States. This report builds on recent research on governmental climate change planning efforts to explore how agencies in Alaska, Idaho, Oregon, and Washington are preparing for climate change in their climate action plans, to investigate how the goals and recommendations of those plans are reflected in long-range transportation planning documents, and to identify key resources and strategies agencies may adopt to ensure that the anticipated impacts of climate change on transportation are addressed in transportation planning documents.

Previous research has shown a relationship between gasoline price and public transportation use. Although the magnitude, direction, and volatility of this relationship vary by mode, location, and system size, there can be no doubt that recent fuel price growth and fluctuation have affected most U.S. transit systems. The research presented here explores the relationship between transit ridership and fuel price, among other operational and external factors. This investigation found that after seasonal effects were removed from the ridership data series for 254 transit systems, the effect of gasoline price on bus patronage varies regionally, with the North Central and Midwest sections of the nation displaying trends that oppose conventional wisdom and differ from the rest of the country. Plausible reasons underlying these trends, including the regional effect of alternative fuels such as E85, are hypothesized and elaborated on by using federal data on ethanol availability and consumption.