Excessive levels of automobile driving are generally acknowledged to have several negative externalities that contribute to the lack of sustainability in current transport systems. Achieving a reduction in VMT inevitably requires the introduction of disincentives for driving. This has generally been lacking in the US, which has relatively low parking costs and taxes on fuel compared to its developed-world counterparts. However, starting immediately after the Hurricane Katrina disaster, fuel costs in the United States have increased dramatically relative to previous long-term price behavior. This increase has brought attention to the driving behavior and travel preferences of US citizens. A large and possibly long-lasting increase in fuel costs suggests the potential for significant impacts on transport and travel behavior.
One potential impact is a modal shift from the automobile to public transit; however, the ability of transit to absorb reductions in auto travel may be constrained by low service levels in many cities and its low overall national priority. Understanding the potential of public transport to absorb displaced auto travel is critical, yet despite the potential importance of fuel prices in shaping travel behavior, there is remarkably little recent quantitative work on the specific role public transit plays in a scenario of higher fuel costs.
Among the research that has been done, there have been several survey and qualitative policy studies that examined the potential travel response to changes in gasoline pricing. Most of the quantitative research stems from modeling the response to gasoline rationing, allocation plans, and price changes during the oil crises of the 1970’s, and included in some of that research is the role transit can and should play. Other studies have researched the role of gas prices as one of many characteristics in predicting ridership. Recent studies discuss transit ridership in the broader context of traveler responses to various road pricing schemes, including increasing the cost of gasoline.
In this research, a methodology is established for examining the relationship between fuel costs and transit patronage. Data for monthly ridership totals and average fuel prices are compiled for nine US cities. Fluctuations in gas prices between June 2001 and September 2006 are analyzed against transit ridership over the same period. Ridership is modeled as a function of existing cyclical ridership behavior and the variation in gas prices. All transit modes are examined in aggregate, as well as bus and rail independently.
In general, the results of the analysis support the conclusions of other research in the field. There appears to be a small but significant amount of the variability in transit ridership that is attributable to fluctuations in fuel prices. The extent of this influence appears to vary with city size and with transit coverage in the city. The models suggest a relatively inelastic ridership response to increases in fuel prices. It is suggested that those who shift from automobile to transit at high fuel prices are either living near an economic level of being captive users of transit, or were otherwise choosing not to use transit despite already living relatively near available service. The number of people who constitute this group appears to increase linearly with fuel prices. It is also likely that the trips being added to transit at high fuel prices are peak-period work trips. Trips appear to have been shifted from the automobile to the transit mode that provides the greatest level of service within a city.
The results of the analysis have potentially important policy implications. There is a sensitivity to transit ridership from normal fluctuations in gasoline prices. Raising gasoline prices should continue to draw auto users to transit. An important consideration for transit is how well transit operations can handle gas price increases. Both popular literature and academic research have indicated that transit companies are faced with either cutting inefficient routes or raising fares due to the rise in operating costs despite reported increases in ridership. Plans to meet operating costs by reducing service at a time of increased ridership demand can only be bad for the public image of transit as well as for its ability to market itself at a time when transit should be championing its own cause. Transit operators and policymakers might consider subsidizing an expansion of services and enhancing quality at times of high gas prices so as to keep their new patrons should fuel prices fall again. The short-term deficit of doing so might lead to a greater long-term benefit, both for the transit operation and for any broader objective of achieving sustainability in transport. Though few transit operators in the US have such objectives, most research consistently shows that service improvements and expansion lead to increases in patronage. Doing so simultaneous to the arrival of long-overdue constraints on auto use should only enhance that effect.
Available at: http://works.bepress.com/bradleywlane/8/