Congestion Pricing Policies and Safety Implications: a Scoping Review.

Congestion pricing policies (CPPs) are a common strategy for addressing urban traffic congestion. Research has explored several impacts of these policies (e.g., air quality, equity, congestion relief). The purpose of this review was to synthesize findings from publications examining CPP impacts on road user safety outcomes. We conducted a systematic search of relevant literature in four large research databases (Transport Research International Documentation, Web of Science, PubMed, and Scopus), searching from database inception through January 2021. We identified 18 eligible publications. Safety-related outcomes included overall crashes and injury crashes with stratification by injury severity and road user type (e.g., bicyclist, pedestrian). A majority of the publications examined zone-based CPPs (n = 13) and used observed data involving real policies (n = 10), as compared to a predicted or simulated analysis. Decreases in overall crashes and injuries for some road users were observed (e.g., car occupants). While some studies estimated short-term increases in injuries and crashes for bicyclists and motorcyclists (likely due to shifts from personal vehicle use to other transportation modes and increased exposure), most analyses focused on longer-term impacts and generally found a reversal and eventual decrease in injuries and crashes after a few years. The relative scarcity of safety outcomes in published literature, along with the wide breadth of CPP types, implementation contexts, and outcomes measured, demonstrates that more research on safety outcomes is needed. Cities and regions planning to implement CPPs should consider potential mode shifts and safety supports for all road users (e.g., bicycle and pedestrian infrastructure).

Designing Effective and Acceptable Road Pricing Schemes: Evidence from the Geneva Congestion Charge.

While instruments to price congestion exist since the 1970s, less than a dozen cities around the world have a cordon or zone pricing scheme. Geneva, Switzerland, may be soon joining them. This paper builds on a detailed review of the existing schemes to identify a set of plausible design options for the Geneva congestion charge. In turn, it analyzes their acceptability, leveraging a large survey of residents of both Geneva and the surrounding areas of Switzerland and France. Our original approach combines a discrete choice experiment with randomized informational treatments. We consider an extensive set of attributes, such as perimeter, price and price modulation, use of revenues, and exemption levels and beneficiaries. The informational treatments address potential biased beliefs concerning the charge's expected effects on congestion and pollution. We find that public support depends crucially on the policy design. We identify an important demand for exemptions, which, albeit frequently used in the design of environmental taxation, is underexplored in the analysis of public support. This demand for exemptions is not motivated by efficiency reasons. It comes mostly by local residents, for local residents. Further, people show a marked preference for constant prices, even if efficiency would point to dynamic pricing based on external costs. Hence, we highlight a clear trade-off between efficiency and acceptability. However, we also show, causally, that this gap can in part be closed, with information provision. Analyzing heterogeneity, we show that preferences vary substantially with where people live and how they commute. Even so, we identify several designs that reach majority support.

Design of a heuristic environment-friendly road pricing scheme for traffic emission control under uncertainty.

Road transportation is one of the main sources of atmospheric emissions in many countries and areas. Road pricing, is not only effective for urban transportation management, but also helpful in reducing the negative externalities caused by transportation. In this study, an inexact two-phase minimal emission programming (TMEP) model is proposed for design of the environment-friendly toll scheme with an acceptable road network performance. Through introduction of fuzzy stochastic programming, multiple uncertainties involved in vehicle emission evaluation are dealt with; the Traffic Performance Index (TPI) based constraints are incorporated to reflect the decision-maker's requirements for network congestion management. The solution method is proposed for generating the range of fuzzy stochastic objectives. An optimal toll scheme associated with the minimal emission based flow pattern is obtained through searching for a set of the best and the worst optimal solutions. A numerical experiment and a real-world road network in Beijing of China are used to illustrate the application of the developed method. In the case study, the toll scheme is obtained at the desired congestion level. The effects of emission and congestion abatement are analyzed under different policy scenarios. The proposed TMEP method can generate the toll scheme with obvious improvements in total emission reduction and congestion mitigation.

The effects of road pricing on transportation and health equity: A scoping review.

Road pricing is increasingly considered as an option to support transportation infrastructure costs, manage demand, and reduce emissions. However, the extent to which implementation of such approaches may impact transportation and health equity is unclear. In this scoping review, we examine the differential transportation and health effects of road pricing policies across population groups and geographic region. We conducted a systematic database search of Transport Research International Documentation, GEOBASE, Scopus, and Ovid Medline, supplemented by bibliographic review and internet searches. Fifteen studies were included in the review. The studies evaluated area and cordon road pricing systems in Singapore, London, Stockholm, Milan, and Gothenburg, and had a median follow-up period of 12 months. Outcomes evaluated include car commuting, mode shift to public transit, accessibility to destinations, affordability, welfare, social interactions, air pollution, traffic injuries and deaths, acute asthma attacks, and life expectancy. While more studies across diverse urban contexts and policy settings will be needed to strengthen the evidence base, the existing evidence suggests road pricing has mostly net positive effects related to a reduction in car trips, air pollution, asthma attacks, and road traffic collisions, and increases in life expectancy. Frequency and ease of social interactions were found to be negatively impacted, with fewer visits to family and friends. The population groups that generally fared better across transportation and health outcomes were those with higher incomes, men, and people between the ages of 35-55. Across space, there are benefits for both the areas inside and outside the cordon boundary, but to a greater degree for the area inside. Overall, the evidence base is limited by a narrow set of health-related outcomes and a lack of longer-term studies. We did not come across any studies assessing distributional effects of noise pollution, mode shifts to walking or cycling, or other morbidities in the general population that are not listed above. In addition, there are few evaluations that include non-work trips, therefore potentially missing effects for unemployed populations or women who are more likely to make non-work trips. We find that the limited body of evidence on area and cordon pricing policies suggests these policies are beneficial for a number of transportation and health outcomes, particularly for populations inside the cordon area, but that there may be some degree of inequities in the distribution of the benefits and burdens.