Publications
“The Marginal Cost of Traffic Congestion and Road Pricing: Evidence from a Natural Experiment in Beijing” (with Jun Yang and Shanjun Li)
American Economic Journal: Economic Policy, (2020) 12(1): 418-53
American Economic Journal: Economic Policy, (2020) 12(1): 418-53
Marginal External Cost of Congestion
|
Severe traffic congestion is ubiquitous in large urban centers. This paper provides the first causal estimate of the relationship between traffic density and speed and optimal congestion charges using real-time fine-scale traffic data in Beijing. The identification relies on plausibly exogenous variation in traffic density induced by Beijing’s driving restriction policy. Optimal congestion charges range from 5 to 39 cents per km depending on time and location. Road pricing would increase traffic speed by 11 percent within the city center and lead to an annual welfare gain of 1.5 billion Yuan from reduced congestion and revenue of 10.5 billion Yuan.
|
“Does Subway Expansion Improve Air Quality?” (with Shanjun Li, Yanyan Liu, and Lin Yang)
Journal of Environmental Economics and Management, (2019) 96: 213-235
|
Major cities in China and many other fast-growing economies are expanding their subway systems in order to address worsening air pollution and traffic congestion. This paper quantifies the impact of subway expansion on air quality by leveraging fine-scale air quality data and the rapid build-out of 14 new subway lines and 252 stations in Beijing from 2008 to 2016. Our main empirical framework examines how the density of the subway network affects air quality across different locations in the city during this period. To address the potential endogenous location of subway stations, we construct an instrument based on historical subway planning, long before air pollution and traffic congestion were of concern. Our analysis shows that an increase in subway density by one standard deviation improves air quality by two percent and the result is robust to a variety of alternative specifications including the distance-based difference-in-differences method. The total discounted health benefit during a 20-year period from reduced mortality and morbidity as a result of 14 new subway lines amounts to $1.0–3.1 billion, or only 1.4–4.4 percent of the total construction and operating cost.
|
Subway Network Density in Beijing
|
Working papers
Traffic congestion and air pollution are pressing challenges facing middle-income countries. Lost time due to congestion negatively impacts growth while air pollution adversely affects public health. To address this issue, governments have pursued a host of policies including driving restrictions, public transit fare reductions, and subway expansions. However, there is limited empirical evidence regarding the relative effectiveness and efficiency of such policies in developing country settings. In this paper, I estimate the welfare effects of various congestion-reduction policies for Beijing, which has some of the world’s worst pollution and congestion problems. Specifically, I compile a detailed dataset which allows me to recover individuals' full transportation mode choice sets. I then leverage this information in a discrete choice framework to estimate consumer preferences for travel time and cost; to examine the substitution patterns among different travel modes; and to generate counterfactual simulations for travel demand, mode choice and consumer welfare under alternative transportation policies. My estimates suggest that the elasticity of driving with respect to travel cost is 0.03, a substantially more inelastic response than found in the prior literature. In addition, my simulations show that the driving restriction has had a larger impact on improving the average travel speed than other traffic congestion policies (existing or proposed), resulting in reducing cost of congestion by 17 billion yuan, or 2.6 billion dollars. Based on my model, a regulator wishing to achieve the same goal of the average speed of 42km/h could subsidize public transit by 26.7 yuan per ride; restrict 3 out of 100 drivers on the road; charge 26.3 yuan within the 3rd ring road as a cordon toll; or impose road pricing of 0.46 yuan per kilometer.
“Roads as a Network and Congestion Pricing: Evidence from High-Frequency Traffic Data” (with Shanjun Li)
“Understanding Heterogeneity in the Value of Time” (with Ziye Zhang and Shanjun Li)
“Social Exclusion and Subjective Well-being” (with Tauhidur Rahman)