Do Ride-Hailing Services Worsen Freeway Congestion and Air Quality? Evidence From Uber in California

CERE Working Paper, 2022:1

67 Pages Posted: 24 Mar 2022

Date Written: January 31, 2022


Ride-hailing (RH) services, such as Uber, have become a significant component of urban transportation over the past decade, affecting many aspects of transportation. We investigate the effects of Uber upon freeway traffic outcomes and pollutant concentrations in California, where freeway congestion and air quality is among the worst in the U.S. We use a panel difference-in-differences design and exploit variation in the entry of Uber into different counties in California using hourly freeway traffic data and daily pollution data for the 2009-2015 period. Our findings show that weekday freeway congestion and PM2.5 concentrations decreased at an average county following Uber’s entry. However, we find that much of this reduction occurs in the off-peak time periods and in less populated counties. During the evening rush hour and in the most populated counties, congestion actually worsened and NO2 and O3 concentrations increased. We provide suggestive evidence that counties with low public transit ridership and higher vehicle registrations are associated with worsened congestion following Uber’s entry, suggesting these channels are important reasons for reduced congestion.

Keywords: Air Pollution, traffic congestion, ride-hailing, ridesharing

JEL Classification: R4, L91, C21, C23

Suggested Citation

Krishnamurthy, Chandra Kiran B and Ngo, Nicole S., Do Ride-Hailing Services Worsen Freeway Congestion and Air Quality? Evidence From Uber in California (January 31, 2022). CERE Working Paper, 2022:1, Available at SSRN: or

Chandra Kiran B Krishnamurthy (Contact Author)

CERE, Umeå ( email )

Almas Allé 10
Umeå, 750 07


Nicole S. Ngo

University of Oregon ( email )

1280 University of Oregon
Eugene, OR 97403
United States

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