This research showed that San Francisco's road congestion significantly worsened between 2010 and 2016. Based on monitoring data from the SF Transportation Authority's Congestion Management Program, peak arterial speeds decreased by 26% for morning commutes, and by 27% in the evening. On a typical weekday, total vehicle hours of delay increased by 40,000 hours, and vehicle miles traveled increased by over 630,000 miles. Transportation network companies (TNCs) accounted for approximately 50% of the change in congestion in San Francisco between 2010 and 2016, as indicated by three congestion measures: vehicle hours of delay, vehicle miles traveled, and average speeds. Employment and population growth—encompassing citywide non-TNC driving activity by residents, local and regional workers, and visitors—are primarily responsible for the remainder of the change in congestion.
Given the significant worsening of congestion in San Francisco in recent years, a critical question is whether, and to what degree, TNCs have affected congestion. Using the congestion measures, data, and methods previously described, it appears that TNCs contributed approximately 50% of the overall increases in congestion in San Francisco between 2010 and 2016, although this varies widely by neighborhood and time-of-day. Employment and population growth—an expression of greater economic activity in the city that encompasses the driving activity of all non-TNC travelers/motorists—account for the other half of the increase in congestion.
San Francisco County Transportation Authority. (2018, October). TNCs and Congestion. San Francisco, CA. Retrieved from