The adoption of 511 Systems has led to an annual $4.7 billion savings in travel costs and 175 million hours saved in travel time.

The London School of Economics and Political Science examined the benefits ITS has had on mitigating traffic congestion in the United States.

Date Posted

Mitigating Traffic Congestion: The Role of Intelligent Transportation Systems

Summary Information

To empirically assess the impact of ITS on traffic congestion, a longitudinal dataset of 99 U.S. Metropolitan Statistical Areas (MSAs) over a period of 21 years from 1994 to 2014 were consolidated by integrating multiple data sources. The unit of analysis is an MSA as designated by the U.S. Census Bureau. 

The main analysis relies on the traffic data from the Annual Urban Mobility Scorecard (AUMS) maintained by the Texas A&M Transportation Institute. The AUMS is a comprehensive dataset that integrates highway performance data from the Federal Highway Administration (FHWA), and traffic speed data collected by INRIX10 on 1.3 million miles of U.S. urban streets and highways. To incorporate road network information, the AUMS dataset was matched with the Highway Performance Monitoring Systems (HPMS) data for each MSA. The HPMS data contains administrative and roadway system information (e.g., road miles, vehicle miles traveled) on all public roads, including interstate highways, freeways, arterials/collectors, and local roads. 


  • The difference-in-differences estimates show that the adoption of 511 Systems is associated with a significant decrease in traffic congestion, saving over $4.7 billion dollars and 175 million hours in travel time annually in U.S. cities.
  • 511 Systems reduced about 53 million gallons of fossil fuel consumption and over 10 billion pounds of CO2 emissions.

Two theoretical explanations are offered for this effect:

  1. ITS help individual commuters to make better travel decisions; and
  2. ITS help local governments to develop an urban traffic management capability.

Empirical evidence supports the underlying theoretical mechanisms and shows that ITS help commuters to schedule travel more efficiently, choose better navigation routes, and optimize their work-trip transportation mode. Second, the effect of ITS is contingent upon road supply and public transit services.

Results Type