Traffic Congestion

How Are We Doing?

The traffic congestion indicator measures the impact of travel time on San Diego commuters due to the increase of vehicles on the road at a particular time, producing slower than expected travel times. Congestion affects the cost to each individual commuter through increased fuel use and lost work hours. The consequences of road traffic congestion affect society as a whole through its impacts on speed and travel time, cost and the environment.

Traffic congestion received a neutral rating because the vehicle miles traveled and vehicle hour of delays in 2020 were impacted largely by the Stay at Home Order issued in March 2020 due to the threat of COVID-19. The impact of the Order on long-term travel patterns is not clear.

Want to know more about what we're measuring?

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Unusual traffic conditions due to pandemic Stay at Home Order

There are many ways to measure traffic congestion - especially because it varies depending on traffic incidents, time of day, weather, work zones, special events, traffic control, and bottlenecks. How reliable the system is to get a person from point A to point B depends on the combination of all of these factors. One metric used to measure traffic congestion is the change in freeway usage across years, measured in vehicle miles traveled (VMT). San Diego freeway VMT per capita is about the same as Orange County, and above the state average. Other Southern California counties, such as Riverside and San Bernardino County, had higher per capita freeway VMT from 2013 to 2018. However, this gap has diminished significantly in recent years, such that in 2019 and 2020, the per capita freeway VMT in San Diego, Riverside, and San Bernardino County were very similar. In 2020, the freeway miles per capita statewide was 13% lower than that in 2019, most likely due to the Stay At Home Order issued in March 2020 due to COVID-19, that limited all non-essential travel. The decrease from 2019 to 2020 ranged from 9% in Riverside County to 21% in Santa Clara County. In San Diego County, the decrease was 19%.

San Diego and Orange County tracked similarly in total VMT over the past eight years, which was much lower than Los Angeles County. Los Angeles County is similar in size (4,751 square miles) to San Diego County (4,500 square miles), but with three times the population. Riverside County, about twice the size of San Diego County (7,303 square miles), and San Bernardino County, three times larger than San Diego County (20,105 square miles), also had similar total VMT as San Diego County, despite the larger land area.

Freeway VMT also varies by day, night, weekdays, and weekends. Weekday peak hours are defined as 6 to 10 am in the morning and 3 to 7 pm in the afternoon and early evening. Miles traveled during peak hours have consistently made up approximately 35% of total freeway miles over the past nine years, even during the pandemic in 2020, while miles traveled during weekday non-peak hours, weekends, and holidays have made up the larger portion of total VMT. The total weekday and holidays freeway VMT in 2020 was 21% lower than that in 2019, and more than the 17% decrease of weekday peak hour VMT during the same period.

Another way to measure traffic congestion is the peak hour delay. The peak hours delay reflects "stop-and-go" severe freeway congestion with vehicle speeds averaging below 35 miles per hour. Tracking the weekday peak hour delay measures how the system is managing the demand of and changes needed to improve the quality of access to work and/or other activities. The freeway delay in the afternoon peak hours is more severe than during the morning peak hours. 

San Diego County drivers in 2019 spent more than 12 million hours on the freeways as a result of delays during the morning and afternoon peak hours. The hours of delay have more than tripled since 2010. However, the peak hour delay in 2020 was 75% lower than that in 2019, at 3 million hours, most likely due to the pandemic and Stay At Home Order. Combined with a 17% reduction in VMT during peak hours, the traffic flow improved significantly in 2020.

Why is Traffic Congestion Important?

High quality of life means the region boasts a thriving economy and a healthy environment accessible to all in the community.

  • Environment: Traffic congestion has negative impacts on the environment arising from decreased air quality and waste of fuel, increasing costs to both individuals and businesses, and increasing greenhouse gas emissions affecting the climate in the long-term. 
  • Economy: Traffic congestion has negative impacts on individuals and the economy. Fuel waste from traffic congestion increases costs to individuals and businesses through increased travel times, costs, and lost productivity. On the other hand, a certain amount of traffic congestion can indicate a thriving regional economy and this is particularly visible in the San Diego border region. As a short-term effort to relieve congestion, the Otay Mesa East project added 20 new lanes and separated cargo from passenger traffic in 2017, which can in the long run serve to increase congestion. The San Diego Regional Chamber of Commerce therefore advocates [link: ] for the re-establishment of a functional cross-border rail system which would significantly improve multimodality and reduce road traffic congestion.
  • Equity: Although San Diego does not rank among the top 10 urban areas in the U.S. for traffic congestion, congested roads decrease air quality, especially in communities in the immediate vicinity. Many of these highly exposed communities are also communities with high concentrations of poverty. 

Regional Response


SANDAG’s 2015 Regional Plan includes an intermodal transit system in San Ysidro (2014 San Ysidro Intermodal Transportation Center final report) with improved and new rail connections throughout the region, as well as congestion pricing to motivate multi-model uses.


The County of San Diego’s Active Transportation Plan (ATP) was approved by the Board of Supervisors in 2018. The ATP provides for increasing biking lanes and walking trails, as well as the safety of non-motorized vehicle users, improves public health and enhances regional efforts to meet greenhouse gas emission goals.


Circulate San Diego in partnership with Rady Children’s Hospital and California Office of Traffic Safety, launched online educational resources and activities to promote safe walking trails and biking lanes.

U.S.-Mexico Border Region

And yet another metric to track traffic conditions is to monitor the number of vehicle crossings that occur from the three land-based ports of entry from Mexico into the United States within San Diego County: Otay Mesa, San Ysidro, and Tecate. In 2020, the total number of northbound personal vehicle crossings at all three ports of entry was approximately 17 million, 24% lower than that in 2019, most likely due to the pandemic related travel restriction that went into effect on March 21, 2020. The San Ysidro port of entry had the highest number of personal vehicle crossings of all ports of entry into the United States in 2020, with 11 million crossings, followed by the El Paso port of entry in Texas with 5.6 million crossings, and the Otay Mesa port of entry with 4.8 million crossings.

When monitoring freight truck crossings, there are two land-based ports of entry from Mexico into the United States within San Diego County: Otay Mesa and Tecate. In 2020, the total number of northbound freight truck crossings, not including privately owned pick-up trucks, at both San Diego County ports of entry was approximately 992,000, 2% lower than that in 2019. The freight movement did not seem to be affected by the border travel restriction, most likely due to its essential nature. About 93% of the freight truck crossings occured at the Otay Mesa port of entry. The Otay Mesa port of entry was the second busiest port of entry in 2020 for freight truck crossings along the U.S.-Mexico border following the Laredo port of entry in Texas.

What Are We Measuring?

We have measured annual change in freeway miles driven per capita and total freeway miles driven in select counties since 2012. For the impact of traffic congestion during rush hour, we have measured the annual hours of delay during morning (6 to 10 a.m.) and afternoon (3 to 7 p.m.) commuter hours since 2006. We also track northbound personal and freight vehicle border crossings into the U.S through the San Ysidro, Otay Mesa and Tecate ports of entry.