Freeway delays due to congestion have increased 22 percent from 2014, averaging 3.2 minutes per commuter in 2015. Notably, regional traffic congestion is significantly worse than previous economic booms. Since the peak of the dot-com boom in 2000, per-commuter congested delay has skyrocketed by 50 percent, while population has only grown by 12 percent and jobs have grown by merely 4 percent. This trend is particularly noticeable for Bay Area drivers given that nearly all of the growth in gridlock has occurred during the last three years. Commuters are likely also experiencing delays on arterials and local roads, for which insufficient data is available to quantify key trends.
Time Spent in Congestion
Time Spent in Congestion
We’ve all been there – cruising along at 65 mph only to see a sea of brake lights up ahead in the distance. Traffic congestion is frustrating to drivers, affecting mobility between cities and counties of the Bay Area. Yet at the same time, congestion is usually a byproduct of favorable economic conditions, and many of the nation’s most vibrant metropolitan areas also struggle with congestion.
Congested delay occurs when speeds drop below 35 mph. When speeds fall below this threshold, the freeway corridor begins to operate inefficiently as its capacity declines. While travelers are delayed when speeds are lower than the speed limit (e.g. 55 mph in a 65 mph zone), this is not defined as congested delay as the freeway is actually operating more efficiently at this speed.
While congestion only generates a few minutes of delay for the average commuter, commuters in a handful of high-demand corridors experience far worse conditions. The top 10 most congested segments constitute nearly half of all regional freeway congestion, with just three segments along the Bay Bridge corridor constituting 21 percent all Bay Area traffic congestion. In fact, for the first time on record, AM and PM peak periods have merged into a continuously congested 15-hour period on westbound Interstate 80 from Hercules to San Francisco. This segment was only narrowly eclipsed by the evening commute out of San Francisco on northbound U.S. Route 101 and eastbound Interstate 80 for the dubious distinction as the region’s most congested location.
Over three-quarters of all congested delay on our region’s freeway network occurs in Alameda, Contra Costa and Santa Clara counties. Alameda County alone accounts for over one-third of all regional freeway traffic congestion. The North Bay remains relatively immune from recurrent congestion, accounting for only 5 percent of total delays on a typical weekday – most of which is concentrated on U.S. Route 101 in Marin County.
2015 Time Spent in Congestion on Regional Freeways
Select a congested segment on the map for more information.
Most congested segments
1. US-101 northbound & I-80 eastbound from I-280 to Treasure Island Tunnel
2. I-80 westbound from CA-4 to US-101
3. I-680 southbound & I-280 northbound from S Jackson Ave to Foothill Expressway
4. US-101 southbound from N Fair Oaks Avenue to Oakland Road
5. I-80 eastbound from W Grand Avenue to Gilman Street
6. I-880 southbound from I-238/Washington Ave Exit to CA-237/W Calaveras Boulevard
7. I-680 northbound from Mission Boulevard/CA-262 to Calaveras Road
8. US-101 northbound from Silver Creek Valley Road to N Fair Oaks Avenue
9. I-880 northbound from Mowry Avenue to A Street
10. US-101 northbound from CA-84/Woodside Road to E Hillsdale Boulevard
Los Angeles again tops the list of metros with the greatest amount of total freeway delay. While the Bay Area ranks number 2 on this metric, other dynamic metro areas like Houston and Dallas are roughly in the same league when it comes to traffic delays. This evidence confirms the well-known connection between economic growth and over-burdened highway systems. Metro areas like Philadelphia and Chicago, which have experienced slow growth since the Great Recession, experience delays less than half as severe as the Bay Area.
Metro Comparison for 2014 Time Spent in Congestion
Metropolitan Transportation Commission/Iteris: Congested Corridor Analysis (2015)
No link available
Metropolitan Transportation Commission: Historical Congestion Analysis (1998-2015)
No link available
Texas Transportation Institute: Urban Mobility Report (1998-2014)
California Department of Finance: Population and Housing Estimates
Form E-8 - Historical Population and Housing Estimates (1998-2010)
Form E-5 - Population and Housing Estimates (2011-2015)
California Employment Development Department: Labor Market Information (1998-2015)
Texas Transportation Institute: Unpublished Metro Area Analysis of Severe Congestion Delay (2011)
No link available
U.S. Census Bureau: Intercensal Estimates (2014)
U.S. Bureau of Labor Statistics: Metro Area Employment (2014)
Image: Flickr (Creative Commons license), Photographer: Oran Viriyincy, https://www.flickr.com/photos/viriyincy/4934261108/in/photolist-
Delay statistics only include freeway facilities and rely upon INRIX traffic data. They reflect delay on a typical weekday, which is defined as Tuesday through Thursday during peak traffic months. Delay statistics emphasize recurring delay - i.e. consistent delay greater than 15 minutes on a specific freeway segment. Congested delay is defined as congestion occurring with speeds less than 35 mph and is commonly recognized as inefficient delay (meaning that the freeway corridor is operating at speeds low enough to reduce throughput - as opposed to speeds greater than 35 mph which increase throughput). Data sources listed above were used to calculate per-capita and per-worker statistics; national datasets were used for metro comparisons and California datasets were used for the Bay Area. Top congested corridors are ranked by total vehicle hours of delay, meaning that the highlighted corridors reflect a combination of slow speeds and heavy traffic volumes. Historical Bay Area data was estimated by MTC Operations staff using a combination of internal datasets to develop an approximate trend back to 1998. The metropolitan area comparison was performed for the combined primary urbanized areas (San Francisco-Oakland and San Jose) as well as nine other major metropolitan areas' core urbanized area. Because the Texas Transportation Institute no longer reports congested freeway delay or total freeway delay (focusing solely on total regional delay), 2011 data was used to estimate 2014 total freeway delay for each metro area by relying upon the freeway-to-regional ratio from 2011. Estimated urbanized area workers were used for this analysis using the 2011 ratios, which accounts for slight differentials between Bay Area data points under the regional historical data and the metro comparison analysis. To explore how 2015 congestion trends compare to real-time congestion on the region’s freeways, visit 511.org.