SAN FRANCISCO COUNTY TRANSPORTATION AUTHORITY
San Francisco is an employment hub for a region with booming jobs and population growth. Population growth in the Bay Area, and San Francisco in particular, is outpacing projections. At the same time, employment is growing faster than population: between September 2009 and April 2015, San Francisco’s workforce has increased by 140,000, while the population increased by around 50,000. Housing production, on the other hand, is lagging. This means that a growing number of people are coming to San Francisco for work but live elsewhere and commute into the city.
Vehicle miles traveled, a measure of the total amount of driving, in San Francisco has been declining for over a decade, but there has been an increase since 2011 following the 2008-2009 recession. Luckily, San Francisco has a strong backbone of regional transit, but the economic upturn has resulted in increases in vehicle miles traveled since 2011, resulting in increased congestion and decreased vehicle speeds during peak periods over that timeframe. The San Francisco County Transportation Authority (SFCTA) conducts the Congestion Management Program, which is a bi-annual program conducted in accordance with state law to monitor and mitigate traffic congestion.
Speed is one metric used to measure congestion, and is measured on the Congestion Management Network, which is a set of key driving routes in San Francisco that provide important access for residents and workers. Average speed is measured separately for urban arterial streets and freeways, and is measured during the morning and evening “peak periods,” or rush hours.
AVERAGE SPEED DURING RUSH HOUR HAS DECLINED SINCE 2009
How San Francisco is Performing
The recent increase in vehicle miles traveled corresponds with an increase in congestion, although over the last 15 years San Francisco is well below the peak vehicle miles traveled of the early 2000s. Between 2013 and 2015, in the afternoon peak travel period, average speeds on freeway segments have decreased 3.2 mph (10.8 percent) from 29.5 miles per hour (mph) to 26.3 mph; and on arterial segments by 3.3 mph (20.6 percent), from 16.0 mph to 12.7 mph. In the downtown core of San Francisco and freeways approaching downtown, where roadway expansion is neither feasible nor desirable, traffic speeds are particularly slow. Travel speeds have decreased both for autos and transit, though the increase has been greater for autos.
The Congestion Management Program monitors performance on a network of important driving routes in the city, and links transportation network performance to transportation decisions that are made to inform better land use and investment decisions. Efforts across the City to improve performance of the road network include robust travel demand management (TDM) programs, land use and transportation planning projects to prioritize development and investments across the city and region, and funding and delivering transit and highway infrastructure projects to support near- and long-term transportation needs.
In addition to the average speeds of all vehicles on the road, data is available on the speed of transit vehicles, which is used to calculate a Transit-to-Auto Ratio. This ratio provides a direct comparison of auto and transit travel speeds. If the Transit-to-Auto Ratio is 2, then travel times on transit are twice as long as in a private vehicle for the same length trip (i.e., private vehicles are twice as fast).
TRANSIT-TO-AUTO TRAVEL TIME RATIO IS CONVERGING
Recognizing that the San Francisco’s transportation infrastructure can be used more efficiently to move more people, and in accordance with the city’s Transit First Policy, San Francisco has invested in prioritizing transit. Between 2013 and 2015, the San Francisco Municipal Transit Agency (SFMTA) implemented service increases on 17 lines as part of Muni Forward, Phase 1 of Clay Street Transit-Only Lanes, Haight Street transit only contraflow lanes, more visible red lanes on Market Street, and other transit enhancements. Those investments have begun to pay off, and transit is becoming measurably more competitive with driving. Continued success at improving transit will not only move more people with existing transportation infrastructure, but will also decrease the number of vehicles trying to use scarce roadway space, leading to a better experience and less congestion for those who choose to drive.
How Performance is Measured
The SFCTA uses INRIX data, a commercial dataset which combines several real-time GPS monitoring sources with data from highway performance monitoring systems, as the primary source for official speed and Level of Service (LOS) calculations. INRIX data is supplemented with floating car data where INRIX data is not available. This method was adopted in the 2013 CMP after initial conducted as part of the 2011 CMP found that results calculated from INRIX were appropriate for use in speed and LOS calculations. The 2011 analysis found that speeds from INRIX data were, on average, higher than speeds from floating car runs, but fell within the range of variability of floating car results for a given segment and time period. Prior to 2013, the SFCTA used the floating car method to collect travel time data on the CMP network.
The AM peak period is defined as 7:00 a.m.-9:00 a.m., and PM peak as 4:30 p.m.-6:30 p.m. Congestion monitoring is conducted in the spring season, and is scheduled to take place at times that are representative of overall traffic conditions. Monitoring is scheduled to avoid holidays, during periods when school is out of session, or during major events.
Transit-to-Auto ratios are calculated on CMP segments where at least 50% of the segment is covered by a transit route. The overall ratio is calculated as the weighted average by length of segment for all segments.
The number displayed on the scorecard page represents the most recent data from the average speeds chart above.
- Read about the Congestion Management Program on SFCTA’s website.
- Learn more about congestion throughout the region on the Metropolitan Transit Commission’s Vital Signs website.
Please click first on the chart above and then click the “Download” button in the bottom right corner of the visualization to view and download the data displayed in the chart.