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Analysis: Traffic-slowing construction projects have doubled in SF in past decade

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An analysis has found that the building boom in Downtown San Francisco is leading to slower drive times on some roads. (James Chan/Special to S.F. Examiner)
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Downtown San Francisco development is booming, but the cost of sprouting highrises may be measured in hours behind the wheel.

Records show permits for construction-related traffic mitigation from the San Francisco Municipal Transportation Agency have nearly doubled in the last 10 years, painting a clearer picture of the far-reaching impacts of construction.

Separately, an analysis of traffic arteries near heavy construction projects downtown, conducted for the San Francisco Examiner by Inrix — a global traffic, parking and population movement analytics firm — found that more construction slowed traffic as much as 9 mph during the morning commute on particular downtown streets.

Inrix found significant traffic slowdown near corridors with comparably higher numbers of construction sites, based on a map of permitted construction assembled by the Department of Building Inspection and traffic speeds compared before and after construction began. Inrix used Market Street as a control to account for other factors.

“From a 30,000-foot level, downtown road networks are stressed,” said Bob Pishue, transportation analyst at Inrix. “A small disruption from construction or road closures can have a disproportionately large impact.”

Inrix offered the data with caveats that it is difficult to account for every other variable on city streets, like lane eliminations or road construction.

Still, the numbers were stark: First Street southbound between Market and Harrison streets, for instance, showed a slowdown from 2015, before a number of construction projects began there, to this year, when construction was well underway for a 60-story office building, a 42-story mixed-use building and other projects.

From before construction to after, average travel speeds dropped from 11 miles per hour to about 4.7 mph. By contrast, free-flowing traffic on that street at 2 a.m. travels at about 14 mph.

“From the data, it appears that travel speeds have generally declined on certain streets, like First Street and Harrison,” Pishue said. “Construction is likely adding on to other factors and impacting travel times [and speeds].”

That trend continued throughout corridors with major construction downtown, Inrix found, though some streets fared worse than others.

Segments of Howard, Harrison, Sixth and Bryant streets, all of which stretch past higher levels of permitted construction, showed average traffic speeds slowed from 3 to 4 mph during commute hours, with some variability.

SFMTA spokesperson Paul Rose said roadway construction is generally guided by the requirements included in a city policy reference guide known as the “Blue Book,” which contains a list of streets where lane closures are allowed and where lane closures require permits.

Generally, The City continues to allow work during non-rush hours and limits work on the busiest streets during the times of heaviest use, Rose said.

“If a roadway closure or lane closure is expected to cause additional congestion, the construction crews may be required to install detour signage, advanced warnings, pay for parking control officers or other measures to mitigate those impacts,” Rose said.

SFMTA data shows construction that specifically impacts streets has doubled in recent years.

When construction requires closing a street, alley, sidewalk, movement of a bus zone or other similar requirements, contractors must file for a “special traffic permit” with the SFMTA.

In fiscal year 2007, which spans July 2006 to July 2007, 1,955 such permits were issued. That number dropped in fiscal year 2010 to 1,345 permits issued.

But as San Francisco’s economy has boomed, so has construction impacting traffic: Starting in 2013, special permits issued jumped to 2,935. By 2016, 3,945 permits were issued.

“While we don’t measure congestion in general, we know that San Francisco’s economy has grown over the last several years, and construction permitting has increased as well,” Rose said. “That combination can put more vehicles and people on city streets.”

Recently, businesses led by the San Francisco Chamber of Commerce began a downtown traffic congestion working group and are working with the SFMTA to better manage congestion.

Dee Dee Workman, vice president of public policy at the Chamber, said work is underway to bring more of the developer and construction community to the table to talk traffic.

“That conversation is going to happen,” she said.

However, she noted many factors are slowing downtown traffic, like ride-hails and Public Works projects.

“It’s like a perfect storm,” Workman said.

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