40% of San Francisco’s traffic deaths are from left turns. These desig


Drivers turning left are accountable for a disturbingly excessive proportion of pedestrian accidents and deaths within the metropolis of San Francisco. Fixing the issue may very well be a matter of design.

Greater than 300 individuals are injured by left-turning drivers yearly in San Francisco. In 2019, 40% of traffic deaths occurred when drivers making left turns hit pedestrians – largely individuals utilizing crosswalks who weren’t seen by drivers till it was too late. Now, the town is dramatically rethinking its intersections to make these harmful left turns a factor of the previous.

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[Photo: SFMTA]

The scope of the issue grew to become evident again in 2018, when the San Francisco Division of Public Well being analyzed 5 years’ price of left-turn crash information. The company then teamed up with the San Francisco Municipal Transportation Company (SFMTA) to higher perceive why so many deaths have been taking place in left flip conditions. What they discovered was a combination of design points and customary driver behaviors that unnecessarily put pedestrians in danger. To deal with each of these issues, SFMTA launched the Safer Intersections Project to check out new approaches to intersection design, in addition to a $2 million grant-funded public training marketing campaign aimed toward lowering unsafe driving. The trouble is an element of the town’s Vision Zero plan, which goals to get rid of traffic-related deaths.

“Unsafe left turns are not distinctive to San Francisco,” says Uyen Ngo, challenge supervisor and Imaginative and prescient Zero training and outreach coordinator on the SFMTA. “We consider the design interventions and training marketing campaign work are relevant to different cities.”


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[Photo: SFMTA]

On the design facet, the company discovered that half of the rationale left turns are so harmful is that drivers are usually going too quick and turning at too tight of an angle to correctly see whether or not a pedestrian is perhaps crossing the road. This has lethal penalties, notably for older individuals, who make up 31% of pedestrians killed in left flip conditions.

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[Photo: SFMTA]

The intersection retrofits are aimed toward altering the way in which drivers navigate throughout left turns, and embody the position of vertical posts partly inside intersections, six-foot rubber velocity bumps that reach the centerline of journey lanes, and enormous painted zones that present drives the place to not drive. These bodily components drive drivers to decelerate and make extra of a right-angle flip via the intersection versus a quick swooping curve. By making it tougher to show shortly, drivers have extra time to see individuals crossing the street.

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[Photo: SFMTA]

The design interventions have been put in at seven intersections within the metropolis final fall. After a 12 months of monitoring, SFMTA has found that the altered intersections have had important impacts on the velocity and security of left turns. The interventions decreased the typical velocity at which drivers make left turns by 17%, and introduced a 71% discount in drivers taking turns sooner than 15 miles per hour. Extra information shall be collected to see whether or not these interventions end in decreased collisions, accidents ,and deaths.

The interventions are targeted totally on intersections with traffic indicators. Although signaled intersections make up solely 13% of the town’s intersections, they are the place two-thirds of all left flip collisions happen.

[Image: SFMTA]

For almost all of intersections within the metropolis that don’t have these design retrofits, the company is making an attempt to vary the way in which individuals make left turns when driving. Working with behavioral researchers on the Behavioral Insights Team, SFMTA developed particular language to make use of so as to nudge individuals into altering their driving conduct. Via a monthslong marketing campaign of digital, broadcast, and out of doors promoting in a number of languages, the company blanketed the town with messaging emphasizing the truth that 40% of traffic deaths contain drivers making left turns. Via surveys, the company discovered that there’s a larger consciousness amongst residents that dashing is a number one trigger of traffic collisions in San Francisco, and a lower within the quantity of individuals who consider it’s acceptable to drive a couple of miles over the velocity restrict.

San Francisco’s improved left turns are greater than an experiment. These sorts of road engineering adjustments have been carried out in different cities, together with Washington, D.C.; New York; and Portland, Oregon; and research in these cities have proven comparable reductions in velocity throughout turns. SFMTA is now within the course of of figuring out the place else these interventions could be put in place throughout the town. Its Imaginative and prescient Zero plan requires interventions to be put in in 35 extra intersections.


“The advice is to prioritize these remedies at places with present excessive left-turn speeds, conducive road geometry, and much of individuals strolling and biking,”