Data Snapshot: Twice the fine, half the deaths.
How speed limit enforcement saved lives on the Golden Gate Bridge.
We used to call it the “suicide line.” The only thing separating north and sound-bound traffic on the Golden Gate Bridge were dinky little yellow lane dividers. No parent drove it in that lane when their kids were in the car.
I remember in 1996, there was a really bad accident. Shortly after, officials began enforcing a double fine zone on the bridge. The signs were prominently displayed.
Did it make a difference? Yes.
Speed limit enforcement saves lives.
Last month, I reached out to a Golden Gate Bridge official who gave Inside Medicine some fascinating data. Until 1983, the speed limit on the bridge was 55 mph. In 1983, the limit was lowered to 45 mph. The average number of motor vehicle deaths per year dropped. But that drop also matched rates in San Francisco and Marin overall, as car safety improvements and seatbelts became required. Then, in 1996, a double fine zone on the bridge was announced and enforced. That seems to have made an impressive difference, basically overnight.
Sure, the red line (all motor vehicle fatalities in SF and Marin) continued to drop from 1996-2009, but the drop in average motor fatalities on the bridge (blue bars) well outpaced those improvements. Looking at 1983-1995 versus 1996-2009, the motor deaths in the area went down 39%, on average. On the bridge, the decrease was 77%.
The number of collisions (including non-fatal ones) matches this, according to Paolo Cosulich-Schwartz, Director of Public Affairs for the Golden Gate Bridge Highway and Transportation District. Mr. Cosulich-Schwartz told me that there was “a big drop in collisions in the years after the double fine zone went into effect: 57 in 1995 vs. 37 in 1996 and 22 in both 1997 and 1998).” That makes perfect sense. The double fine zone on the bridge went into effect in mid-1996. As a result, there was a decrease in collisions in 1996, followed by much larger ones in 1997 and 1998 (i.e., the first two full years of enforcement).
It appears that some combination of news coverage and the double fine zone enforcement was associated with a dramatic decrease in fatal accidents on the Golden Gate Bridge.
Think about this. Lives saved, just from posting some signs—and maybe a few extra highway patrol cars keeping tabs on the area. That’s a lot of juice for the squeeze.
Friction-free public health.
In 2015, the Golden Gate Bridge installed a median barrier. The barrier is a perfect example of “friction-free public health.” The idea for the barrier had been discussed for decades, initially rejected as infeasible back in 1985. Finally, after decades of study, a combination of newer technology and increased willingness turned the tide.
And what a difference that has made.
Since the “road zipper” was installed, there have been zero head-on collisions on the bridge. While fatalities had become rare this century—again, owing to the double fine zone, awareness, and improved vehicle safety—there were still major injuries, to say nothing of the massive traffic jams such collisions caused. There were over 100 head-on collisions on the bridge from 1970 until the barrier was built. A 100% improvement is pretty good, I’d say.
Over time, I’ve become more interested in “friction-free public health.” That is, things that exist in the background that we benefit from. For example, wearing a mask when sick is not friction-free, whereas improved air ventilation systems are. Friction-free public health requires investment. But everywhere I look, I see examples of how it works, keeping us safe in ways that we mostly never think about, because someone else has already obsessed about it for far longer. The Golden Gate Bridge’s road safety improvements are a great example of this. We should watch for these and celebrate the successes.
Thanks again to Paolo Cosulich-Schwartz, Director of Public Affairs for the Golden Gate Bridge Highway and Transportation District.
What are some other examples of friction-free public health that you appreciate? Share them in the Comments section.
I was reminded of when highway speed limits were lowered to 55 nationwide (late 1970’s ?” In an attempt to save gas…I bet there were fewer accidents then too… I don’t have any data