I was told by an SFMTA official that there is no way to stop a motorist who is so reckless that they'll blow red lights and go 100 mph on city streets. Too many engineers and planners don't get that their street designs are what make reckless driving possible in the first place. Most of San Francisco's streets are so wide and straight that speeding is not just possible, it's almost encouraged.
But imagine driving 100 mph through this intersection in Paris:
It doesn't matter if you're Mario Andretti or Mr. Magoo, go much faster than 20 and you will hit a pole or a tree. Steel poles and the traffic cop of physics make it impossible to speed. Those poles were added specifically to force drivers to slow down as they navigate between Rue Lamark and Rue Caulaincourt.
Using physical obstacles to narrow lanes, tighten turns, control speeds, and stop encroachments is understood in the Bay Area on some level. But instead of steel, the city relies on "silly straws," better known as safe-hit posts, to encourage motorists to slow down and stay in their lane.
I've watched cars drive over entire blocks worth of safe-hit posts. It's such a common problem, the SFMTA couldn't even manage to find a picture for its Tenderloin safety project web page that didn't include a broken safe-hit post:
I've asked, multiple times, why the SFMTA continues to use plastic straws instead of steel or concrete to force motorists to slow down and stay in their lanes. It's not that K-rails, steel posts, and concrete planters are prohibitively expensive or difficult to install. I was told on the q.t. that the city just doesn't want the liability from its installations smashing up people's cars.
Use Physics, Not Plastic, for Safety