I'd like to update last night's post with an addition: My reasoning is that the biggest idiots of them all are the ones who slide off the road and go crashing into the fire hydrants.
As you can see, sometime last night (or early this morning) someone drove completely off the road at the corner near my house and ran directly into a fire hydrant (knocking it completely over), which somehow magically didn't explode with water. I'm not sure why, exactly, it failed to do so.
Seattle gets so much rain that fires just naturally go out. The hydrants are there for public morale.
Here in Seattle we treat fires as first-class citizens, and fully expect them to go out and have a good time every once in a while.
The bolt on the top of a hydrant turns a shaft that opens or closes the valve. Sometimes the valve is below ground. If the hydrant was hit in such a way as to not really effect the lower part of the shaft, water wouldn't come out, even if the hydrant was completely sheared off.
It's almost as if they considered that something like this just might happen to the fire hydrant.
It also appears dry hydrants are installed to prevent water in the hydrant head from freezing, which seems like a bigger problem than the occasional errant idiot driver.