In article >, Jim Yanik wrote:

> Back in 1973 there were highways with 70 MPH speed limits posted,mostly out
> west.If it was safe back then for those lesser cars,then today's limits
> should be much higher.
>
> But they are not,so that kills the idea that limits are 'tuned' entirely.

Occasionally I come across roads that are essentially untouched wrt the
speed limit in the last 30 years or more. It's usually some little two
lane that is signed at 55mph. What is amazing is that these roads are far
more dangerous at 55mph than the interstates would be at 85mph or
higher. Take a typical car of the era that speed limit was posted and
there is no reason for a speed limit at all.

What is even more telling is that sometimes there will be a segment of
road that is untouched. A crappy 2 lane posted at 55mph with bad
sightlines, ditches to either side, etc etc. Then there will be a section
that has been redone. It will be four lanes, a median in the center,
curbs, concrete grooved to prevent hydroplaning, sewers, the whole 9
yards. Both sections see the same traffic, nothing particularly different
along side them. But the new section will have a speed limit that is
10-30mph lower.