Dave Hall wrote:

Most car speedometers are not so accurate that a 1 MPH difference is
all that hard to believe. Just putting one size larger tires on your
car can make that difference.

Well, you're supposed to get your instruments recalibrated after changing
tire size. But differences as much as 5 MPH can happen depending on tire
pressure and road conditions...I've yet to see a speedometer read the right
speed driving on Oregon's notoriously rutted freeways in the rain (probably
because you're forced to hydroplane along the lane, which is why the locals
*will* get aggressive towards tailgaters, though the Californians usually
don't get it until they slam into a wall or the car ahead of them
approaching slower traffic hiding in the road spray of the vehicle ahead
because they're following too close).

People have fought a speeding ticket on this basis and have won.
That's part of the reason why Pa. gives some leeway. Most cops don't
want to have to appear in traffic court when the chances are good the
case could get thrown out. However, it's a lot harder to make a case
for speedometer inaccuracies when you're 10 MPH or more over.

I used to have to deal with police a lot when I was a security officer, and
at one site, the worksite's driveway was a common spot for police to set up
speed traps. The cops don't even bother radar cars until they see someone
moving considerably faster than surrounding traffic, radar the overspeed
vehicle for evidence, and just use the posted speed as something to
estimate a fine from.

They seem to radar everyone in areas where there are actual speed limits
when I see a speed trap in a limit zone. Though I never see anybody pulled
over, everybody just slows down for the speed limit and then drops the
hammer down when it goes back to a posted speed a few miles down the road.

I drive 100 km/h on the freeway even if the posted speed is considerably
lower if the conditions allow, and the cops working the speed trips don't
even look twice and keep looking for someone *really* speeding. Only time
I drive slower than 100 km/h on the freeway is in Salem where there *is* a
speed limit of 60 MPH (about 90 or so km/h), and on I-5, I-405 and US-30 in
downtown Portland, which has a posted speed of 50 but is usually insane to
try for more than 40, and the worst traffic accident in Oregon history was
caused by some ****head Californian who drove his bigrig at 60 MPH into 14
cars stopped in a traffic jam on I-405 while talking on a cellphone and
trying to pick up a CD off the floorpan. That Californian won't be going
back to California anytime soon, he's a prisoner in Salem now for his
criminally stupid behavior.

--
Paul Johnson

http://ursine.ca/~baloo/