So I was on my way home today...driving along a road that the police frequent often with their stupid little radar traps!

My passport starts going off giving me enough time to slow down for mr policeman.

when i reach the top of the hill and go over i notice its not a patrol car, but one of those mobile speed machines....you know the ones that display your approaching speed.

I thought i would have a little fun and vary my speed to see how accurate my speedo was.

I was always under the assumption that the speedo was about ~1% fast, meaning actual speed is slower than shown.

To my surprise, the speedo was showing exactly 1MPH faster than this machine and therefore my actual speed.

Of course, another thought was that the speedo machine was also not 100% accurate - does anyone know if they have a tolerance or are exact?

I always thought that there was a greater tolerance with our speedos, and never slowed to exactly the posted limit, probably 3-4 over thinking i would be okay....now this shows ill have to be a little more accurate!

Still, one good thing....my confidence in my passport grows more every day, especially as i got unbelievable warning in this situation and it was an "over the hill" type situation.

any body else had experiences with these machines???

 

The speedo machines are generally GROSSLY inaccurate. If you want to get your TRUE speed, buy or borrow a good GPS unit.

-P

 

The radar detectors are generally pretty accurate for most situations you are likely to encounter.

However, as your velocity approaches the speed of light or c, you run into problems from Einstein's theory of special relativity.

 

Thanks for that Barry, though i am sure if my velocity was approaching c in a 35mph zone I would be kissing goodbye to my license....as well as my a$$

 

Yeah e=mc2 and all that. Glad to hear the passport is working for you though I drive my stook naked.

 

obviously a gambling man douge

it was the first thing I put in the S (stole it from the wife's trailblazer!)

much cheaper than speeding tickets!

 

We had one of those radar trailers set up on a side street by my house. If you were going 5 MPH over the speed limit, it would blink red at you.

Even more irritating was that the cops set up a speed trap right behind it to catch people who sped up just to mess with the radar on the trailer.

 

There's one of those speedo machines on my commute to work (on the highway), and it's also a speed trap with lots of cops in the vicinity. However, I start work pretty early, so in the mornings, the cops have not yet arrived, and I can "play" with the machine as well. I'd have to agree that they don't seem very accurate at all. They don't always reflect changes in speed accurately, and they sometimes detect changes in speed when there are none.

 

Don't try to steal one, they have lojack in them. This one was parked infront of my house.

 

I just drove to Vegas last weekend. They have those frickin' things spaced out pretty well along the way. I kept getting alerts every 25-50 miles or so, and it was almost always one of those radar carts. I would also see an occasional CHP, but I think they are using those unmanned devices to spread out their officers.

After a while, I didn't even speed up after passing it. Guess it did its job on me.