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Rancher_Will's avatar
Rancher_Will
Explorer
Oct 05, 2015

Construction Site Speed Monitors

This is a question that has been in my mind for years. I wonder if others have noticed it.

I regularly drive, with and without our RV 5th Wheel RV, in locations where special speed signs, perhaps radar reading, post the speed that each vehicle is moving at the site. Such signs at school crossings, construction sites, etc., are common. These signs usually follow warning signs that speed is restricted ahead.

In our area all of the local speed signs, such as school area or school crossing signs, or other such signs, register almost exactly the speed that I am moving when they show the speed and changing speed. So I know that my speedometer(s) must be accurate.

However, I have noticed that on the Interstate Highways, the speed signs at construction sites almost always read about 5 MPH faster than my speedometer reading in my vehicle as I approach and pass the sign.

Has anyone else noticed this too? I often think it the sign is set on purpose so that traffic will slow down even slower than the posted speed limit at those sites.
  • It would seem reasonable to set the highway speed signs a little higher than actual. People are caught up in the rush of traffic, they are in a frenzy of doing the max + 5mph. I would do the same thing.
  • As soon as I see the mph sign, I peak at my dash. Always a bit lower than my actual speed. I see it as a way to slow us down, but I sure don't use that sign as a way to see if my gauges are working properly. And I never use it to slow me down......
  • On a similar note, I've noticed when I go to a doctors office and get weighed, I'm always 5 pounds heavier than at home.
    I have a couple scales at home and they're all within a pound.
    But, it seems all the doctors office scales show 5 pounds more.

    Maybe, it's for the same reason construction radar shows you're going faster?
  • It's probably because most people go 5mph over the posted speed limit.
    Jim
  • I've noticed the signs reporting 5mph too high around my city, I also wonder if it's a way to try to further slow people down.
  • I agree. It's probably for the safety of the workers. That's a good thing.

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