Maximum allowable change in speed limit between signs

[civilman72]

I'm trying to find a reference to determine the maximum allowable incremental change in speed limits between signs.

As an example, you are driving in town on a rural highway and the current posted speed limit is 30 MPH. When you drive out of town the speed limit on the highway goes up to 60 MPH. So in this example, can there be one sign outside of town with a 60 MPH posted speed limit? Or if there is a maximum allowable incremental increase (say 15 MPH), then there would have to be a 45 MPW sign between the 30 and 60 MPH signs.

Does it make any difference in the requirement if the speed is being increased or decreased?

Not sure if this a federal regulation or state mandated, but I thought I've seen this type requirement in the Colorado Department of Transportation regulations, but am having a hard time finding it again. Maybe it was under the MUTCD in temporary traffic control section? Not sure... any guidance would be appreciated.

 

[ACtrafficengr]

It's not in the MUTCD. You may have a state law or regulation that requires speed limits to be stepped down.

From MUTCD Section 2B.13 Speed Limit Sign (R2-1)

Guidance:
09 A Reduced Speed Limit Ahead (W3-5 or W3-5a) sign (see Section 2C.38) should be used to inform road users of a reduced speed zone where the speed limit is being reduced by more than 10 mph, or where engineering judgment indicates the need for advance notice to comply with the posted speed limit ahead.

 

[ACtrafficengr]

Here's a link where you can find your state manual or supplement, if there is one:
[link]http://mutcd.fhwa.dot.gov/resources/state_info/index.htm[/url]