Dale –


Wyoming has fully implemented one segment of Variable Speed Limits and is in the process of rolling out several more segments in the near future after a successful study of the test site.   The speed limit is adjusted for the segments where the weather (or other) conditions warrant based on real time traffic speed data.  More details at:  and


I have heard rumors that WSDOT has had discussions with WYDOT ITS about VSL (possibly for Snoqualmie Pass).


FYI, Under the 2009 MUTCD regulatory variable speed limit signs are to have a white legend. See attached interpretation from FHWA’s MUTCD Team.


Wyoming also has a chain law that can apply to road segments during adverse weather.  This is an alternative used to keep roads open.  More details are available at:



If I can provide further information, please let me know.



Adam Larsen

Safety Program Engineer

FHWA Wyoming Division


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-----Original Message-----

From: FHWA Freight Planning [mailto:[log in to unmask]] On Behalf Of Dale A Tabat

Sent: Monday, November 29, 2010 12:28 PM

To: [log in to unmask]

Subject: Inclement weather speed limit reductions


The Washington State DOT is interested in information on the following:


1) Are there any states that decrease the posted speed limit in the event of inclement weather (snow and ice in particular) and if so how is that accomplished? Is the speed limit decrease applied to specific road segments only or can it be incorporated across a state's entire highway system?


for related information for all traffic in general and freight trucks in particular.


2) Are there any urban areas that issue chain requirements for freight trucks during snow/ice conditions?


Thank you for any input.


Dale A Tabat

Truck Freight Program and Policy Manager Washington State Departemnt of Transportation [log in to unmask]