See responses with questions below.

-----Original Message-----
From: FHWA Freight Planning [mailto:] On Behalf Of Dale A Tabat
Sent: Monday, November 29, 2010 2:28 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? Looking 
for related information for all traffic in general and freight trucks in particular.

Idaho does not change regulatory speed limits for weather conditions.

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

Idaho has three mountain passes where chains are required certain commercial vehicles when roads are unsafe.  We signify this by using signs that are in effect when lights are flashing.

The legislation looks like this:

49-948 (5)  If the Idaho transportation department determines, at any time, that Lookout Pass or Fourth of July Pass on interstate 90 or Lolo Pass on state highway 12 is of an unsafe condition so as to require chains, as defined in section 49-104, Idaho Code, in addition to pneumatic tires, the Idaho transportation department may establish requirements for the use of chains on all commercial vehicles as defined in section 49-123(2)(c)(i) and (ii), Idaho Code, traveling on interstate 90 or state highway 12. If the Idaho transportation department establishes that chains are so required, the Idaho transportation department shall:
(a)  Provide multiple advance notices of the chain requirement;
(b)  Provide adequate opportunities for pull out;
(c)  Provide notification at a point at which the commercial vehicle can safely pull out of the normal flow of traffic, prior to the point at which chains are required; and
(d)  In no case post requirements for chains on bare pavement.
(6)  Provided that the conditions in subsection (5) of this section are met, the chain requirement shall be met by chaining a minimum of one (1) tire on each side of:
(a)  One (1) drive axle, regardless of the number of drive axles; and
(b)  One (1) axle at or near the rear of each towed vehicle. Such axle shall not include a variable load suspension axle or an axle of a converter dolly.
(7)  Chains as required in subsection (6)(a) and (b) of this section mean "chains" as defined in section 49-104, Idaho Code. Any other traction device differing from chains in construction, material or design but capable of providing traction equal to or exceeding that of chains under similar conditions may be used.
(8)  The Idaho transportation department shall place and maintain signs and other traffic control devices on the interstate and state highway passes as designated in subsection (5) of this section that indicate the chain requirements under subsection (6) of this section.
(9)  Exempt from the chaining requirements provided for in subsections (5) and (6) of this section are:
(a)  Motor vehicles operated by the Idaho transportation department when used in the maintenance of the interstate or state highway system; and
(b)  The following:
(i)   Motor vehicles employed solely in transporting school children and teachers to or from school or to or from approved school activities, when the motor vehicle is either:
1.  Wholly owned and operated by such school; or
2.  Leased or contracted by such school and the motor vehicle is not used in furtherance of any other commercial enterprise;
(ii)  Motor vehicles controlled and operated by any farmer when used in the transportation of the farmer's farm equipment or in the transportation of supplies to the farmer's farm;
(iii) The transportation of agricultural products including fresh fruits and vegetables, livestock, livestock feed or manure at any time of the year;
(iv)  Motor propelled vehicles for the sole purpose of carrying United States mail or property belonging to the United States;
(v)   Motor carriers transporting products of the forest at any time of the year, including chip trucks;
(vi)  Motor carriers transporting products of the mine including sand, gravel and aggregates thereof, excepting petroleum products; and
(vii) Vehicles properly equipped, designed and customarily used for the transportation of disabled or abandoned vehicles by means of a crane, hoist, tow bar, dolly or roll bed, commonly known as a "wrecker truck" or "tow truck."

Thank you for any input.

Dale A Tabat
Truck Freight Program and Policy Manager
Washington State Departemnt of Transportation
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