I've been trying to figure this out and haven't been able to. Occasionally (more like every week right now), PennDOT decides to lower the speed limit on certain highways to 45 MPH during winter weather. I question how enforceable this is.
The ways in which motorists are informed are varied and inconsistent. One time last year I saw the message on a digital sign. This year, I've heard about it mostly on the radio and TV. When I was getting on the Turnpike last week, there was a flashing sign on 283 that told me to tune to AM 1600 something and the message was there, but there was another identical sign on the actual Turnpike that wasn't flashing. Even so, I don't believe that Pennsylvania requires vehicles to have working radios, you're not legally required to listen to those stations, and I'm pretty sure that deaf people are allowed to drive, so I don't see how that can be enforceable.
I believe that PennDOT is allowed to lower the speed limit under the provisions of this section:
There is no requirement for exactly how these limits are to be posted. This raises questions since the section covering normal speed limits does:§ 3363. Alteration of maximum limits.
On highways under their respective jurisdictions, local
authorities subject to section 6109(e) (relating to specific
powers of department and local authorities) or the department,
upon the basis of an engineering and traffic investigation, may
determine that the maximum speed permitted under this subchapter
is greater or less than is reasonable and safe under the
conditions found to exist upon any such highway or part thereof
and establish a reasonable and safe maximum limit. The maximum
speed limit may be made effective at all times or at times
indicated and may vary for different weather conditions and
other factors bearing on safe speeds.
So I have two questions. Is anybody aware of any cases of winter speed limits being enforced, and is there some other law that describes how temporary speed limits are required to be posted to be enforceable?§ 3362. Maximum speed limits.
(a) General rule.--Except when a special hazard exists that
requires lower speed for compliance with section 3361 (relating
to driving vehicle at safe speed), the limits specified in this
section or established under this subchapter shall be maximum
lawful speeds and no person shall drive a vehicle at a speed in
excess of the following maximum limits:
(1) 35 miles per hour in any urban district.
(1.1) 65 miles per hour for all vehicles on freeways
where the department has posted a 65-miles-per-hour speed
(1.2) 25 miles per hour in a residence district if the
(i) is not a numbered traffic route; and
(ii) is functionally classified by the department as
a local highway.
(2) 55 miles per hour in other locations.
(3) Any other maximum speed limit established under this
(b) Posting of speed limit.--
(1) No maximum speed limit established under subsection
(a)(1), (1.2) or (3) shall be effective unless posted on
fixed or variable official traffic-control devices erected in
accordance with regulations adopted by the department which
regulations shall require posting at the beginning and end of
each speed zone and at intervals not greater than one-half
(2) No maximum speed limit established under subsection
(a)(1.1) shall be effective unless posted on fixed or
variable official traffic-control devices erected after each
interchange on the portion of highway on which the speed
limit is in effect and wherever else the department shall
The only reason I'm so worried about it is because, in the government's grand tradition of nannying, these limits are usually applied to more miles of road and for more hours than is necessary. Last week I was driving on a bone dry road with a 45 MPH limit because part of it a hundreds miles away was under the weather.