Confused about the Pennsylvania Department of Transportation’s (PennDOT) vehicle travel restrictions during bad weather? Here’s what you need to know.

During inclement weather events, PennDOT restricts vehicles by type in an effort to make roads safer and to prevent long-term road closures. The agency uses a Tier based system to determine which vehicles are allowed and which vehicles are banned from travel during a winter weather event.

The vehicle restrictions are issued by PennDOT in conjunction with the Pennsylvania State Police, and the Pennsylvania Emergency Management Agency as well as transportation officials in neighboring states.

To view PennDOT’s planned or active vehicle restrictions, take a look at the “Commercial Vehicle Restriction Info” on 511PA.com.

What Vehicles Types Are Included In PennDOT’s Vehicle Restriction Tiers?

Tier 1

Tractors without trailers

Tractors towing unloaded or lightly loaded enclosed trailers, open trailers, or tank trailers

NOTE: A lightly loaded CMV is defined as a vehicle that is less than 1/3rd of the GVWR (vehicle weight and cargo weight combined)

Tractors towing unloaded or lightly loaded tandem trailers

Enclosed cargo delivery trucks that meet the definition of a CMV

Passenger vehicles (cars, SUVs, pick-up trucks, etc.) towing trailers, to include:

Recreational travel trailers and fifth-wheel trailers

Enclosed cargo trailers

Open cargo trailers

Vehicle transport trailers

Recreational vehicles/motorhomes

School buses, commercial buses, and motor coaches without available chains or Alternate Traction Devices (ATDs)*

Motorcycles

Tier 2

Tier 1, plus the following:

CMVs towing loaded tandem trailers without chains or Alternate Traction Devices (ATDs)*

All school buses, commercial buses, and motor coaches regardless of the availability of chains or ATDs

Tier 3

Tier 1 and 2, plus the following:

All CMVs towing loaded tandem trailers regardless of the availability of chains or Alternate Traction Devices (ATDs).

All other loaded CMVs except for:

Those carrying full coverage tire chains for at least two drive wheels, or

Those with approved Alternate Traction Devices (ATDs)*

Tier 4

Tier 1, 2, and 3, plus the following:

All CMVs regardless of loading or availability of tire chains or approved Alternate Traction Devices (ATDs)

Referred to as a complete CMV restriction

Tier 5

Tier 1, 2, 3, and 4, plus the following:

All passenger vehicles

* Tire chains or ATDs do not need to be installed, but need to be readily available for use should the vehicle become stuck and not be able to move because of poor traction.

Most of the restrictions target CMVs because “CMV accidents typically involve longer closure times as specialized equipment is necessary to remove the CMVs and typically some additional hazmat cleanup is necessary due to the larger fuel tanks and larger engines requiring additional fluids to run these vehicles,” PennDOT says.

PennDOT may also issue speed limit reductions or restrict CMVs to the right lane when issuing weather-related vehicle travel restrictions.