​​​Oversize/Overweight Permit Harmonization

At its 2012 Annual Meeting in Pittsburgh, Pennsylvania, the AASHTO Board of Directors officially inaugurated an initiative begun by the Subcommittee on Highway Transport (SCOHT) known as "Harmonization," an effort among the 52 AASHTO member states to research and assess for common, minimum standards across the nation on oversize & overweight truck travel permits.

In order to facilitate this research, AASHTO first came to consensus on certain categorical permit items to be reviewed, known as Phase I (PR-3-12)

With generous support from the FHWA Office of Freight Operations, AASHTO selected a research team from Cambridge Systematics to facilitate research on the national, regional, and state-by-state impacts of oversize and overweight permit harmonization proposals selected in Phase I.


The freight transportation industry is a multi-billion dollar enterprise fundamental to the global economic competitiveness of the United States.  Trucks moving and delivering commercial goods on Interstates and state highways represent a significant amount of total freight volume in the U.S.  As the economy and industry evolves - especially in dynamic sectors such as energy exploration - trucks must often carry goods that make their dimensions higher, wider, and longer than current legal limits.

So that these trucks can safely and efficiently deliver their goods, State DOT's ensure safe highway routes, facilities, and escorts are used by these trucks through the issuance of oversize and overweight permits. 

Because highway conditions, traffic, and other variables are different and dynamic from state to state, these specialized trucks often encounter situations where compliance standards differ across states and thus require truck configuration changes or less efficient routes to complete interstate travel.

Industry Advisory Group
Working closely with industry leaders in operations, safety and policy, SCOHT has convened an Industry Advisory Group to assess the various impacts and efforts of permit harmonization.  Industry Advisory Group members include:

  • ​Steven Todd, Specialized Carriers and Rigging Association
  • Rick Clasby, Utah Trucking Association on behalf of the American Trucking Associations
  • Capt. Jay Thompson, Arkansas Highway Police on behalf of the Commercial Vehicle Safety Alliance
  • Jay Folladori, Bennett Motor Express LLC
  • Paul Ross, Keen Transport, Inc.
  • Ray Morgan, Perkins Specialized Transportation Contracting
  • Peter Lynch, Specialized Freight Solutions
  • Mike Morgan, National Pilot Car Association


AASHTO and SCOHT seek to enhance interstate commerce while maintaining highway safety by considering data driven proposals that may assist State DOT's in assessing legislative, regulatory, or policy changes that could remove certain barriers to interstate commerce that exist today. 

All proposals assume a minimum standard.  States that already meet or have less restrictive standards would achieve permit harmonization by simply retaining the status quo. 

States with more restrictive standards, but who would like to consider changes, may find the research and proposal recommendations a useful analysis tool that reflects the consensus view and best practices of many other States.  However, they should not consider this a mandate to make such changes. 

Final technical recommendations will be published in a revised edition of the AASHTO Guide to Vehicle Weights and Dimensions.

Phase I

The Phase I categories selected for research were:

  • Escort Requirements
  • Warning Flags
  • Warning Lights
  • Warning Signs
  • Days and Hours of Operation


SCOHT members, through the national subcommittee, as well as the 4 regional NASTO, SASHTO, MAASTO and WASHTO, continue to consider proposals for permit harmonization in these categories

Phase I Draft Findings Webinar

Analysis on Impact of Proposed Phase I minimum standards by State.  Maps and matrix representing whether or not States are currently harmonized by category.

Phase II

The AASHTO Board of Directors affirmed and continued its work on the permit harmonization effort at its 2013 Annual Meeting in Denver, Colorado by selecting additional categorical items for research (PR-13-13).  The items selected, known collectively as Phase II, include: 

  • Number of Valid days allowed on single trip permits
  • Permit Amendments
  • Holiday Restrictions
  • Type and Size of Escort Vehicles
  • Escort requirements for overheight loads and overheight loads with other dimensions

Research efforts on Phase II are currently underway.  SCOHT members are encouraged to complete a brief online survey to facilitate this effort.  Please click on the survey button below to begin.