Agricultural Equipment on Public Roads – What are the Impacts

The size and weight of agricultural equipment and the potential impact it has on public roads is the subject of a series of town hall meetings to be held throughout the state this month.  It is important at this time to have agricultural interests represented at these meetings as well as other local road users and authorities.

The Wisconsin Department of Transportation (WisDOT) and Department of Agriculture, Trade and Consumer Protection (DATCP) are urging the agricultural community, local highway officials and others to attend the meetings. Sessions will provide detailed information on the recommendations of a special study group that reviewed size and weight limits and other issues related to agricultural equipment, also known as implements of husbandry (IoH).

Agricultural equipment is getting larger and heavier which helps in more efficient farm production, but it can also impact pavement and road structures. That’s why WisDOT, in partnership with DATCP, convened the IoH Study Group. It involved over 20 stakeholders representing various transportation and farm organizations, equipment manufacturers, law enforcement, local officials and the University of Wisconsin-Madison/Extension.  Cheryl Skjolaas, Interim Director and Agricultural Safety Specialist, UW-Madison/Extension Center for Agricultural Safety and Health has been a member of this Study Group and co-chairs the Education and Outreach Workgroup.

“We recognize that agriculture is a vital element of our state’s economy, but there are limits for our roadway infrastructure that are defined by physics and safety,” says Rory Rhinesmith, deputy administrator of WisDOT’s Division of Transportation System Development and chair of the study group.“IoH equipment can’t exceed the capacity of our roads and bridges and must be able to safely operate with other road users. Our approach was to bring together a knowledgeable group of people committed to finding a balanced solution based on science and the needs of the agricultural community.”

“DATCP was pleased to partner with WisDOT on this effort. I hope farmers and other citizens will attend the town hall meetings to get a better understanding of the recommendations,” says Jeff Lyon, DATCP deputy secretary. “The group came up with several options that could lessen the impact on our roads.

Obviously, there needs to be a balance between the needs of farming and other road users.”

Study Group Phase 2 Report

The complete IoH Study Group report is at , see Phase 2 Report. Two of the more challenging issues for the study group were establishing maximum size and gross vehicle and axle weight limits. Safety, the capacity of roads and bridges and consideration of commonly used IOH equipment guided the recommendations for size. Road width, overhead wires, bridge standards and the ability to safely maneuver through turns determined the new size parameters. The recommendation on weight allowance is based on engineering analysis and research on the damage done to roads as a result of increased weight. Data from the MnDOT Road Study funded in part by PNAAW was used in the engineering analysis.

Overview:  Draft recommendations and overview of the Phase 2 Report as of August 5, 2013:

  • Clarify IoH Definition:
    • Create a clearer, simpler definition of Implements of Husbandry (IoH) to reflect today’s agricultural equipment.
      • Commercial Motor Vehicles (CMV) used exclusively for agricultural operations are defined as an IoH CMV.
      • All IOH will be exempt from registration.
      • A self-certification will be available for IoH CMVs.
    • Create size limits or an “envelope” for IoH:
      • Width envelope:
        • Width of IoH – 15’ (feet); However, an IoH greater than 15’ (feet), but no greater than 17’ (feet) may be operated without written authorization when the IoH operator meets safety requirements to ensure safe passage by other road users.
        • Width of IoH CMV – 10’ (feet)
      • Height envelope:  Height of IoH – 13’6” (feet/inches). An IoH greater than 13’6” (feet/inches) may be operated without written authorization. The IoH operator is responsible for ensuring safe clearance of any overhead obstructions.
      • Length envelope:  60’ (feet) for a single IoH; 100’ (feet) for combinations of two IoH; and 70’ (feet) for combinations of three IoH.
    • IoH is given an expanded 15% weight allowance over the limits as established by the Federal Bridge Formula, except where posted and during periods of spring thaw. This equates to a maximum single axle weight of 23,000 pounds and a gross vehicle weight of 92,000 pounds. A new IoH weight table will be created to (e.g. 348.30 reflect the 15% allowance based on gross vehicle weight, axle weight and spacing.
    • Written authorization to exceed the size envelope and weight limits may be requested on an annual basis from the maintaining authority of that roadway. Written authorizations may only be granted when:
      • The operator is 18 years of age and holds a valid driver’s license.
      • IoH meets lighting, marking, and safety requirements pertaining to IoH in s. 347 (safety requirements).
      • A travel or route plan for the IoH is submitted.
      • Additional conditions may be set by each maintaining authority (local or state) of which the IoH is operating within the context of the written authorization.
  • IoH vehicles operating in excess of the 15% allowance will be fined for the amount in excess of standard gross motor vehicle weight or individual axle weight.
  • Support exploration of best practices to assist in reducing the wear of roadways and structures.  This includes supporting the development of emerging innovations and best practices in manure management.
  • Develop a self-certification system for IoH CMVs rather than a plate, sticker, or decal.

Meeting Dates and Locations

The town hall meetings will offer a chance to ask questions and provide feedback on the proposed size and weight limits. In addition, the meetings will share other recommendations such as new definitions for IoH, operator requirements for vehicles that exceed base definitions and best practices such as pipelines, nurse trucks and one-way roads. Information collected at meetings and during the comment period (August 14-September 6) with compiled as an addendum to the Phase 2 Report and shared with the IOH Study Group as well as legislative interests.

All of the meetings, co-hosted by the University of Wisconsin Extension, will take place from 7:00 to 8:30 p.m. on the dates and locations listed below:

  •  August 19 – UW Extension Office, 5201 Fen Oak Drive, Madison
  •  August 20 – Country Aire Banquet Hall, F1312 County Road P, Stratford
  •  August 28 – Cashton Community Hall, 8111 Main Street, Cashton
  • August 29 – WisDOT US 41 Brown County Field Office, 1940 West Mason Street, Green Bay (NOTE: Building is behind Pizza Hut at the corner of Taylor and West Mason Street.)
  •  September 3 – Chippewa County Courthouse Large Assembly Room, 711 North Bridge Street, Chippewa Falls

The meeting sites are accessible to wheelchairs. Citizens who are deaf or hard of hearing and require an interpreter should call WisDOT (608) 267-7111 at least three working days prior to the meeting.

 Providing Comment If Unable to Attend a Meeting

If you are unable to attend the meeting and would like more information or to comment, contact Rory Rhinesmith, Deputy Administrator, Division of Transportation System Development at (608) 267-7111. Written comments regarding the project can be mailed to Mr. Rhinesmith, WisDOT, 4802 Sheboygan Avenue, Room 451, PO Box 7910, Madison, WI 53707-7910 or submitted via email to

Questions or Comment

Cheryl Skjolaas, as a member of the Study Group, would be willing to answer your questions or receive comments too. You may contact Cheryl by completing the contact info below.


Sharing is Caring - Click Below to Share
University of Wisconsin-Extension