The Office of Motor Vehicle Enforcement is responsible for monitoring and enforcement of truck weight regulations on roadways outside the project limits and on roadways within the project limits open to general traffic. Specification 1105.11 requires all hauling units delivering equipment or materials to the project to be legal weight loads and/or have appropriate hauling permits issued by the Motor Vehicle Division. The maximum allowable loads for various axle configurations are included in the Office of Motor Carrier Services’ publication, “Iowa Truck Information Guide” and can be viewed on their website at http://www.iowadot.gov/mvd/omve/truckguide.pdf.


            Hauling on Closed Roads

On projects closed to general traffic, if hauling of overweight axle loads on pavements and structures occurs, a non-compliance notice should be prepared. If overweight hauling continues, work on the project should be ordered to be suspended.


Hauling on Roads Open to General Traffic

On projects where overweight hauling occurs on roads open to general traffic, the contractor should be advised that if no action is taken to correct the loads, the Office of Motor Vehicle Enforcement will be notified of the problem. If overweight truckloads continue and the contractor does not correct the problem after being advised to do so, the project engineer should contact the Office of Motor Vehicle Enforcement.


Motor Vehicle Enforcement officers may be contacted at 515-237-3247.


Allowances to Axle Load Limits

·        Truck Hauling

Iowa Code 321.463 subsection 7 allows the weight on any one axle, including a tandem axle, to exceed the legal maximum weight by 10%, provided the allowable gross weight on any particular group of axles is not exceeded. This allowance applies only to material hauled from a borrow site to a construction project or material hauled from a construction project. In both instances, the hauling must be on the primary system or on an approved haul road. This allowance is not applicable to the interstate system.


·        Trucks with retractable axles

The use of trucks with retractable axles is common.  These additional axles allow increased hauling capacity when in the lowered position.  However, they must be raised to operate in reverse and to maneuver within the work zone.  For the purposes of enforcement of axle weight limitations, vehicles with retractable axles raised when operating on pavements between the Road Work Ahead and End Road Work signs on a construction project will be considered to be in compliance with 1105.11,  provided the vehicle is legal with the axles lowered when en route to the work zone. 


Unless otherwise approved by the Engineer, legal loads or restricted loads, as applicable for posted limits, will be required on bridgesThe allowance for retractable axles does not apply for operating on a bridge, even if it is within the construction project.  The operation of ready mix concrete trucks on bridges when the retractable axle is raised shall be submitted for review and approval as discussed on the following page.


·        Movement of Construction Equipment

Chapter 761 Section 511.12(5) IAC authorizes a higher axle limit for construction equipment based on the tire width. This allowance is intended only for moving of empty overweight equipment and not for hauling operations.


The administrative rule allows construction equipment with axle weights greater than 20,000, but less than 36,000 pounds, to operate on pavements for the purpose of moving the equipment. The allowable axle weight is increased 1,882 pounds for every inch of tire width over 18 inches wide, up to the maximum allowable axle weight of 36,000 pounds. This is allowed provided that the total gross weight is less than 80,000 pounds for movement under an annual permit and 126,000 pounds under a single or multi-trip permit.


The allowable axle weight is calculated using the formula:

      Legal axle load = 20,000 lbs. + {1,882 lbs. X (tire width - 18")}


Example: For a 23.5" X 25" tire


      Legal axle load = 20,000 lbs. + {1,882 lbs. X (23.5" - 18")} = 30,351 lbs.


      In this example, equipment with a 23.5" wide tire could be moved on pavement, provided that the actual axle weight did not exceed 30,351 pounds.


Equipment allowed by this rule may include small “paddle wheel scrapers” and small articulated dump trucks. Again, this allowance is intended only for moving of empty equipment.


·        Movement of Construction Equipment Across Bridges

Requests for crossing bridges with non-legal load equipment shall be submitted to the Office of Bridges & Structures – Bridge Rating Engineer for review and approval.  The request must be for empty equipment.


Iowa DOT Form 532011 Construction Equipment Input Data Sheet, in Appendix 3-9, shall be completed for all non-legal load construction equipment being requested to cross bridges.  Submittal of this form shall also include submission of a machine specification sheet with the dimensions and weights from the manufacturer to assist with the analysis. 


There are times on bridge projects where the contractor may have a need and make a request for operation of non-legal load equipment on a bridge.  The following are several forms that are available to provide the information that shall be submitted for these requests (which also shall include submission of a machine specification sheet with the dimensions and weights from the manufacturer to assist with the analysis):


Form 519323 “Track Crane Submittal – Request To Operate On A Bridge”


Form 519322 “Rubber Tired Crane Submittal – Request To Operate On A Bridge”


Form 519321 “Rubber Tired Concrete Pump Submittal -  Request To Operate On A Bridge”


Form 519320 “Ready Mix Concrete Truck Submittal - Request To Operate On A Bridge”