Heavy Haul

Heavy haul services are essential when equipment or materials exceed the legal size and weight limits for standard highway transport. From turbine components and transformer banks to industrial presses and prefabricated building modules, heavy haul requires specialized trailers, DOT-compliant permitting, and meticulous route planning. All heavy haul operations in our network comply with federal regulations under 23 CFR Part 658 and FMCSA (Federal Motor Carrier Safety Administration) requirements under 49 CFR Parts 385-399.

What Makes Heavy Haul Different

Standard freight moves within established weight and dimensional envelopes. Heavy haul operates outside those envelopes, which triggers an entirely different regulatory and operational framework. The Federal Bridge Formula (23 CFR 658.17) governs how weight must be distributed across axles to protect bridge infrastructure, and exceeding its limits requires engineering analysis of every bridge on the route. FHWA’s Oversize/Overweight Load Permit Procedures guide states in establishing their individual permitting programs, resulting in a patchwork of requirements that must be navigated for every multi-state move.

Our network includes heavy haul carriers who specialize in this complexity. They operate equipment purpose-built for oversize transport: multi-axle lowboy trailers, hydraulic platform trailers (HPTs), extendable stretch trailers, Goldhofer modular trailers, and self-propelled modular transporters (SPMTs) for the heaviest and most dimensionally challenging loads.

Equipment and Capabilities

The right trailer selection is critical to a safe and compliant heavy haul. Key equipment types include:

• Multi-axle lowboys — Low-deck trailers rated from 35 to 80+ tons, used for construction equipment, industrial machinery, and fabricated structures. Deck heights as low as 18 inches maximize overhead clearance on routes with bridge restrictions.
• SPMTs (Self-Propelled Modular Transporters) — Computer-controlled platform transporters that can be combined in arrays to carry loads exceeding 10,000 tons. Each SPMT module has independently controlled axle lines with hydraulic suspension for precise load leveling during transport.
• Hydraulic platform trailers — Multi-axle trailers with hydraulic steering and suspension, capable of distributing extreme loads across dozens of axle lines to comply with the Federal Bridge Formula and state weight-per-axle limits.
• Stretch and extendable trailers — Adjustable-length trailers for loads that exceed standard 48-foot length limits, such as bridge beams, wind turbine blades, and long structural steel members.

Permitting and Route Planning

Every heavy haul move on public roads requires oversize/overweight permits from each state the route crosses. The permitting process involves:

• Route surveys with measurements of bridge capacities, overhead clearances, turning radii at intersections, and road surface conditions. The FHWA requires that states analyze bridge loading for permits exceeding standard legal limits, referencing AASHTO (American Association of State Highway and Transportation Officials) bridge rating procedures.
• State permit applications specifying exact load dimensions, gross weight, axle configurations, and requested travel dates. Many states restrict oversize movements to daylight hours and prohibit travel on certain holidays and weekends.
• Escort and pilot car coordination as required by state law. Most states require at least one escort vehicle for loads exceeding certain width or length thresholds, with additional escorts for superloads or routes involving lane closures.
• Utility coordination for loads tall enough to require temporary power line lifts or traffic signal removal, coordinated with local utility providers and municipalities.

Regulatory Framework

Heavy haul transport is governed by a layered set of federal and state regulations:

• 23 CFR Part 658 — Federal size and weight limits for commercial vehicles on the National Network, including the Federal Bridge Formula for axle weight distribution
• 49 CFR Parts 385-399 (FMCSA) — Federal motor carrier safety regulations covering driver qualifications, hours of service, vehicle maintenance, and cargo securement (49 CFR 393 Subpart I)
• FHWA Comprehensive Truck Size and Weight Study — Federal guidance that informs state permitting policies for oversize/overweight loads
• AASHTO bridge rating standards — Engineering procedures used by state DOTs to evaluate whether permitted loads can safely cross specific bridge structures

Contractors in the Specialized Carriers & Rigging Association (SC&RA), an international trade association of more than 1,400 members across 46 countries, follow industry best practices for heavy haul transport and maintain the specialized insurance, safety programs, and equipment certifications required for oversize and overweight operations.

Our Contractor Network

We match you with heavy haul carriers who have direct experience with your load type, route complexity, and permit requirements. Every carrier in our network maintains FMCSA operating authority, proper cargo and liability insurance, and demonstrated expertise in oversize/overweight transport. Whether your project needs a single lowboy move across town or a multi-state SPMT transport of a 500-ton reactor vessel, we connect you with the right equipment and crew.