Over-dimensional (OD) freight is one of the most technically demanding areas of freight brokerage. The margin can be attractive, and shippers with heavy equipment, large fabrications, or industrial machinery need consistent coverage. But the compliance and coordination requirements are significantly higher than standard truckload. Brokers who enter OD work without understanding the mechanics get burned — often on their first large claim.
What Makes a Load Oversize or Overweight
Federal law establishes the baseline legal limits for vehicles operating on the Interstate Highway System:
| Dimension | Federal Legal Limit |
|---|---|
| Width | 8'6" (102 inches) |
| Height | 13'6" (162 inches) |
| Length | 53' for semi-trailer |
| Gross Vehicle Weight | 80,000 lbs |
| Single axle weight | 20,000 lbs |
| Tandem axle weight | 34,000 lbs |
Any load exceeding any of these limits requires a permit. A load can be legal on three dimensions and oversize on one — for example, a wide fabricated steel component that is within height, length, and weight limits but exceeds 8'6" in width. Each dimension is checked independently.
States have their own legal limits for state and US routes (as opposed to Interstates) that may differ from federal limits. Some states allow wider loads on certain routes without permits. Brokers operating in specific corridors regularly need to know state-specific rules.
The State-by-State Permit System
There is no federal OD permit. Each state issues its own permits, and a multi-state move requires a permit from every state the vehicle will travel through. A load moving from Texas to Ohio might require permits from Texas, Oklahoma (or Arkansas), Missouri, and Ohio — four separate applications, four separate fees, four separate sets of rules about operating windows, speeds, and escort requirements.
Permit procurement typically happens through one of two channels:
- In-house permit desk: Larger OD brokers and carriers have dedicated staff who handle permit applications for all states they operate in. This requires maintaining relationships with each state DOT, knowing each state's requirements, and having accounts set up for fee payment.
- Third-party permit services: Specialized companies handle multi-state permit procurement for a fee per state or per trip. They know each state's systems, requirements, and processing times. For brokers who do occasional OD work, outsourcing permit procurement to a specialist is often the right call.
Permit procurement time varies: some states offer same-day electronic permits for standard OD loads; others require 3–5 business days for review, especially for wide or heavy loads that require engineering review.
Route Surveys for Overheight Loads
Overheight loads — anything exceeding 13'6" — require a route survey before moving. The survey identifies potential clearance conflicts along the entire route:
- Bridge underclearances (highway overpasses, railroad bridges, utility lines)
- Traffic signal clearances
- Overhead utility lines (power, telephone, cable)
- Fuel canopy heights at planned fuel stops
Route surveys can be conducted by the carrier, a pilot car operator, or a specialized routing service. For very tall loads (16'+ or higher), the routing process can be extensive. Some states require permit applicants to submit route surveys as part of the permit application.
The broker's responsibility: verify that a route survey has been completed for any overheight load before the carrier departs. If the carrier takes a route not covered by the survey and strikes an overhead obstacle, the broker's failure to ensure proper routing can create liability exposure.
Escort Vehicle (Pilot Car) Requirements
Most states require escort vehicles (also called pilot cars) for loads that exceed certain width or length thresholds. The exact thresholds vary by state, but the common triggers are:
- Width exceeding 12'–14' (varies by state) typically triggers a front or rear escort
- Extreme widths (16'+) often require both front and rear escorts and sometimes law enforcement
- Very long loads with large overhang may require rear escorts
- Night-only movement windows for the widest loads
Escort drivers are licensed professionals in most states. They carry height poles (measuring clearances on overheight loads), safety flags, and communication equipment. They drive ahead of or behind the OD load, warn oncoming traffic, and communicate with the operator about obstacles.
Police escorts are required in some states for loads exceeding specific widths, typically 16' or wider, though some states have lower thresholds. Police escorts add cost and require advance coordination with local law enforcement — sometimes days in advance.
Forgetting to arrange required escorts is one of the most expensive mistakes in OD freight. A carrier who moves without a required escort is in violation of their permit — and so is anyone in the brokerage chain who facilitated the move without ensuring compliance.
Permit Windows and Time Restrictions
Permits are not open-ended. They specify:
- Route: The exact highways and roads the load must travel
- Valid dates: Permits expire; a permit issued for Monday through Wednesday cannot be used Thursday
- Time of day: Many states restrict wide loads to daylight hours only. Extremely wide loads may be restricted to specific overnight windows with low traffic
- Day of week restrictions: Some states prohibit OD moves on weekends or holidays
When a carrier misses their permit window — a common occurrence when pickups run late — they need a new permit before moving. Brokers who do not communicate permit window constraints to carriers and shippers will find their loads sitting because the carrier legally cannot move.
Understanding Superloads
A superload is a load that exceeds the maximum dimensions typically covered by standard OD permits — generally loads over approximately 200,000 lbs gross weight, or those exceeding 16' wide or 18'+ tall, though definitions vary by state. Superloads trigger a different level of regulatory scrutiny:
- Engineering analysis of bridges along the route to confirm they can bear the load
- Multi-agency coordination between multiple state DOTs and sometimes federal agencies
- Utility company involvement for power line lifts or removal along the route
- Extended permit timelines — weeks to months for very large superloads
Brokers should understand when a load crosses from standard OD territory into superload territory. Misclassifying a superload as a standard OD load — and pricing or planning accordingly — is a common and costly mistake.
Pricing OD Freight
OD freight pricing starts with the carrier's total cost, not the market rate for a standard TL move on the same lane.
Cost components to factor in:
| Cost Component | Notes |
|---|---|
| Base linehaul | Often priced per mile; lower speeds mean more driver hours |
| Permits | Per-state fees, plus permit service costs if outsourced |
| Escort vehicles | Per-escort, per-day or per-mile rates |
| Route survey | If required |
| Police escort | If required; rates vary |
| Slower transit speed | Wide/heavy loads have speed restrictions (often 55 mph or less) |
| Specialized equipment | Lowboys, extendable trailers, multi-axle configurations |
The carrier must quote you a number that covers all of these. Brokers who take a standard TL rate and add a small premium for "it's oversized" without understanding the actual cost components will find themselves in a loss position — or with a carrier who is cutting corners on permit compliance to preserve margin.
Frequently Asked Questions
Who is responsible for getting permits on an OD load — the broker or carrier?
Legally, the motor carrier is responsible for operating in compliance with state permit requirements. However, brokers who actively participate in permit procurement — or who represent to a carrier that permits are not required when they are — take on liability. Best practice: clarify in writing who is handling permit procurement, verify that permits have been obtained before the load moves, and keep records. Do not dispatch a load without confirming permits are in hand.
How long does permit procurement take?
It depends on the state and the load. Some states offer electronic same-day permits for standard OD loads. Others require 3–5 business days for standard reviews. Superloads requiring engineering analysis can take weeks or months. Always check permit timelines before committing to a pickup date with the shipper.
What is a pilot car and when is it required?
A pilot car (or escort vehicle) is a vehicle that travels ahead of or behind an OD load to warn traffic and check clearances. Requirements vary by state and load dimensions, but loads wider than approximately 12'–14' typically require at least one escort. Some states require police escorts for very wide loads. Pilot car operators are licensed in most states and familiar with the route and state requirements.
Can I broker OD loads without specialized equipment experience?
You can, but the learning curve is steep and the liability exposure for errors is high. Most brokers who successfully build OD practices either hire staff with permit experience, partner with permit services, or apprentice on OD operations with an established carrier before operating independently. Shipping a load without proper permits is a federal and state violation — the broker who facilitated the move is exposed.
What's the most common mistake brokers make on oversize loads?
Trusting shipper-provided dimensions without verification. Shippers sometimes measure incorrectly, omit attachments that add to load dimensions, or provide "approximate" measurements that turn out to be off. A load measured at 13'4" that is actually 13'8" requires different permits, possibly different routes, and potentially escorts that were not arranged. Verify dimensions independently. When in doubt, round up and permit for the larger dimension.