What is a Lowboy Trailer?
A lowboy trailer (also called a low-bed or double-drop trailer) is a semi-trailer with the lowest deck height of any trailer type — just 18 to 24 inches above the ground. It is purpose-built for hauling tall, heavy equipment like excavators, bulldozers, cranes, and industrial machinery. The low deck height allows cargo to sit lower, providing more vertical clearance under bridges and overpasses while keeping the overall load height within legal limits. Lowboys come in two main configurations: fixed gooseneck (FGN) and removable gooseneck (RGN), each with different loading methods and weight capacities.
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5+ years dispatching heavy haul loads, coordinating lowboy shipments, and managing oversize permit logistics
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O TruckingWhat is a Lowboy Trailer? Definition & Heavy Haul Guide
What Is a Lowboy Trailer?
A lowboy trailer is a specialized semi-trailer designed to haul heavy, oversized equipment that cannot safely ride on a standard flatbed, step deck, or enclosed trailer. What sets the lowboy apart is its ultra-low deck height — typically 18 to 24 inches off the ground, compared to 48 to 60 inches on a standard flatbed.
The lowboy achieves this low profile through a “double drop” design. The trailer deck drops down from the gooseneck (the front section that connects to the tractor's fifth wheel), runs flat through a recessed well section, then rises back up over the rear axles. This creates a U-shaped profile that keeps the cargo's center of gravity as low as possible while maintaining enough ground clearance to travel on public roads.
The low deck height is not just about aesthetics — it solves a critical practical problem. Federal regulations limit overall vehicle height to 13 feet 6 inches in most states. When you are hauling a piece of equipment that is 10 feet tall, a standard flatbed (with a 5-foot deck height) would put your total height at 15 feet — nearly 2 feet over the legal limit. A lowboy with an 18-inch deck height brings that same load down to 11 feet 6 inches, well within legal limits and safely under most bridge clearances.
Lowboy trailers are the workhorses of the heavy haul industry. They move the equipment that builds highways, erects buildings, digs foundations, and powers infrastructure. If you see an excavator, bulldozer, or crane moving down the highway, it is almost certainly on a lowboy.
Common Lowboy Cargo
Construction Equipment
- Excavators (20-80 tons)
- Bulldozers (D4 through D11)
- Wheel loaders
- Motor graders
Cranes & Lifts
- Crawler cranes
- Rough terrain cranes
- Boom lifts
- Telescopic handlers
Industrial Equipment
- Transformers
- Large generators
- Industrial compressors
- Mining equipment
How a Lowboy Trailer Works
A lowboy trailer consists of three main sections: the gooseneck, the well (deck), and the rear axle assembly. Understanding how these work together helps you choose the right lowboy for your load and avoid costly mistakes during transport.
The Gooseneck
The gooseneck is the elevated front section that connects to the tractor's fifth wheel. It sits higher than the well section, creating the first “drop.” In a fixed gooseneck (FGN) trailer, this section is permanently welded to the deck. In a removable gooseneck (RGN) trailer, it can be detached hydraulically or mechanically, allowing the front of the deck to drop to ground level for drive-on loading.
The Well (Deck)
The well is the lowered, flat section between the gooseneck and the rear axles. This is where the cargo rides. Standard well lengths range from 24 to 30 feet on fixed gooseneck models and 29 to 53 feet on RGN models. The well sits 18 to 24 inches above the ground, giving cargo maximum height clearance. The deck surface is typically steel with tie-down points welded along the edges and floor for securing equipment.
The Rear Axle Assembly
The deck rises back up over the rear axles, creating the second “drop” in the double-drop design. The number of rear axles determines the trailer's legal weight capacity: 2-axle lowboys handle about 40,000 pounds, 3-axle models handle 60,000 pounds, and multi-axle configurations can handle 80,000 pounds or more. Some lowboys feature flip or removable axles that allow operators to add capacity when needed. See our weight capacity guide for detailed axle-weight breakdowns.
Why the Double-Drop Design Matters
Types of Lowboy Trailers
Lowboy trailers are categorized primarily by their gooseneck type. The gooseneck determines how equipment is loaded and unloaded, which directly impacts efficiency, cost, and the types of cargo the trailer can handle. For a deep dive into each type, see our complete types of lowboy trailers guide.
Fixed Gooseneck (FGN)
The gooseneck is permanently attached to the trailer frame. Equipment must be loaded from the side or rear using a crane, or driven up ramps placed against the rear of the trailer. FGN lowboys are less expensive to purchase and maintain because they have fewer moving parts. They are best for operations that have crane access at both pickup and delivery locations.
Hydraulic Removable Gooseneck (Hydraulic RGN)
The gooseneck detaches using hydraulic cylinders powered by the tractor's PTO or a dedicated hydraulic system. When detached, the front of the trailer drops to ground level, creating a ramp that equipment can drive directly onto. Hydraulic RGN trailers are the most popular type for heavy equipment because they eliminate the need for a crane at the loading site. They are more expensive to buy and maintain due to the hydraulic components.
Mechanical Removable Gooseneck (Mechanical RGN)
The gooseneck detaches using manual pins, latches, or mechanical linkages instead of hydraulics. This is a simpler and less expensive system than hydraulic RGN, but detaching and reattaching the gooseneck takes longer and requires more physical effort. Mechanical RGN trailers are less common today because hydraulic systems have become more affordable and reliable, but they are still used in operations where simplicity and lower maintenance costs are prioritized.
Hydraulic RGN Is the Most Versatile Choice
Lowboy Trailer Dimensions & Specifications
Knowing the exact dimensions of a lowboy trailer is critical for load planning. Even a few inches of miscalculation can mean the difference between a legal load and one that requires oversize permits. For comprehensive spec tables, see our complete lowboy trailer dimensions guide.
| Specification | FGN Lowboy | RGN Lowboy | Notes |
|---|---|---|---|
| Deck Height | 18-24" | 18-24" | Lowest of any trailer type |
| Well Length | 24-29 ft | 29-53 ft | RGN offers significantly more deck space |
| Overall Width | 8'6" | 8'6" | Standard legal width (wider needs permits) |
| Overall Length | 48-53 ft | 48-53 ft | Gooseneck to rear bumper |
| Max Cargo Height | Up to 11'6" | Up to 11'6" | Within 13'6" overall legal limit |
| Tare Weight | 15,000-20,000 lbs | 18,000-26,000 lbs | RGN is heavier due to detach mechanism |
Always Verify Specific Trailer Specs Before Loading
Weight Capacity by Axle Configuration
A lowboy's weight capacity is determined primarily by the number of axles on the trailer and the tractor. Federal bridge formula laws and state weight limits govern how much weight each axle group can carry. For a complete breakdown, see our lowboy trailer weight capacity guide.
| Axle Configuration | Payload Capacity | Max GVW | Typical Use |
|---|---|---|---|
| 2-Axle Lowboy | ~40,000 lbs | ~80,000 lbs | Mid-size excavators, skid steers, small cranes |
| 3-Axle Lowboy | ~60,000 lbs | ~100,000 lbs | Large excavators, bulldozers, wheel loaders |
| 4+ Axle (Multi-Axle) | ~80,000+ lbs | 120,000+ lbs | Crawler cranes, mining equipment, transformers |
These are approximate legal capacities without overweight permits. The exact capacity depends on the specific trailer model, tractor weight, axle spacing (which affects bridge formula compliance), and state-specific weight laws. Loads exceeding 80,000 pounds gross vehicle weight (GVW) always require overweight permits. Some states allow higher weights on certain highway systems with appropriate permits and axle configurations.
Overweight Permits Add Significant Cost
Loading & Securement
Properly loading and securing equipment on a lowboy trailer is one of the most safety-critical aspects of heavy hauling. An improperly secured 40,000-pound excavator that shifts during transport can cause a catastrophic accident. For a detailed loading procedure, see our how to load a lowboy trailer guide.
Drive-on loading (RGN only) — Detach the gooseneck and lower the front of the trailer to ground level. Drive equipment directly onto the deck from the front. This is the fastest and safest loading method for tracked and wheeled equipment. Re-attach the gooseneck after loading.
Crane loading — Use a crane to lift equipment onto the trailer deck. Required for FGN lowboys and for non-mobile equipment (transformers, generators, industrial machinery). Ensure the crane has sufficient capacity for the load weight plus rigging.
Ramp loading — Place ramps at the rear of the trailer and drive equipment up. This is less common on lowboys because the low deck height makes ramp angles manageable but the rear axle riser creates an obstacle. Works best with smaller equipment.
Securement Requirements
FMCSA cargo securement rules (49 CFR Part 393) require that equipment on a lowboy trailer be secured with enough tie-downs to prevent movement in all directions — forward, rearward, sideways, and vertically. The minimum requirement is based on the weight and length of the cargo:
- Under 5 feet long — Minimum 2 tie-downs
- 5 to 10 feet long — Minimum 2 tie-downs
- Over 10 feet long — Minimum 4 tie-downs, plus 1 additional for every 10 feet of length or fraction thereof
- Aggregate working load limit — Total tie-down capacity must equal at least 50% of the cargo weight
Most heavy equipment loads use grade 70 transport chains with load binders (ratchet or lever type). Chains are preferred over straps for heavy equipment because they are more resistant to abrasion from steel equipment surfaces and provide higher working load limits. Each 3/8-inch grade 70 chain has a working load limit of 6,600 pounds. A 40,000-pound piece of equipment requires a minimum of four chains with a combined working load limit of at least 20,000 pounds.
Lower Equipment Attachments Before Transport
Permits & Legal Requirements
One of the primary reasons to use a lowboy trailer is to keep loads within legal height limits. However, many lowboy loads still require special permits due to width, weight, or overhang beyond legal dimensions. Here is what you need to know:
| Dimension | Federal Legal Limit | When Permit Is Required |
|---|---|---|
| Height | 13'6" | Equipment + lowboy deck exceeds 13'6" overall height |
| Width | 8'6" | Equipment wider than the trailer deck (common with excavators) |
| Length | 53 ft (trailer) | Equipment overhangs beyond the trailer deck front or rear |
| Weight | 80,000 lbs GVW | Tractor + trailer + cargo exceeds 80,000 lbs gross |
Each state issues its own oversize and overweight permits independently. A load traveling from Texas to Ohio might need permits from Texas, Oklahoma, Missouri, Illinois, Indiana, and Ohio — six separate permits, each with its own application, fee, route requirements, and travel time restrictions. Many heavy haul carriers use permit services or in-house permit departments to manage this process.
Some states also require escort vehicles (pilot cars) for loads that exceed certain width or length thresholds. A common requirement is one pilot car for loads over 12 feet wide and two pilot cars for loads over 14 feet wide, but this varies by state. Pilot car costs typically run $500 to $1,500 per day per vehicle.
Lowboy vs Other Trailer Types
The lowboy is not always the right trailer for every load. Understanding how it compares to other trailer types helps you choose the most cost-effective option. For detailed comparisons, see our lowboy vs step deck guide and lowboy vs RGN guide.
| Feature | Lowboy | Step Deck | Standard Flatbed |
|---|---|---|---|
| Deck Height | 18-24" | 34-42" (lower deck) | 48-60" |
| Max Cargo Height | Up to 11'6" | Up to 10'2" | Up to 8'6" |
| Weight Capacity | 40,000-80,000 lbs | Up to 48,000 lbs | Up to 48,000 lbs |
| Best For | Heavy, tall equipment | Tall but lighter cargo | Standard freight, materials |
| Typical Rate/Mile | $3.50-8.00+ | $2.50-4.00 | $2.20-3.50 |
Lowboy Trucking Rates
Lowboy trucking rates are significantly higher than standard flatbed or dry van rates because of the specialized equipment, driver expertise, permit requirements, and higher insurance costs associated with heavy haul transport. For a comprehensive rate breakdown, see our lowboy trucking rates guide.
Typical Lowboy Rate Ranges (2026)
Standard Legal Loads
- Local (under 100 miles): $300-800 flat
- Short haul (100-300 miles): $3.50-5.00/mile
- Long haul (300+ miles): $3.00-4.50/mile
Oversize/Overweight Loads
- With permits: $5.00-8.00+/mile
- With escorts: Add $500-1,500/day per escort
- Superloads (200K+ lbs): Custom quotes only
Factors that affect lowboy trucking rates include:
- Load weight and dimensions — Heavier and wider loads cost more due to permit requirements and slower travel speeds
- Distance — Per-mile rates decrease on longer hauls because fixed costs (loading, permits) are spread over more miles
- Permit requirements — Each state permit adds cost, and multi-state routes can accumulate thousands in permit fees
- Escort vehicle requirements — Pilot cars add $500 to $1,500 per day per vehicle
- Seasonality — Construction season (spring through fall) drives higher demand and higher rates for lowboy transport
- Loading and unloading method — Crane fees at pickup or delivery add $500 to $3,000+ depending on crane size needed
How Our Dispatch Team Handles Heavy Haul
Heavy haul dispatching requires specialized expertise that goes beyond standard freight. At O Trucking LLC, our dispatch team manages the complexity of lowboy loads so our carriers can focus on driving safely:
Load dimension and weight verification
Before booking any heavy haul load, we verify the exact weight, dimensions, and specifications of the equipment being transported. We compare these against the lowboy trailer's rated capacity, deck dimensions, and tie-down configuration to ensure the load is both legal and safe. We do not book loads that push equipment beyond the trailer's rated limits.
Permit coordination across states
Multi-state oversize and overweight loads require permits from every state on the route. We coordinate permit applications, ensure routes comply with each state's bridge weight restrictions and travel time windows, and arrange escort vehicles when required. Our carriers receive a complete permit package and approved route before they leave the yard.
Rate negotiation for heavy haul loads
Heavy haul rates should reflect the full cost of the move — including permits, escorts, specialized equipment, and the higher risk involved. We negotiate rates that cover all costs and ensure our carriers are compensated fairly for the specialized service they provide. See our lowboy trucking rates guide for current rate benchmarks.
Related Resources
Step Deck Trailer
When a step deck is the better choice
Oversize Load
Permit requirements and regulations
Fifth Wheel
How the tractor-trailer connection works
Flatbed Dispatch Services
Our flatbed and heavy haul dispatch
Lowboy Trailer Guide Collection
Lowboy vs Step Deck
Which trailer do you need?
Dimensions & Specs
Well length, deck height & weight limits
Lowboy vs RGN
Fixed vs removable gooseneck
Types of Lowboys
FGN, hydraulic & mechanical detach
Weight Capacity
Legal limits by axle configuration
How to Load a Lowboy
Safety tips for heavy equipment
Lowboy Trucking Rates
What to expect for heavy haul
Lowboy Trailer FAQ
Common questions about lowboy trailers, dimensions, weight capacity, loading methods, and heavy haul transport
What is a lowboy trailer used for?
A lowboy trailer is used to transport tall, heavy equipment that would exceed legal height limits on a standard flatbed or step deck trailer. Common cargo includes excavators, bulldozers, wheel loaders, cranes, large generators, industrial transformers, and construction equipment. The lowboy's deck sits just 18 to 24 inches off the ground, which gives cargo up to 12 feet of total height clearance — compared to about 10 feet 2 inches on a step deck and 8 feet 6 inches on a standard flatbed. This makes the lowboy the trailer of choice whenever equipment is both heavy and tall.
What is the difference between a lowboy and a step deck trailer?
The main differences are deck height, weight capacity, and loading method. A lowboy deck sits 18 to 24 inches off the ground, while a step deck upper deck is 48 to 60 inches and the lower deck is 34 to 42 inches. Lowboys can haul 40,000 to 80,000 pounds depending on axle configuration, while most step decks max out at around 48,000 pounds. Lowboys typically require ramps or a crane for loading (unless using an RGN with detachable gooseneck), whereas step decks have built-in ramps. Step decks are more versatile for mixed freight; lowboys are purpose-built for heavy, oversized equipment.
How much weight can a lowboy trailer carry?
Weight capacity depends on the axle configuration. A standard 2-axle lowboy can carry approximately 40,000 pounds legally. A 3-axle lowboy increases capacity to about 60,000 pounds. Multi-axle lowboys (4 or more axles) with specialized configurations can haul up to 80,000 pounds or more, though loads above 80,000 pounds gross vehicle weight typically require overweight permits and escort vehicles. The trailer's own weight (tare weight) ranges from 15,000 to 26,000 pounds depending on the number of axles and trailer length, which reduces the net payload capacity.
What is the difference between a lowboy and an RGN trailer?
An RGN (removable gooseneck) is actually a type of lowboy trailer. The difference is in the gooseneck: a fixed gooseneck (FGN) lowboy has a permanently attached gooseneck, which means equipment must be loaded from the side using a crane or driven up ramps. An RGN lowboy has a detachable gooseneck that can be removed hydraulically or mechanically, allowing the front of the trailer to drop to the ground so equipment can be driven directly onto the deck from the front. RGN trailers typically have longer well lengths (29 to 53 feet vs 24 to 29 feet for FGN) and cost more to purchase and maintain.
What are the standard dimensions of a lowboy trailer?
Standard lowboy trailer dimensions are: deck height of 18 to 24 inches, well length of 24 to 30 feet (FGN) or 29 to 53 feet (RGN), overall width of 8 feet 6 inches (standard) or up to 10 feet with wide-load permits, and overall length of 48 to 53 feet from gooseneck to rear bumper. The well depth (the recessed section between the gooseneck and rear axles) is what creates the low deck height. Some lowboys have an adjustable ride height that lets operators raise or lower the deck for different loading scenarios.
Do you need a special permit to haul with a lowboy trailer?
Standard lowboy loads that stay within legal dimensions (8 feet 6 inches wide, 13 feet 6 inches tall, 80,000 pounds gross vehicle weight) do not require special permits in most states. However, many lowboy loads are oversize or overweight by nature — which is exactly why they are on a lowboy in the first place. If your load exceeds any legal dimension, you need an oversize or overweight permit from every state the load travels through. Some states also require escort vehicles, route surveys, and restricted travel times for oversized loads. Permit requirements and costs vary significantly by state.
How much does it cost to ship equipment on a lowboy trailer?
Lowboy trucking rates typically range from $3.50 to $8.00 or more per mile depending on the load weight, dimensions, distance, and whether permits or escorts are required. A standard 40,000-pound piece of equipment moving 500 miles might cost $2,500 to $4,000. An oversize or overweight load requiring permits, pilot cars, and route planning can cost $5,000 to $15,000 or more for the same distance. Factors that increase cost include multi-state permit requirements, bridge restrictions requiring route detours, time-of-day travel restrictions, and specialized rigging or crane services for loading and unloading.
Need Heavy Haul Dispatch for Lowboy Loads?
Our dispatch team specializes in flatbed and heavy haul freight. We handle load matching, permit coordination, broker verification, and rate negotiation so you can focus on the road.