SR-39: What You Need to Know About the 50-Foot Vehicle Restriction in Ogden Canyon

For decades, State Route 39 (SR-39) through Ogden Canyon has connected the Wasatch Front to the mountain recreation of the Ogden Valley. Whether heading up to Pineview Reservoir for a summer boat day or pulling a travel trailer to campgrounds in the area, the winding, five-mile corridor is a popular drive for locals and visitors alike.

However, the physical limitations of a narrow canyon road, combined with the growing number of oversized recreational and commercial vehicles led us to make some changes for safety.

We implemented a permanent restriction prohibiting  personal and commercial vehicle combinations  longer than 50 feet from traveling through Ogden Canyon.

Keep reading to learn why this restriction exists, how to measure your vehicle combination and which  alternate route to use.

The Science and Safety Behind the 50-Foot Cap

We restricted combined vehicle length to 50 feet based on engineering data and public safety concerns along SR-39.

Our engineers analyzed the corridor and used computer modeling to simulate how vehicles navigate the road’s tight turns.

The study focused on “The Narrows,” a tight stretch near the mouth of the canyon west of the Old Kiln, where rock walls jut toward the road. The findings revealed a physical limitation: it is impossible for any vehicle combination longer than 50 feet to navigate The Narrows without crossing the double yellow line and encroaching into oncoming traffic.

To address lane encroachment and enhance driver safety, we partnered with the Utah Highway Patrol (UHP) and the Weber County Sheriff’s Office to enforce the permanent 50-foot limit. Alongside the length cap, we reduced the speed limit in The Narrows to 35 mph, installed radar feedback signs, added centerline rumble strips, and upgraded safety barriers.

Are You Over 50 Feet? How to Measure Your Rig

Many people believe the length restriction applies only to commercial semitrucks; however, it applies to the total bumper-to-bumper length of any vehicle or vehicle combination. This means personal vehicles pulling boats, campers, or utility trailers must also follow the law.

How to Measure Your Vehicle Combination

Measure in a straight line from your vehicle’s front bumper to the back of your trailer or whatever you’re towing (including outdrives, swim platforms, and spare tires).

Common Setups That Exceed the 50-Foot Limit

Because vehicle dimensions and trailer tongue lengths vary significantly, total setup lengths can quickly add up.

Crew-Cab Pickups Towing Wakeboard or Ski Boats 

A standard four-door pickup truck measures around 19 to 20 feet. When paired with a 23-foot wake boat on a trailer (adding 4 to 5 feet for the trailer tongue and rear platform), the setup totals roughly 46 to 48 feet. However, longer crew-cab trucks with extended beds or larger 25+ foot boats can easily push the total setup over the 50-foot limit.

Full-Size Pickups Towing Travel Trailers

A half-ton or three-quarter-ton truck pulling a travel trailer longer than 25 feet will almost always exceed 50 feet.

Fifth-Wheels and Large Toy Haulers 

Combined truck and fifth-wheel setups may range  from 52 to more than 65 feet.

Class A & Class C Motorhomes Towing Vehicles

Even a moderate 32-foot motorhome flat-towing a small SUV exceeds 50 feet.

Commercial Haulers and Flatbeds 

Semis, dump trucks towing equipment, and large commercial box trucks.

Alternative Route to the Ogden Valley

Vehicles and vehicle combinations longer than 50 feet are prohibited in Ogden Canyon and must use an alternate route.

Use the following alternate to reach Ogden Valley:

I-15 → I-84 Weber Canyon → Exit 92: Mountain Green→ SR-167 Trappers Loop → Ogden Valley / Huntsville / Pineview

The Designated Route: Interstate 84 (I-84) to State Route 167 (SR-167)

Take Interstate 84 (I-84) eastbound through Weber Canyon to Exit 92 at Mountain Green, then take State Route 167 (SR-167) Trappers Loop Road north into Ogden Valley.

Trappers Loop is able to accommodate large vehicles including semitrucks,  RVs, and boat trailers. It features more lanes, wide shoulders, broad turning radii, and clear sightlines, making it a smoother and less stressful drive.

Route to avoid: The North Ogden Divide

Please avoid the North Ogden Divide as an alternative route.

While it appears on maps as a shortcut over the mountain from North Ogden to Liberty, this county road is narrower and more challenging than Ogden Canyon. It features steep grades, switchbacks, sheer drop-offs, and rockfall risks, making it unsuitable for large trailers or wide loads.

Tips for a Smooth Trip

Measure Before You Hit the Road

Measure your setup’s length instead of guessing. Grab a tape measure and know your numbers before hitching up on a busy weekend morning.

Use the Alternate if You’re Longer than 50 feet

Take I-84 through Weber Canyon to SR-167/Trappers Loop instead of traveling through Ogden Canyon.

Check the UDOT Traffic App 

Before entering the canyon, check the UDOT Traffic App or our road information page for real-time traffic, construction delays, or emergency closures.

Planning ahead, measuring your vehicle or vehicle combination, and using I-84  through Weber Canyon to Trappers Loop if it is longer than 50 feet helps keep the road safe for everyone heading up to enjoy Ogden Valley!