ST. GEORGE — Oversized vehicles will soon face limitations on the Zion-Mt. Carmel Highway, which winds through Zion National Park.
In mid-2026, oversized vehicles can enter the park but drivers may have to go around the park, instead of straight through it. This will help reduce the likelihood of collisions on the highway as new safety measures will be implemented, according to a news release.
“These changes reflect months of discussions to find the best way forward to manage the historic Zion-Mt. Carmel Highway and increase driver safety,” said Jeff Bradybaugh, Zion National Park superintendent, in a news release. “Our goal is to protect drivers, meet modern safety standards and ensure the integrity of the road and tunnels so that we continue to enjoy scenic drives on the historic Zion-Mt. Carmel Highway.”
Vehicles will be rerouted if they exceed 50,000 pounds or 11 feet, 4 inches in height, 7 feet, 10 inches in width and 35 feet, 9 inches in length.
This move reflects recent discussions with the park’s neighbors, transportation departments, elected officials and businesses. The park will increase safety measures in the next few years, and these changes aim to help reduce the following:
- Collision likelihood.
- Overweight transits on road bridges.
- Lane-crossing due to vehicles being too long to negotiate turns.
Vehicles exceeding specifications can still enter the park and be on open roads. If they are too large to operate safely on the Zion-Mt. Carmel Highway, however, their drivers can travel around the park on other existing roads.
Zion National Park Communications Specialist Ally O’Rullian told St. George News that travel times depend on where a visitor is coming from, and where they want to go. For example, Bryce Canyon Visitor Center to Zion Canyon Visitor Center through South Entrance via Highway 20 is 63 miles or 42 minutes longer. O’Rullian said the North Rim Visitor Center to Zion Canyon Visitor Center through South Entrance via Highway 59/389 is 23 miles or 10 minutes longer.
Changes to the Zion Mt. Carmel will have the greatest effect on traffic flow at the tunnel. O’Rullian said data from the summer of 2023 shows that nearly 50 tunnel escorts occur every day, which blocks traffic on one side of the tunnel to accommodate larger vehicles.
“This can lead to highly congested traffic near both sides of the tunnel entrance, where we’ve had reports of people waiting up to an hour to drive through,” O’Rullian said.
She added that the visitors’ experience will improve due to the reduced oversized vehicles on the road.
O’Rullian added that in discussing potential operational changes, the park determined that expanding the historic road is not feasible because of the terrain.
“New construction would be prohibitively expensive and would significantly impact the park’s landscapes, plants, animals and affect the historic values of the road itself,” O’Rullian said. “The operational changes the park is proposing relate to large vehicles only and aim to take care of this historic road and its historic bridges and reduce the likelihood of collisions for all visitors.
Engineering and traffic studies of the current road use found that many large vehicles present public safety concerns. Studies found that recreational vehicles or motor coach buses cross the centerline in 18 locations where the road’s turning radius cannot accommodate long vehicles. This becomes problematic when vehicle length exceeds 35 feet, 9 inches. Bridges on the Zion-Mt. Carmel Highway are rated for 50,000-pound vehicles, but some large vehicles exceed this weight.
Additionally, the Zion-Mt. Carmel Tunnel has its own restrictions. Vehicles wider than 7 feet, 10 inches and taller than 11 feet, 4 inches cannot pass through the tunnel while maintaining two-way traffic and require a tunnel escort. Vehicles taller than 13 feet, 1 inch cannot fit through the tunnel and are not allowed.
The Zion-Mt. Carmel Highway has the following challenges:
- Tight turns.
- Some steep grades.
- A large number of switchbacks.
- Relatively narrow lanes.
- Two low and narrow tunnels.
- Bridges.
O’Rullian said these design elements make the road more compatible with the landscape, making it difficult for modern, larger vehicles to travel safely. When the road was designed, vehicles were smaller, moved slower and weighed much less.
Park officials said expanding the historic road is not feasible because of the terrain. New construction could be prohibitively expensive, harm the park’s landscapes, plants, and animals, and impact the road’s historic values.
“To reduce the likelihood of collisions and fulfill our responsibility to take care of this historic road, Zion intends to reroute large vehicle traffic in mid-2026 to help ensure visitor safety, improve driving conditions, and reduce the likelihood of structural damage,” the news release stated.
The tunnel and highway were dedicated on July 4, 1930. They linked Zion Canyon to the land east of the park and made it easier to visit the Grand Canyon and Bryce Canyon national parks.
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