How UDOT ensures you can safely drive under these natural arches near Bryce Canyon after 100 years

PANGUITCH, Utah (ABC4) — The Red Canyon Arches were recognized 100 years ago, in 1925, as the “original entrance to Utah National Park,” the Utah Department of Transportation (UDOT) says. Not only is Utah National Park now known as Bryce Canyon National Park, but everything around has changed, with the arches over SR-12 remaining the one constant.

“These are beautiful natural arches, they’ve been around for a long time — I wish we knew exactly when — but a long time. They are iconic to the point that you see them in tourism brochures across the country for Utah,” James Corney, UDOT Structures Project Engineer, said.

UDOT has been working to ensure that drivers can continue to experience the Red Canyon Arches and drive under them. In 2019, phase one of a project to understand the arches began. Drones, sensors and a stationary LiDAR tool were used to collect data on these iconic arches. The arches had sustained some damage, and UDOT wanted to keep them standing.

“Because they are old and natural, they are kind of not ‘constructed,’ maybe, to modern standards for bridges and tunnels… so you have a little bit of a narrow space, it’s kind of constricted,” Corney explained. “If you have large vehicles passing through, sometimes they hit and scrape and they do bad things.”

UDOT is currently in a “monitoring phase,” according to Corney. The drone collected thousands of photos that were turned into a 3D recreation of the arches, while the LiDAR tool used laser beams to “scan through and underneath the arches,” according to UDOT. This data is used to monitor and track rockfall, displacement, deformations in the arches and any other concerns.

“We’ve recently gone through and repaired the arches from a hit that happened a couple of years ago. And it scraped some of the protective concrete coating that we have on the inside of the arches off,” Corney said.

Shotcrete, a concrete mix, is sprayed onto the arches’ natural rock to strengthen and preserve them, UDOT says. In 2019, a “larger collision” and other smaller incidents caused “increased damage” to the arches. This began the project to monitor the arches more closely, a change from previous biennial assessments.

This spring, additional funding was secured to support phase two of the project. Using the data collected previously, crews will be installing additional sensors at “crucial locations” in the arches. Some of the sensors that were installed previously are damaged or are not providing enough data.

“So we come in and we’re putting sensors on them to just monitor them as they expand and contract through the seasons, as things get hot and cold, make sure that things are staying where we want them to be,” Corney shared. “We have geologists and geophysicists come out and actually take a real detailed look at the rock structure.”

Corney said that during monitoring, changes can be seen slowly over the span of several months. He emphasized that monitoring these structures is important not only because of human-caused damage, but also natural forces like erosion.

“We really don’t want to have a situation where these structures lose their natural beauty, we want them to stay where they’re at, looking good for a long, long time,” Corney shared.

UDOT says that they are planning to install the new sensors this fall, after the tourism season and tourist traffic have slowed down.