REDMOND — Engineers in neon vests and Oregon Department of Transportation workers lined the inside of the faux roundabout made of cones and sandbags, watching as a truck labeled “oversized” made its way through the course, skillfully — although narrowly — missing the cones.

It was one of nine trucks, some measuring more than 200 feet long, that would give the roundabout a practice run to test the design for a roundabout being installed between Redmond and Prineville at the intersection of state Highway 126 and Tom McCall Road.

According to Mike Darling, senior project manager for ODOT, the purpose of the “roundabout rodeo” was twofold: first, to give local freight truck companies and drivers peace of mind knowing their routes would not be negatively affected by the roundabout and, second, to observe how the trucks fit through it to make any tweaks in design necessary to ease the trip. The test was staged at the Deschutes County Fair & Expo Center.

“We’ve done a lot of outreach and involvement and discussion with the freight community,” Darling said. “We want to figure out how to get freight through a roundabout in a way that they feel comfortable with and in an efficient and safe manner.”

ODOT, the city of Prineville and Crook County are working together on the project — Prineville’s first roundabout — after recognizing that a significant number of crashes occur at the intersection. High speed of traffic and stop signs placed only on Tom McCall Road contribute to the danger, and with growing industrialization of the area, organizers anticipate an increased number of drivers on the road.

At a public hearing in Prineville earlier this month, ODOT traffic standards engineer Kevin Haas said the agency expects a 70 percent reduction in total crashes at the intersection after the installation of the roundabout, and an 89 percent reduction in fatality or injury crashes. This is a greater reduction than would be expected if a signal were installed there.

The roundabout is also expected to be less expensive and to cause less of a slowdown in traffic with its “rolling queue” than with a traditional signaled intersection. Construction is anticipated to cost $3.5 million.

At the test, engineers measured the size of trucks and their axles, mounted cameras on them to watch the trucks’ paths and observed how the trucks maneuvered through the roundabout, marking where they went over the mountable curb (the slanted sides of the center median).

“So far, it works,” Darling said Thursday morning. “The truck drivers have been pleased so far.”

Darling said that while the size of the roundabout, set to have a 175-foot inner circumference, likely won’t change much, Thursday’s findings might lead to small tweaks in the design of the approaches and angles of the turns.

Once the design is finalized and approved by the city of Prineville, construction is expected to begin in 2018.

— Reporter: 541-633-2108,

cduffy@bendbulletin.com