Coralville council approves city’s first ‘mini-roundabout’

CORALVILLE - In a few months, area drivers will have a new, yet slightly different, roundabout to navigate in Coralville.

The Coralville City Council on Tuesday approved awarding the $139,000 construction contract for Coralville's first mini roundabout, to be built at the intersection of 12th Avenue and Holiday Road, to J & L Construction, out of Washington, IA.

Scott Larson, Coralville assistant city engineer, said the mini roundabout is exactly what it sounds like, except of course that it's smaller, which was a decision based largely on the location, Larson said.

Due to the limited space at the intersection and that a full-sized roundabout would have required reconstruction of the nearby bridge, Larson said staff opted to design a smaller roundabout, with the most noticeable difference being that instead of a prominent central island as included in larger designs, the mini roundabout's center will include a curb with pavers, to allow for large vehicles like buses or trucks to navigate the circle.

This option also includes a considerable cost savings, Larson added.

'You could easily envision a $2 million project or more if we wanted to do the ultimate roundabout in that particular location,” he said. 'It's just not the time to tackle that.”

That said, the busy construction climate, as well as the hope of having the project finished this by July 1, brought higher bids than anticipated - the approved contract of the lowest bid for about $139,000 was almost 34 percent above the engineer's estimate for the project.

'It's a pretty condensed construction schedule,” Larson said. 'We kind of understand where the numbers came in a little bit higher than we would have wanted.”

Larson said the mini roundabout is expected to be finished before the roundabout being constructed at Oakdale Boulevard and Jones Boulevard.

Another roundabout could be considered in coming years at the intersection of Fifth Street and 10th Avenue.

Larson said city staff still lean more toward full-sized roundabouts, but said the mini roundabout design could be used again.

'I think our general preference would be to do a normal sized roundabout where we could. So I think were interested to see how this works and if it works, we could add it to our toolbox so to speak,” he said.

A roundabout is a traffic circle that flows vehicles around in the same direction - eliminating the potential for head-on or side collisions - to increase safety while reducing traffic congestion.

According to The Federal Highway Administration, traffic circles result in 35 percent fewer crashes, 76 percent fewer injuries in crashes and 90 percent fewer traffic deaths.

Existing Coralville roundabouts:

East Ninth Street and Quarry Road

First Avenue and Holiday Road

Twelfth Avenue and Forevergreen Road

Ridgeway Drive and University Court

University Parkway and University Court

Holiday Road and Corridor Way.

Heartland Drive west of Heartland Place

Commerce Drive and Commercial Park