The design of the roundabout on Prairie Dell Road must be changed to accommodate large tractor-trailers, according to city officials.

City Engineer Jonathan Zimmermann presented a preliminary design of the roundabout on Prairie Dell Road at Denmark Road and the entrance to East Central College.

He said the design was drawn to accommodate trucks that are 73 1/2-foot in length.

“This design has to be modified because (truck tires) are getting up on curbs,” he said.

There had been changes made to the Washington Avenue and Independence Drive roundabout after its completion because some trucks could not make immediate right turns due to an inaccurate design.

Zimmermann said that the design did not take into account the location of the rear axles on some large trucks.

The design firm of Horner and Shifrin, St. Louis, which is designing the Prairie Dell roundabout, will make modifications to accommodate those trucks.

Mayor Mike Livengood noted that there is a “slip lane” that allows vehicles southbound on Prairie Dell Road to make an immediate right and enter into the college without accessing the roundabout.

That will alleviate any stacking in the southbound lane of the intersection.

“Most people will use that,” he said. “About half of the cars will be going into the college and boom they’re in there.”

Zimmermann added that there is some stacking at that intersection now, which will be “released faster and much safer” once the roundabout is open.

Prairie Dell Project

The project, which is Phase I of two on the roadway, is slated to begin in the spring of 2015.

According to preliminary plans, the entrance to the school will be shifted north slightly where a roundabout intersection will be built.

Zimmermann said the intersection would be constructed while school is not in session, and it would take about 60 days to complete the roundabout. During that time traffic would be detoured.

Prairie Dell Road improvements are in the Transportation Improvement Program (TIP) for 2012-2015.

The project includes pavement improvements, pedestrian enhancements, curb and gutter work and widening of the road.

The cost to upgrade the road is estimated at $1,370,000. The project is an 80-20 cost share project and the city will provide 20 percent of the project cost.

The funds were available through the East-West Gateway Council of Governments’ Surface Transportation Program — Suballocated (STP-S) pool available to area communities.

STP-S funds can be used for projects such as pavement preservation, bridges, highway expansion, congestion mitigation, safety, environmental mitigation, transit and pedestrian facilities.

The second phase of the project would extend the improvements on Prairie Dell Road to College Road.

The scope of the Phase II project includes widening of the roadway, and new sidewalks. The project is estimated to cost $1,352,250.