Proposed roundabout to be first in state with signals

Feature would be firstof its kind in Missouri

  • 2 min to read

CARL JUNCTION, Mo. — Jasper County will be the guinea pig for another first-in-the-state construction project when the Missouri Department of Transportation builds a roundabout in 2021 for the intersection of Highways 171 and 96, and Route YY north of Carl Junction.

According to Craig Switzer, MoDOT transportation project manager, the multilane roundabout will include signal lights for some of the traffic going through it.

Motor vehicle traffic that uses a Kansas City Southern Railway grade crossing on Highway 96 immediately west of the roundabout design will be controlled by stop lights that activate only when a train is approaching or crossing. The KCS tracks run parallel to Highway 171 in that area.


The design offers the following options for drivers:

• Traffic going west on Highway 96 will have three lanes from which to choose: one going right to go north on Highway 171, one in the middle to go west across the tracks to Route YY and one on the left to go around the roundabout and south on Highway 171. The middle lane will have a traffic signal that will stop traffic when a train is coming. All other lanes will be able to proceed unimpeded.

• Traffic going north on 171 can choose the left lane to go west on YY or the right lane to go east on Highway 96 or straight north. The left lane will have a signal on it to stop traffic when a train is crossing. The right lane will not have a signal.

• Traffic going south on Highway 171 will have a right-turn lane to go west across the tracks and a lane to go around the roundabout and either turn left to go east on Highway 96 or south on 171.

• Traffic going east on YY will have a traffic signal that will stop all vehicles before they cross the tracks.

Switzer said the roundabout will have overhead signs and markings on the road to show drivers which lanes to choose and where to stop.

He said the train tracks so close to the intersection made all options complicated and forced the department to move the entire intersection several feet to the east.

“Our traffic people and consultants looked at it and ran several simulations with a few different configurations,” Switzer said. “I know we looked at just having a left-turn lane there and some other options. This one was the one that handled traffic the best.”

Current problems

Switzer said with the current configuration, tractor trailers going east on YY can cross the tracks, but if they have to stop at the stop sign on Highway 171 for traffic, their trailers could still be in the railroad crossing.

The elevation of the tracks and the road at that intersection also has resulted in some types of tractor-trailers high-centering on the tracks and getting stuck.

A truck carrying boats was hit at that crossing in 2010 when it high-centered on the tracks. No one was hurt in that crash because the truck driver was able to escape the tractor before the train hit it.

“We’ve had some trucks get hung up on the tracks, and as it is, there’s not enough room for an eastbound truck to park at the stop sign and wait for traffic,” Switzer said. “The safety aspect there was the main thing when we started looking at this location. You’ve got Highway 171 being pretty high-speed, you’ve got Highway 96 being pretty high-speed coming west and we’ve had some severe accidents there. So the safety aspect was number one, getting trucks off the tracks and a little more separation, and number two, slowing traffic down coming into a busy intersection.”

The traffic signals in some lanes will make this roundabout unique in Missouri, Switzer said.

“This is the first signalized roundabout in the state,” Switzer said. “There will be signals to stop the traffic when the train comes through but just on the lanes that are going across the tracks. Everybody else is free to go.

City concerns

Carl Junction City Administrator Steve Lawver attended the meeting and studied the design closely.

Lawver said he was concerned because traffic will have to be detoured through Carl Junction on County Route Z during part of the construction process.

Switzer said details are still being worked out as to how long that detour will have to last, but most of the construction of the roundabout will not require the detour.

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