Leavenworth Increases Safety on 4th Street with Traffic Study

When the City of Leavenworth began planning pavement improvements to 4th Street between Seneca Street and Metropolitan Avenue (US-73/K-92), they wanted the design to meet both current and future transportation needs. As a key corridor connecting downtown, a military base, a highway, and an upcoming bridge replacement, 4th Street required careful evaluation.

As the City of Leavenworth readied for the project, they knew they needed to weigh their options. The area just south of this section had been recently redone, transformed from four lanes to three with a two-way turn lane (TWLTL). They needed to determine if this approach worked before making any improvements.

Our Traffic Team was selected to conduct a study. To find the right solution, they looked at whether this section could be reduced from four to three lanes of traffic. They performed traffic counts for all project intersections and analyzed crash history. They also projected traffic volume 20 years into the future to make certain their plan would grow with the City.

As they studied the project site, they considered adding turning lanes to reduce the likelihood of left-turn crashes. They also weighed the pros and cons of adding a traffic signal. Their research revealed three lanes would suffice due to low traffic volumes.

While our team was concerned with maintaining traffic flow, their primary focus was increasing safety. Moving to three lanes offers the City a number of benefits.

“A three-lane roadway design offers significant safety benefits without sacrificing efficiency,” said Addison Miller, PE, PTOE, Traffic Engineer. “To begin, it reduces speeding. It also decreases rear ends, as vehicles are no longer stopping in thru lanes to make left turns. And finally, while there weren’t many crashes in the area, there were some side swipes. These would also happen less frequently, as vehicles would no longer be traveling side by side.”

As they made their analysis, our Traffic Team also looked at the surrounding area. 4th Street connects to a highway, as well as the site of an upcoming bridge replacement. At the very north end of the project, there is a military base, and to the south, is Leavenworth’s downtown area. Coordinating our findings with both ends was challenging.

To be successful, they had to make certain the sections would reconnect smoothly, and that our recommendation would work with the other projects. For ease of navigation, they decided to stop the three-lane section at Pawnee Street and carry the 4-lane design from Pawnee Street to Metropolitan Avenue. This approach would accommodate the bursts of traffic from the military base when a checkpoint is in place and prevent cars from backing up on 4th Street. It would also maximize capacity at the Metropolitan intersection where the highway intersects with the entrance to the military base.

In addition to these improvements, they recommended signal modifications at Johnson Street. The only signal along the study corridor is located in front of an elementary school. The recommendations included realigning the signal heads for the new three lane section and moving the pedestrian pushbuttons to ADA compliant locations.

While the traffic study has been approved by the City, it is under review by the Kansas Department of Transportation (KDOT). 4th Street is a KDOT route, and as a result, the project is receiving agency funding. Prior to conducting our study, we met with KDOT to learn more about what they hoped to see in the improvements and any lessons learned from the project completed to the south on 4th Street that converted four lanes to three. Collaborating early has made this process more efficient.

When the study is approved, our team will move forward with the design of the project. Stay tuned for updates on how our recommendations are translated into a new roadway for Leavenworth.