Diverging Diamond at K-18/K-113

Phase 5 Construction Plans - Starting October 24

DDI - Phase 5

Traffic Impact

Construction on a new diverging diamond interchange project is underway at the K-113 and K-18 interchange. Project work includes replacing the existing diamond interchange with a new diverging diamond style interchange on K-113 at K-18 (K-18 bridges will not be impacted). Work will take place during daylight hours, Monday through Friday, with some occasional weekend work.

Project construction will be completed in five phases with traffic carried through the project in both directions as follows:
  • Phase I: Construction of west half of project, including the ramps from K-113 to westbound K-18 and eastbound K-18 to K-113. Traffic impacts: Access to Allison Avenue will be closed. (April 5-June 26)
  • Phase 2: Construction of east half of project, including the ramps from westbound K-18 to K-113 and eastbound K-18 to K-113. Traffic impacts: Access to Allison Avenue will be closed. (June 27-Aug 30)
  • Phase 3 & 4: Construct concrete barriers and concrete medians. Traffic impacts: Access to Allison Avenue will be closed.(Aug 31-Oct 23)
  • Phase 5: Construct final 1.5-inch asphalt overlay and installation of permanent pavement markings and signage. Traffic Impacts: Access to Allison Avenue will remain closed until final overly is complete (Starts Oct 24)
Beginning October 24, expect significant delays and lane shifts while asphalt is being placed at the intersection and the on and off ramps for the Seth Child Rd. and Fort Riley Blvd Interchange. Please follow all posted traffic signs and be aware of construction activity while in this area.  The use of alternate routes is recommended.  This phase of construction is expected to be completed by Tuesday October 31. K-18 through traffic will not be impacted. Access to Allison Avenue from Seth Child remains closed until the final overlay is complete, but Allison remains open to through traffic. Please use caution, obey all posted traffic control and slow down in the work zone.
Diverging Diamond Interchange

Project Description

A diverging diamond interchange is planned at the intersection of K-18 and K-113 (Seth Child Road). The City of Manhattan submitted a geometric improvement grant application in 2012 to reduce delays for traffic turning onto eastbound K-18 from either direction of Seth Child Road. A study by Benesch & Co. found the diverging diamond was the most favorable to achieve the goals of the project. Pedestrian and drainage improvements will be made along with the transportation improvements. Amino Brothers Co. of Kansas City is the contractor. 

Want to know how a DDI works? Watch this video of KDOT's first completed DDI in Johnson County.


According to the grant application, the city is responsible for the first $1 million of the project, the state for the next $2 million, and the city for any remaining project expenses that exceed $3 million.


Bid letting (KDOT)  December 2016
Concurrence with bid (City) January 2017
Construction to begin April 5, 2017
Anticipated substantial completion date November 2017
Project completion April 2018

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