Diverging Diamond at K-18/K-113

Phase 1 Traffic Plan

Phase I Diverging Diamond Interchange

Traffic Impact

On April 5, weather permitting, construction on a new diverging diamond interchange project will begin at the existing 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.
  • 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.
  • Phase 3: Construct concrete barriers. Traffic impacts: Access to Allison Avenue will be closed.
  • Phase 4: Construct concrete medians. Access to Allison Avenue will be reopened once traffic signal installation work is completed in the south crossover area.
  • Phase 5: Construct final 1.5-inch asphalt overlay and installation of permanent pavement markings and signage.
Beginning April 5, northbound and southbound K-113 traffic will be reduced to one lane in each direction throughout the project duration. K-18 through traffic will not be impacted. K-113 traffic will have one 12-foot lane width restriction each direction and a posted 25 mph speed limit through the work zone throughout the project duration. Traffic will be directed through the project work zone via barricades, cones, and signage.
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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