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NW 70th Avenue Improvements

The City of Johnston is planning major improvements to NW 70th Avenue from the west city limits to NW 86th Street. Current conceptual plans include widening the road to four lanes with a median, roundabouts as intersection control at three locations, and the addition of a bike trail from NW 86th Street to connect to the Grimes trail. 

Check out this drone video taken over the construction site on August 16, 2016.

Update on the project
The section of NW 70th from NW 107th to the west and NW 107th from the north to NW 70th will be open to traffic starting September 19th after 9:00 AM. The opening of NW70th to head-to-head traffic through the entire project is projected to follow approximately 4 - 6 weeks later. Once again this schedule is weather dependent. The city and contractors are working diligently to achieve this projected schedule.


Current Detour Information:

NW 100th  NW 70th Access Routes 06242016.jpg


Presentation given at the public meeting on March 3, 2016

Click here to see overall map and plans for NW 70th Avenue.

Phase I - NW 98th Street to NW 107th Street

Estimated Cost:  $7,361,434.50

Estimated Road Construction Start Date:  Spring 2016

Estimated Completion Date: Late 2016

Contractor for Upcoming Roadway Improvements:  Alliance Construction of Grimes, Iowa

Engineer:  Foth Infrastructure & Environment, LLC

City Staff Project Contact:  W. David Cubit, Public Works Director, 515.278.0822

Project Status: 


Significant rain events slowed progress of NW 70th Avenue in late July and August. The main paving for the roundabout itself at NW 107th Street was complete on August 15. The bulk of the paving on NW 70th Avenue between NW 100th Street and NW 107th Street was completed on August 16 and 17. The contractor is working to complete the colored cross walks across street and the truck apron on the inside of the roundabout at NW 100th Street. The Contractor is also working on placing subdrains (similar to a sump pump drain in your house) adjacent to the back curb of the roadway. This requires use of the street to place material and is difficult and more costly to complete under traffic. As soon as this work is complete, the NW 107th Street intersection will be open to traffic. Barring any major weather delays, the goal is to have this complete by the middle of September. We appreciate your patience as we work to reopen NW 70th Avenue.

Phase II - NW 86th Street to Peckham Street, bid in the winter of 2017 and constructed in 2017 and 2018. The road will be closed to through traffic during construction.


Estimated Cost: Currently being determined.

Estimated Start Date:  Fall 2017

Estimated Completion Date:  Fall 2018

Contractor:  Yet to be determined

Engineer:  Foth Infrastructure & Environment, LLC

City Staff Project Contact:  W. David Cubit, Public Works Director, 515.278.0822

Project Status: Preliminary design phase

Phase III - Asphalt overlay of roadway between Peckham Street and NW 98th Street after completion of Phase II. There will be intermittent closures during construction.

Estimated Cost:  $830,000.00

Estimated Start Date:  After completion of Phase II

Estimated Completion Date:  Undetermined

Contractor:  Yet to be determined

Engineer:  Foth Infrastructure & Environment, LLC

City Staff Project Contact:  W. David Cubit, Public Works Director, 515.278.0822

Project Status: Preliminary design phase.

NW 70th Avenue.JPG

There will be no property owner assessments as part of Johnston’s project.  A thorough traffic study of the corridor was performed and concluded that a series of three roundabouts handles existing traffic and future increases in traffic.

Click here to learn more about roundabouts and why they're being chosen as the safest method for intersection control on some Johnston streets.

Current traffic on NW 70th Ave is 13,000 vehicles per day.  By 2035, traffic is projected to grow to 20,000-26,000 vehicles per day.  The proposed design accounts for this increase and concludes that acceptable levels of service will be maintained through 2035.

The impetus for the entire project is to be ready for the high school that will be built nearby and to address current and future traffic as the area continues to develop. This project will no doubt be a significant project for the City of Johnston. We couldn't do it without your input and patience.

We want to keep you informed every step of the way, so we are building an e-mail database.  Your e-mail will not be shared with anyone. If you would like to get on the list, please e-mail us here.

We encourage you to also "like" the City of Johnston Government Facebook page and also follow us on Twitter @cityofjohnston. We will provide frequent updates there and here on our website.  Click here for the latest updates. 

If you ever have any questions about the improvements, please feel free to contact
Public Works Director Dave Cubit.