Johnston NW 86th Street Side-Path

Challenge: The NW 86th Street Side-Path project is the third phase of improvements along the NW 86th Street corridor and will provide multi-modal connectivity and fulfill the 2018 City of Johnston Walkability Study goals.

The project involves construction of a 10-foot shared-use path along the east side of the roadway along with updated pedestrian safety improvements at intersections to bring pedestrian curb ramps, push-button pedestals, and crosswalk indication into compliance with current ADA and PROWAG regulations and guidelines.

Solution: During design, additional grading considerations were required at the three separate drainage channels the proposed trail was required to cross. In order to avoid significant costs associated with drainage culvert extensions, the HR Green team identified six separate retaining wall locations and applied various retaining wall systems (segmental and modular block as well as SUDAS 9072.221 Combined Retaining Wall-Sidewalk) to contain the necessary fill for the trail and parking slope construction.

During construction it was discovered that the initial plan for franchise utility support and protection during segmental block retaining wall reinforced zone excavation and geogrid/reinforced backfill placement would result in a significantly longer construction schedule and potentially pose safety concerns for workers. The HR Green team, in coordination with the City and contractor, evaluated the application of the ReCon Retaining Wall system that would function as a gravity block that did not require the geogrid and reinforced backfill zones of typical segmental block wall products.

The Green Meadows West Homeowner’s Association (HOA) encompasses over 60% of the corridor length; therefore, significant proactive engagement with the HOA Board was paramount to getting the necessary right-of-way acquired along with the necessary separate easements for City, Public Utility, and MidAmerican Underground Electric. These were all obtained via donation by reaching an agreement for the City’s construction project to remove the existing evergreen screening and replace with an earth-graded berm design.

HR Green and the City maintained a collaborative relationship with the Homeowner’s Association throughout construction by holding private walk-throughs with HOA Board members to update them on progress, discuss property owner concerns that had been brought to their attention, and coordinate with their lawn care and irrigation representatives to address situations that will improve the long-term maintenance of the property.

Ultimately the HOA privately funded the landscape design and installation of a planting layout through the established berm areas in order to re-establish the roadway screening for the adjacent properties as well as provide an aesthetic amenity to the corridor. The HR Green team’s ability to form and facilitate collaborative partnerships between our clients, contractors, and project stakeholders proved effective on delivering the NW 86th Street Side-Path project for the Johnston community.

Benefit: The Johnston NW 86th Street Side-Path project will fulfill the City’s vision of a Complete Streets facility for this corridor, as it was identified in the City’s Walkability Study as an important route for improvements.