Rural to Urban Roadway Reconstruction
Over the past two decades, rapid population growth in Ankeny has prompted the need for increased traffic capacity and improved safety, particularly along Northeast 36th Street between North Ankeny Boulevard and Northeast Delaware Avenue. In 2012, construction was finalized on the Interstate 35/Northeast 36th Street interchange project. While this project drastically changed the traffic patterns on the north side of Ankeny, it was also the catalyst for transforming Northeast 36th Street from a rural, two-lane roadway to a four-lane urban boulevard with left-turn lanes and expansive pedestrian walkways and sidewalks.
As the design engineer for this ambitious project, Snyder & Associates (along with our subsidiary Shuck-Britson) provided transportation, civil, traffic, and structural bridge engineering services. Additionally, our team designed a stormwater wetland and water quality basin located upstream from Fourmile Creek.
Phased Construction Process keeps Traffic Flowing
The Northeast 36th Street project has a strong regional impact due to its location and the surrounding transportation system. It’s highlighted in the Ankeny Comprehensive Plan as a municipal arterial, with plans to ultimately extend the roadway all the way west to U.S. Highway 415 as traffic volumes dictate. Our team was tasked with developing a plan for the Delaware Avenue to Ankeny Boulevard section in the most cost-effective manner possible. To achieve this goal, major components of the project were established for bidding and staging, including:
- Widening the existing bridge over Fourmile Creek
- Complete reconstruction of three intersections along the corridor
- Disconnecting one intersection from Northeast 36th Street and replacing it with a hammerhead configuration
- Addition of a traffic signal at the intersection of Northeast 36th Street and Northeast Trilein Drive
Due to the extensive scope of the project, construction was split into two phases to be built over two construction seasons. During phase one, the bridge over Fourmile Creek was widened to accommodate four lanes of traffic. This portion of the project occurred with the street fully open to traffic, creating limited inconvenience to drivers.
During phase two, our team recommended putting a detour in place and closing the road to all motorists except for local traffic. This strategy benefited the city in two specific ways. First, it greatly improved bid prices from contractors since they would not have to contend with traffic staging obstacles. Second, it allowed construction to occur during one construction season without a need for temporary pavement.
To avoid as many conflicts as possible during construction, our team closely coordinated with six franchise utility companies early in the design phase. The carefully crafted design minimized impacts outside the existing right-of-way, making temporary easement needs minimal throughout the 4,450-foot-long project corridor. Other project features include landscaping, a new storm sewer and water main, street lighting, and sidewalks.
Stormwater Treatment Installation Upstream from Fourmile Creek
A major highlight of the finished corridor project is a stormwater wetland and water quality basin built on city property south of the Woodland Reserve Greenway & Outdoor Education Center. Designed by the Snyder & Associates team, the wetland was installed upstream from Fourmile Creek to treat storm sewer outlet water before it enters the creek. The wetland also includes a grass trail open to the public with educational signage to explain the stormwater treatment process.
To recognize the significance of the new stormwater wetland, a ribbon-cutting ceremony was held in 2018. Attended by Iowa Governor Kim Reynolds and Iowa Secretary of Agriculture Mike Naig, the Governor also signed a proclamation declaring April 29 through May 6 as Iowa Soil and Water Conservation week.
With the improvements in place, the newly upgraded Northeast 36th Street corridor is now equipped to provide adequate safety and capacity for the ever-increasing regional traffic.