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Interchange Upgrades Drive Critical Roadway Improvements

tower terrace roadway mapNearly two decades ago, planners for Linn County and several surrounding communities — including Cedar Rapids, Hiawatha, and Marion — began laying the groundwork for an east/west crosstown route along the northern edge of the Cedar Rapids metro area. Stretching from Interstate 380 in the west to Highway 13 in the east, the Tower Terrace Road corridor was the preferred option to provide access to an area with a projected population growth of 40,000 by 2040. A significant piece of this northern connector was recently realized with the upgrades to the I-380 interchange and the extensive roadway improvements on both sides of the interchange.

The new interchange was reconfigured to a Diverging Diamond Interchange (DDI) formation to improve efficiency and safety. Working in conjunction with the interchange design group, the Iowa DOT, and multiple jurisdictions, the team from Snyder & Associates was chosen to design the critical roadway elements on either side of the interchange to ensure a smooth and safe transition for motorists.

West Side Roadway Improvements

On the west side of the interchange, our group was tasked with developing designs to reconstruct Tower Terrace Road from 1,000 feet west of Miller Road to the I-380 interchange. This included updating the roadway from a rural section to an urban section with pedestrian accommodations.

Staging for the project construction was critical for maintaining access to nearby homeowners and a busy commercial business on the south side of the roadway. Our team designed a temporary access road along the south side of the street between Miller Road and Twisters Gymnastics to maintain access during construction. On the north side of the roadway, a temporary entrance and gapped paving were used to maintain access to an impacted homeowner. In addition to coordinating with the numerous utility conflicts in the project area, we devised a plan for temporary drainage during the staged construction to alleviate stormwater concerns.

During design, our team was continuously in contact with the IDOT’s consulting engineer for the DDI portion of the project to ensure our design matched the interchange tie-ins. We also prompted numerous design team meetings with the IDOT to ensure seamless project coordination.

East Side Roadway Upgrades

Road traffic transitions into roundabout

North Center Point Road traffic transitions into the roundabout at Tower Terrace Road.

To the east of the interchange, constructing a roundabout at the North Center Point Road intersection was a critical infrastructure upgrade to improve efficiency for drivers near the new DDI interchange. This joint project between Hiawatha and the Iowa DOT was also constructed concurrently with the interchange.

The roadway upgrades include a 4-lane section with a sidewalk on the north and a 10-foot-wide trail on the south side just east of the interchange. The roundabout was designed with a single through lane for north and southbound traffic, dedicated eastbound and westbound right turn lanes, and two through lanes for eastbound and westbound traffic. The design and construction allow for the future addition of another northbound and southbound lane without requiring reconstruction or road closures. Our team’s design also alleviated environmental concerns relating to the Tower Terrace Mobile Home Park adjacent to the new section of the roadway.

As with the west side improvements, extensive coordination meetings with the DOT’s consulting engineer were initiated to ensure interchange project alignments and profiles matched. We also designed the west and east side improvement projects to be a “mandatory tie” with the I-380 interchange project. This allowed all three projects to be completed under the same contract and timeline, saving the client money through a larger scoped project, which attracted a large pool of contractors.

Tower Terrace Road stands to become an essential commercial corridor that will promote sustainable development and help the surrounding communities become more vibrant. With a considerable piece of this northern connector now open, this long-planned objective may be realized sooner than expected. The Snyder & Associates team has also been active with other sections of this vital corridor connection. It looks forward to providing services to all agencies and communities involved in bringing this extensive project to a successful conclusion.