Improved Traffic Flow Results from Grade Separation
Situated in west-central Iowa, the City of Jefferson is the embodiment of a healthy and bustling rural community. However, one problem area that had troubled the community for years was the intersection of a busy, north-south arterial roadway (Iowa Highway 4) and the Union Pacific Railroad train tracks near the center of town. The tracks carry nearly 70 trains per day traveling at speeds up to 70 mph. Snyder & Associates was tasked with performing a feasibility study to assess the practicality of constructing a grade separation at the intersection to alleviate delays and safety concerns for pedestrians and vehicles.
Quality of Life Improvement: Grade Separation Lays Groundwork for Quite Zone
Subsequent to the feasibility study, the City of Jefferson pursued the establishment of a Quiet Zone through town. A quiet zone is an exemption to the Federal Railroad Association rule that requires trains to sound their horns when approaching public highway-rail grade crossings. One major obstacle in establishing a Quiet Zone was the existing crossing between Iowa Highway 4 and the railroad tracks. Separating those two facilities at that location was viewed as a necessary catalyst for commencing a Quiet Zone study and the quality of life improvement the city was looking to achieve.
Feasibility Studies Consider All Challenges to Provide a Clear Solution for Railroad Track & Highway Intersection
The goal of the feasibility study was to evaluate the viability of the project to ensure it’s technically, legally, and economically justifiable. The study also affords the opportunity to provide stakeholders a clear picture of the proposed project. A steering committee was formed comprised of representatives from local businesses in the City of Jefferson, Greene County, the Iowa DOT District 1 staff, Union Pacific Railroad, Snyder & Associates, and Shuck-Britson (a subsidiary of Snyder & Associates).
The study team faced multiple challenges in determining the optimal solution for the studied crossing. Specific areas addressed included:
- The need for a new access road system to serve businesses that would be affected by any construction or traffic-flow changes.
- Recognition of the need to accommodate for potential future growth in the railway service corridor.
- Consideration that any construction performed in the area would be done adjacent to a property listed on the National Register of Historic Places.
Grade-Separation Overpass Constructed to Minimize Traffic Delays & Increase Pedestrian Safety
Several alternatives were evaluated by the study to address the varied stakeholder concerns. A final recommendation on the preferred grade separation alternative was concluded after numerous meetings with the steering committee and the Iowa DOT staff members. This alternative included constructing a four-lane, eight-span, 1,100-foot long roadway overpass to carry vehicle and pedestrian traffic over the railroad tracks.
To minimize access impacts to local businesses, the bridge was also designed to span McKinley Street located just south of the tracks. Additionally, a new access road system was created to accommodate the affected business area. The access roads were constructed before work commenced on the bridge to facilitate for a smoother transition.
To meet the future growth needs of the Union Pacific freight traffic, the bridge was designed to accommodate a third railroad track. Also, to avoid any disturbance to the adjacent property listed on the National Register, the bridge foundations were designed to minimize damaging vibrations during construction.
Realization of Impact in Action
Snyder & Associates was the primary design consultant on the project, while Shuck-Britson provided structural bridge design. The services provided by our firm and sub consultant team covered every aspect of the $13 million project, from preliminary roadway design and management of public participation, all the way up to right-of-way acquisitions.