City of Grand Island

Sycamore Street Underpass Rehabilitation Design

Grand Island, NE

Based on recommendations of two engineering studies and voter approval of a one-half percent sales tax increase, the City of Grand Island is rehabilitating the Sycamore Street underpass, a structure built in 1950 which serves as a main thoroughfare through the City. The cost of repairs and replacement are estimated at $2.5 million and would extend its service life another 30 years. Alfred Benesch & Company (Benesch) was selected for project design as well as bid document preparation for project letting in 2018.

The most significant issue to be addressed is extensive deterioration of the existing Front Street bridge. Public safety interests require its removal and replacement with a structure that conforms to current design standards. In addition, pumps removing stormwater runoff have well exceeded their design life and are requiring substantial maintenance investment to keep them functional. Subsoil washout caused street pavement on the east and west sides of the underpass to drop several inches. Sinkage is also linked to the inward tilting of underpass walls.

The Benesch team developed plans for reconstruction of the South Front Street bridge over Sycamore Street; replacement of the outdated stormwater drainage system; and repair of the retaining walls along Sycamore Street between 3rd and 4th Street.

Along with data collection, groundwater analysis, stormwater drain system investigation and analysis and utility coordination to rehabilitate the bridge, Benesch prepared plans for roadway improvements on Front Street at both ends of the bridge. Road surfaces behind the retaining walls south of the bridge were designed to achieve positive drainage. Pedestrian accommodations will be provided on the north side of the bridge.

This project is a top priority for the City of Grand Island. Sycamore Street is a crucial route that allows emergency vehicles to get from the south side to the north side of town without being blocked by one of the more than 70 trains per day on this corridor.

Benesch and the City anticipate two years for project construction.

Project highlights

  • Cost/Benefit Analysis of Multiple Alternatives
  • Bridge Replacement
  • Retaining Wall Repair
  • Storm Sewer and Drainage Improvements
  • Traffic study, simulation, turning movements
  • Value Planning / Function Analysis
  • Survey
  • Geotechnical Engineering