Toboggan Road Bridge Replacement

Toboggan Road Bridge Replacement


The Toboggan Road bridge was structurally deficient and was located in a rural area with flat terrain. During rain events, the roadway was overtopped and during preliminary investigations, it was determined that it was not in the typical fashion of upstream to downstream.

Adjacent landowners had modified a downstream ditch in an effort to reduce water ponding in fields. The unintended consequence of the modifications is that a “levee” was created, with the water in the ditch back feeding over the road, creating unsafe conditions for motorists.


WHKS presented a solution to raise the road to provide freeboard above high water in the ditch, creating a combination entrance that also acts as an overflow weir. Even though the road was raised, the profile could not be increased sufficiently to accommodate a bridge. Doing so would have created a “perched” bridge and created a bump in the flat terrain.

The existing 11″ PPC structure was replaced by a non-standard 20′ by 6′ single-cell, cast-in-place concrete culvert. IL DOT Standard Culvert Designs extend to 12′ for single cells, so the 20′ required design and detailing beyond typical standards. The project required coordination with the adjacent landowners and many meetings with regulatory agencies for approvals.


  • Culvert design
  • Roadway design
  • Hydraulic design
  • Preparation of Illinois DOT Preliminary Bridge Design and Hydraulic Report, Project Development Report, Bridge Condition Report and SLRS Report
  • Permitting and Environmental Survey Request
  • Phase 3 assistance