The existing Cranbrook Road Bridge is integrated into adjacent Cranbrook Educational Community (Cranbrook) structures with no distinguishing demarcation of where the City's bridge transitions into the campus facilities.  Adjacent to the Cranbrook Road Bridge lies brick and stone walls and a portion of the Kingswood school both which contribute extensively to Cranbrook's national historical designations.  A second important feature of the bridge is a sculpted iron art work display that is utilized as a bridge railing within an opening on the bridge walls.  The sculpted iron railing did not meet current bridge railing safety standards.  However, relocating the iron railing off the bridge or setting it in front of or directly behind a concrete crash barrier was not appropriate in order to maintain its historical contribution to the Cranbrook Campus.

Concerned that conventional bridge construction techniques would impact these structures, less disruptive construction methods were specified to minimize impacts.  These included drilled caissons and braced excavations, pre-construction structure condition surveys and vibration monitoring.  Demolition of the existing bridge, including the removal of unknown buried footings and twenty-two drilled caissons, over 30 feet deep, were completed without incident.  Additionally, in order to minimize demolition impacts, the existing bridge abutments were used as cofferdams and the new bridge system was built over this existing substructure.

HRC worked with the City, Cranbrook, and a historic preservation sub-consultant to HRC, to determine that the site's historical significance could be maintained if the road was shifted away from the iron railing to allow for a parallel sidewalk and acceptable FHWA bridge railing to be placed between it and the roadway.  This created a safe bridge crossing for vehicles and pedestrians with only minimal obstruction to the artistic balance of the setting.  HRC surveyed and inventoried every aspect of the iron railing's surroundings including each individual cap piece of the existing wall and designed a structurally sound and crash worthy wall core that specified the reuse of the existing bricks and wall caps to create a façade that replicated the existing walls.  The result is a relocated road on an entirely new bridge that looks as though the walls and sculpted iron railing were left in place and all other improvements built around them.

HRC responsibilities included:

• Perform a detailed site investigation
• Topographical Survey
• ROW/Easement
• MDEQ Permit Application
• Hydraulic/Scour Analysis
• Utility Coordination
• Historical Preservation
• Bridge Design
  • Coordinate geotechnical soils investigations
  • Coordinate vibration monitoring/drilled pier inspections
  • Foundation/Pier Design
  • Substructure and superstructure design
• Prepare project plans, specifications and construction cost estimates
• Contract Administration
• Construction Engineering Support and Construction Observation
• Materials Testing