Client:
Michigan Department of Transportation

Location:
Detroit, Michigan

Prime Consultant:
Wade Trim Associates

Sub Consultant:
NTH Consultants, Ltd.

Total Project Contract Values:
$300,000

Total NTH Budget:
$98,000

Project Start:
March 2001

Project Completion:
December 2001
NTH’s Value Added:
​NTH provided structural engineering and materials engineering expertise to develop a needs assessment for bridge repair.  Our evaluation contributed to development of cost-effective, and efficiently prioritized repair recommendations.
1-75 Bridge 
Structural Investigation
Project Overview
The Michigan Department of Transportation retained a team of experts, including professionals from NTH Consultants to perform bridge scoping services on the
I-75 Rouge River bridge deck. 

Project Scope
NTH’s contribution to this extensive undertaking, included:
  • Taking 152 cores from the deck, including five from each ramp, and using the following tests to evaluate the concrete:
    • Air Void Analysis
    • Petrographic Analysis
    • Chloride Ion Penetrability
    • Compressive Strength
  • Hand sounding approximately five percent of the entire deck to locate delaminations and other problem areas 
  • Surveying the deck from the surface with Ground Penetrating Radar (GPR), to find anomalies

NTH participated in developing and supporting repair recommendations, including:
  • Considering material test results to evaluate the overall quality of the deck substrate
  • Conducting further analysis on a span-by-span basis to rate spans from best to worst (reflecting the problem areas identified)
  • Using a condition matrix to develop criteria that provided a “yard stick” for analyzing data and rationale behind the prioritization of recommendations
The team developed prioritized, span-by-span, recommendations for deck rehabilitation on a total of 217 spans of concrete deck.  Recommendations ranged from immediate action to postponement until the total deck replacement planned for 2017.