SMART Bridge Campaign – Open Restricted Bridges

Problem: Every bridge in developed countries is mandated to be inspected every two years (bridge inspection expense over $3 billion annually estm.) There is a budget in every municipal government’s annual spend for the inspection, maintenance, rehabilitation and new construction of bridges. The rating of these bridges uses an old system of visual inspection based on external assessment and classification of the state of the bridge. This approach, while the best that existed 50 or 100 years ago, does not incorporate the technology available today. The result of this classification is a conservative assessment based on design information and judgement. This lack of information on the specific state of each bridge is especially critical at the end of the design life. The result of inadequate information is that 9 out of 10 bridges torn down and re-built have many years of service life left.

“I have inspected 100’s of bridges in Canada and 9 out of 10 times the bridge can be saved”.
Most structures rated as structurally deficient can be safely operated with testing and continuous real- time monitoring.
Baidar Bakht PhD – Member of the Order of Canada – former Principal Research Officer Minister of Transportation Ontario CA

Solution: Innovation in Information Decision Support for Bridge Management The solution to this problem is not just to spend more but to also spend wisely. Innovative new technology exists that will support the rehabilitation and extend the life of existing bridges and can be incorporated into new bridge construction and management. Bridges can be higher performing structures with the goal to build 100 year bridges and not the present 50 year life. Manitoba is able to extend 50 year design life to 80 + year service life. The past 15 years using Structural Health Monitoring. Ruth Eden Director Design and Construction and of Preservation and Planning – Manitoba Canada Infrastructure and Transportation.

SMART Bridge Campaign: Intelligent Structures will work with you to implement a program where posted or critically structurally deficient bridges are live load tested and continuously monitored to reduce or eliminate the traffic restrictions on the bridge. Through our IntelliStruct solution we can provide a technically reliable solution at a economical cost providing substantial return on investment.

CASE: LOAD TESTING FOR BRIDGE RATING: DEAN’S MILL OVER HANNACROIS CREEK
REPORT FHWA/NY/SR-06/147

New York State Posted Bridge with load limit of 12 tons – No School Buses

VI. CONCLUSIONS AND RECOMMENDATIONS

The major test and analysis results findings presented in this report can be summarized in the following:

1. Load distribution on the structure was excellent in comparison with that of the estimated AASHTO equation.
2. The theoretical beam section modulus was verified using results based on strain readings from gages mounted to determine neutral axis locations and again from moment versus strain results.
3. The testing revealed that the structure was about 90 percent fixed at the South end and about 76 percent fixed at the north end.
4. AASHTO LFD load rating was performed using a conservative approach, assuming the structure to be simply supported, the actual AASHTO distribution factor, and the theoretical
   section modulus, which was very close to that based on the test results.
5. The recommended H inventory and operating ratings are 24.6 and 40.8 tons, respectively.
6. The recommended HS inventory and operating ratings are 40.3 and 67.7 tons, respectively.

Based on these test results, a 15-ton school bus does not pose any hazard of damaging the structure.