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Rating of Local Bridges for SHVs Using Virtis Software Virtis/Opis User Group Meeting August 3-4, 2010 Moises C. Dimaculangan, P.E. Minnesota Department of Transportation

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Presentation Overview Specialized Hauling Vehicles (SHVs) Bridge Rating for SHVs Rating Contract Rating Analysis Challenges Future Project

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Specialized Hauling Vehicles What is a SHV? Single unit (SU) trucks with closely-spaced multiple axles Maximum load of up to nearly 80,000 lbs Must meet the Federal Bridge Formula B Considered legal and typically allowed unrestricted operation Examples: Gravel Trucks, Redi Mix Trucks, Milk Trucks

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Specialized Hauling Vehicles SU4 18 54 kips 62 kips SU5 22 69.5 kips SU6 26 77.5 kips SU7 30

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Bridge Rating for SHVs Why is bridge rating important? SHVs are increasingly common on our roadways Effects on short span bridges Fulfill National Bridge Inspection Standards (NBIS) requirements Update local bridge rating database

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Bridge Rating for SHVs Why is bridge rating important? (cont.) Create a consistent summary of load carrying capacities of all state bridges Used for bridge posting and for issuing overweight permits Monitor safety of bridges over time Determine when rehabilitation or replacement is needed

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Bridge Rating for SHVs Type M3 Type M3S2-40 51 80 kips Type M3S3 16 48 kips Minnesota legal trucks used to determine load posting 47 80 kips

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Rating Contract Funding - $800,000 from FHWA and State Aid 14,786 bridges in the local system Bridge selection process Operating Rating < HS 27 Rating date, 30+ years old Rating Method Bridge type Local agencies input - 2 year replacement 581 bridges selected for rating

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Rating Contract

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$1400 /bridge Data gathering, field investigation, inspections, rating analysis 4 bridge rating contracts $200,000/contract Bonestroo national firm HDR national firm LHB local firm WSN local firm

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Rating Contract Phase I May 2010 May 2011 Impact of the project is statewide Heaviest concentration of work located in southern Minnesota

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Rating Contract Scope of work Information and Data Gathering Examine current inventory rating sheets and inspection reports Examine bridge files and records Field Investigations Bridge inspections Field measurements

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Rating Analysis Virtis 6.1 Bridge will be rated in Virtis Provides consistency in rating Bridges not compatible with Virtis will be rated by hand or other design approved software such as MDX Rating analysis based on AASHTO Design Trucks, MnDOT Legal (posting) Vehicles, and SHVs Ratings must meet AASHTO Manual for Bridge Evaluation, MnDOT LRFD Bridge Design Manual requirements Perform a complete QC of each rating

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Rating Analysis Virtis 6.1 (cont.) Rating method Reinforced and prestressed concrete bridges will be rated for both LFR and LRFR methods Steel bridges - LFR method Timber bridges - ASR method

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Rating Analysis Virtis 6.1 (cont.) Why use Virtis for local bridges? Consistent with TH system Ease of permitting with local bridges Ease of re-rating bridges when a change in rating codes, bridges condition or truck configuration occurs

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Challenges No plans available Timber and steel bridges Prestress concrete bridges Physical Inspection Rating (PIR) No Access Bridge No. 88494 Built in 1950 Concrete Slab Span 12ft in length Operating Rating = HS18, Date: 1973

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Br. No. 88494

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Challenges Deteriorated Substructures Bridge No. L3612 Built in 1958 Timber Slab Span 26ft in length Operating Rating = HS26, Date: 1974

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Br. No. L3612 Abutment pile failure from earth pressure

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Br. No. L3612 Deteriorated abutment pile

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Challenges Unique Design Bridge No. 92079 Built in 1958 Steel Beam Span 16ft in length Operating Rating = HS20, Date: 1973

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Br. No. 92079

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Br. No. 90343 Concrete slab span 20ft long Built in 1923 Operating rating = HS19 Rating Date: 1973 No plans available

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Br. No. 90343

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Br. No. 94063 Steel beam span 17ft long Built in 1941 Operating rating = HS20 Rating Date: 1973

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Br. No. 94063

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Future Project Phase II $500,000 budget, 2011-2012 contract FHWA audit of load ratings and postings Emphasis on load rating updates Help locals with permitting by giving them procedures and guidelines Accommodate changing truck weights

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Questions?