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

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

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

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

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

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

Bridge Rating for SHVs Type M3 Type M3S ’ 80 kips Type M3S3 16’ 48 kips  Minnesota legal trucks used to determine load posting 47’ 80 kips

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

Rating Contract

 $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

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

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

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 SHV’s Ratings must meet AASHTO Manual for Bridge Evaluation, MnDOT LRFD Bridge Design Manual requirements Perform a complete QC of each rating

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

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

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

Br. No

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

Br. No. L3612  Abutment pile failure from earth pressure

Br. No. L3612  Deteriorated abutment pile

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

Br. No

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

Br. No

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

Br. No

Future Project  Phase II $500,000 budget, 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

Questions?