Bridge Inspection and Ratings


MassDOT Bridge Load Ratings

MassDOT Bridge Load Rating Contracts, Statewide, MA: On-call contracts for rating of highway bridges to determine safe live load capacity of bridge structures in their current condition, considering deterioration and damage. Full analytical live load rating calculations were prepared for standard AASHTO H20, HS20, Type 3 and Type 3S2 trucks, using Allowable Stress Design and Load Factor Rating methods. Pursuant to the August, 2007 Minnesota Bridge collapse, all truss bridge ratings incorporated recommendations made by NTSB and FHWA for detailed structural analysis of gusset plates. Results were published in Rating Reports, developed per MHD criteria.

MBTA Bridge Inspection and Rating

MBTA Bridge Inspection and Rating Contracts, Statewide, MA:  On-call contracts for in-depth inspection / fracture critical inspections and load ratings for Authority-Owned (MBTA) highway, transit and commuter rail bridges in Massachusetts. Responsibilities included overall coordination and setup, plan and information gathering, field inspection, report preparation and quality assurance.


MassDOT Non NBIS Bridge Inspection

MassDOT Inspection of Non NBI Structures, Statewide, MA:  Gill is performing inspections of city and town owned bridges throughout Massachusetts. Structure types include concrete slab, steel stringer/girder, steel and masonry arches, masonry slabs, concrete culverts and steel pipes. Very few of the structures have plans, and none have ever been inspected. During the inspection, Gill takes measurements of all elements of the structures to provide accurate drawings to be included in the Initial Inspection Reports.



The effort starts with research of available information, including construction drawings, previous inspection and rating reports and repair records.  In-depth, hands-on inspections are then performed to document the condition of all structural elements and record any section losses or damage that may have been sustained by the structure.  Testing is performed to further evaluate material properties and structural condition, where necessary to supplement available records and inspection data.  A Bridge Inspection Report is prepared documenting the observations and findings from the inspection. 

The structural live load capacity of the bridge is then determined through computer modeling and a structural analysis that incorporates the existing physical geometry of the bridge.  Observations obtained during the bridge inspection are incorporated into the structural model to account for section losses, damage and other deficiencies.  Load ratings are determined for the appropriate rail or highway vehicles.  A Bridge Rating Report is prepared, documenting the findings, and informing the Authority of the rating.  Deficiencies are highlighted and recommendations for repairs are given.