MBTA Bridge Inspections and Load Ratings
AI is performing in-depth inspection and load rating for Authority-owned bridges for the MBTA that carry commuter, freight, and light rail transit tracks. This contract consists of 57 bridges in Boston and nearby towns, and the structure types include steel multi-girders, box girders, through girder and floorbeam systems, built-up deck girders, reinforced concrete and masonry arches, cast-in-place concrete frames, prestressed concrete girders, etc. The bridge inspection reports are being prepared in the MassDOT 4D database for the first time and will be submitted electronically and as a hard copy.
All work is performed in accordance with NBIS, FTA, AREMA, MBTA, and MassDOT guidelines. The scope of work includes review of plans, previous inspection and load rating reports; scheduling of lane closures, police details, and railroad flaggers; installation of temporary traffic control, field inspection and evaluation, and non-destructive testing; and preparation of inspection reports. Inspection types include in-depth, fracture critical, and underwater. The bridges are accessed with bucket trucks, hi-rail snoopers, boats and barges with scaffolding and boom lifts, and bridge trackers. Scheduling is coordinated with Keolis Commuter Services and MBTA Operations for railroad flagging, as well as with MassDOT District 6 for lane closures. AI has performed the majority of the temporary traffic control with our own personnel on this contract. Our inspectors are trained for Keolis Roadway Worker Protection, MBTA Right-of-Way Safety, and ATSSA Traffic Control. Many of the bridges are fracture critical. These inspections require advance planning, including preparation of bridge plan and elevation views identifying fracture critical members and fatigue sensitive details as well as a specific fracture critical inspection procedure.
The deliverable is a comprehensive inspection report with a location map and bridge description, deficiency narrative, sketches, photographs, and edited SI&A sheet. In addition, a summary of inspection findings is provided with each report and categorized as critical, severe, or minor. Repair recommendations are included for each structural element based on the findings and are categorized as structural repair, monitoring, maintenance, and miscellaneous.
All the bridges to be rated receive an in-depth inspection first to verify their current condition. One of the bridges to be inspected and rated is the 33-span East Cambridge Viaduct across the Charles River and includes a movable double leaf bascule span, concrete deck arches, and a steel viaduct section with steel bents. A variety of software is being used to analyze and load rate the different types of bridges assigned in the project. The commuter rail bridges are being rated for Cooper E-80, F40PH (280K) Modified, HSP-46 Locomotive, 286K Rail Car, and 315K Rail Car in accordance with the current AREMA Manuals. Transit bridges are being rated for the relevant Revenue Car Load and Work Car Combinations as stated in the latest MBTA Guidelines for Load Rating of Transit Bridges.
AI is performing safety inspections of highway structures and bridges as well as support structures for traffic devices in the Fredericksburg District, VA. The scope of this contract includes routine and fracture critical bridge safety inspections, traffic control device inspection, bridge load capacity analysis, and special inspections for review of possible damage from overload vehicles, or damage from flood, fire, or vehicular accidents. To date, AI has been assigned 269 bridges and 812 ancillary structures for inspection and additionally, AI has performed 33 load ratings as part of this contract. The ancillary inspections have consisted of 393 light poles, 22 sign structures and 397 traffic signals. The ancillary inspections and reports have been performed in accordance with VDOT’s “Traffic Ancillary Structures Inventory and Inspection Manual”, and utilizing VDOT’s “Signs Inspection Program” database. Many of these structures have been located on I-95 and other high ADT Primaries presenting MOT challenges. AI is very familiar with the lane closure submittal process and coordinating with Northern Regional Operations, Richmond Traffic Operations Center, and with VDOT District personnel to ensure proper notification prior to any anticipated work. The bridge inspections on this project consist of a wide range of structures including major structures, with trusses, pin and hanger assemblies and fracture critical members. The work also includes in-depth bridge deck evaluations, ultrasonic testing, and underwater inspection. A wide variety of equipment is being utilized to perform this inspection work. AI has utilized multiple 75 ft. UBIT snoopers, a 60 ft. Elliott Hi-Reach man-lift, a 65 ft. bucket boat, bridge trackers, pontoon boats, safety boats, rigging, and bucket trucks to complete this assignment. In addition, the necessary truck mounted attenuators, cones and signage have been provided for MOT. The inspection report includes element condition state data, component ratings, bridge inspection and inventory information, vertical clearance sheets, structural deficiency detail sketches, and photos. Both bridge and ancillary Inspection reports are submitted in electronic format along with the necessary maintenance forms, redlined Pontis, and SI&A sheets, and the database files. Monthly progress reports of inspections completed are submitted to VDOT, and critical findings are issued at the time of inspection. We have on-staff supervisory level OSHA and ATSSA certified personnel who periodically monitor safety compliance during field operations. The project team consists of experienced bridge/structural engineers and senior staff to perform QC/QA of the field operations and reports. The following three major structures are part of this assignment:
- Norris Bridge (Route 3 over the Rappahannock River) – This bridge is nearly two miles long and consists of 44 spans. It contains steel girder spans, two girder floorbeam spans, and deck and thru truss spans. In addition, it contains 286 pins and hanger connections which will need to be inspected and require ultrasonic testing.
- Eltham Bridge (Route 30 over the Pamunkey River) – This bridge is over one-mile-long, 70 ft. wide, and consists of 48 pre-stressed concrete bulb tee spans, post tensioned for live load, and one two girder floor beam bascule span.
- Downing Bridge (Route 360 over the Rappahannock River) – This bridge is also more than a mile long and consists of 101 pre-stressed concrete beam spans.
2014 - Present
- AREMA/NBIS Guidelines
- Non-Destructive Testing
- Railroad Flagging
- Temporary Traffic Control
- Fracture Critical
- Structure Condition Survey
- Load rating