Bridging Two Cultures - Madawaska International Bridge-PPT Presentation

PPT Presentation

Pdf Summary

The Madawaska International Bridge project replaces the 1920 four-span bridge connecting Madawaska, Maine, and Edmundston, New Brunswick. The existing structure was nearing the end of its useful life, with deteriorated members, inadequate load capacity, geometric constraints, and extensive repairs. The replacement is an approximately 1,850-foot, six-span bridge crossing railways, steep riverbanks, and the Saint John River. It connects a new U.S. port of entry upstream to the existing Canadian port of entry.<br /><br />Foundation design was complicated by restricted site access, steep banks, and highly variable bedrock depth and conditions. Because shallow, fast-moving water and steep riverbanks prevented conventional river access, the team used an over-water seismic refraction survey to estimate rock levels. Later borings refined the subsurface model; difficult-to-reach river locations were accessed by helicopter using a custom platform.<br /><br />The design accommodated different ground conditions at the abutments and piers. Multiple foundation alternatives were developed for bidding, including driven piles and drilled shafts at Pier 1, and spread footings or drilled shafts at Piers 2–5. Drilled shafts were designed to rely on side resistance in rock, with permanent casing, rock sockets, and instrumentation.<br /><br />Construction observation included confirmation borings, monitoring casing and socket excavation, and quality checks before concrete placement. Shaft integrity was assessed using Thermal Integrity Profiling (TIP) and Cross-hole Sonic Logging (CSL). The presentation compares the methods: CSL provides repeatable results but cannot assess concrete outside the reinforcing cage, while TIP can reveal shaft shape and integrity beyond the cage but depends heavily on accurate input data and must generally be conducted soon after installation.

Keywords

Madawaska International Bridge

bridge replacement

Saint John River

foundation design

drilled shafts

seismic refraction survey

helicopter borings

thermal integrity profiling

cross-hole sonic logging

New Brunswick