Cutting Risks with Inspections

This article describes an engineering firm’s approach to repairing Heroes Tunnel, which was constructed in 1949 and is the only highway rock tunnel in Connecticut. The 0.4-kilometer long tunnel consists of two 8.5-meter wide and 5.8-meter high tubes, which intercept a significant amount of underground water. As the tunnel has aged, its safety has become compromised by the water, particularly during winter when icicles form and drop on the tunnel floor causing icy patches. The article describes in detail the method of inspection of the tunnel that was undertaken by the firm in order to mitigate risk. Some considerations included a lack of understanding of the original design and construction criteria, a lack of geotechnical details, and no as-built record of construction. In addition, the article notes that much has changed in the intervening 60 years in terms of the technology of ventilation, drainage, and lighting, all of which would add restrictions in increased cost to remedial measures.