On July 10, 2006, a section of suspending ceiling panels in Boston’s I-90 Eastbound Connector Tunnel collapsed onto live traffic tragically killing a local woman. The Connector Tunnel is part of Boston’s “Big Dig” tunnel network, formerly known as the Central Artery/Third Harbor Tunnel (CA/T) project, which was being operated and maintained by the Massachusetts Turnpike Authority. Following the collapse, then Governor Romney took control of the investigation ordering the Executive Office of Transportation (EOT) to perform and oversee an independent evaluation of the tunnel’s condition.
On July 25, 2006, DTC was hired by the EOT under the direction of the Massachusetts Highway Department (MHD) to perform emergency safety inspections of the CA/T tunnel system. Work began immediately, when DTC mobilized staff the next evening to inspect anchorage systems for two large air-circulatory jet fans located in Ramp F, one of the connector tunnels.
Since that initial assignment, work continued at a brisk pace where DTC conducted in-depth inspections on miles of other CA/T connector and main line tunnel sections, including the I-90 Westbound Connector Tunnel, Ramp B, Ramp L, Ramps D & DN, and Ramp RT.
The inspections originally focused on the ceiling panel anchorage support systems and quickly developed into the full inspection and assessment of all of the tunnel elements including the development, with EOT/MHD, of inspection procedures and specific inspection report forms to be used by all consultants. The Inspected items included ceiling panel hanger units, roof slabs, roadways and safety walk areas, tunnel finishes and false walls, slurry walls, wall and roadway plenums, and utilities.
Immediately following each inspection, DTC prepared report summaries and deficiency reports with recommendations for each deficient item. DTC is in the process of preparing formal inspection reports.
Projects
DTC, in conjunction with JCJ Architecture, is performing complete engineering services for the construction of a new Pre-K through eighth grade elementary school. Services include: environmental site investigation, analysis and remediation planning, site layout and vehicular circulation; landscaping and site lighting; extension and/or relocation of site utilities such as: water distribution, sanitary sewer system, storm sewer system and electric /communication/ cable television/ gas; permitting; structural design and HVAC and fire protection design.
DTC was contracted by the Town of Killingly to design a bridge replacement for a single span bridge over Slater Brook. The existing bridge was closed after an inspection revealed undermining and failure of one of the abutments. The newly constructed bridge consists of a precast arch spanning 12 feet over Slater Brook along with 20 foot high wing walls. DTC was also responsible for performing the hydraulic analysis and obtaining all permits required as part of the State’s Local Bridge Program.
This project, designed by DTC, is currently under construction and DTC is providing the Construction Phase Services. Funding is provided under the STP-Urban Program. The project involves replacing the existing two span concrete bridge with a single 80 foot span comprised of pre-stressed bulb-tee beams with a concrete deck supported by cantilevered abutments on concrete filled steel pipe piles. The bridge carries State Street over the Mill River, and one end of the bridge is under another bridge carrying Interstate 91. Two lanes of traffic must be maintained during the two stages of construction.
As a subconsultant to two firms, DTC has been providing tunnel and bridge inspection services on the following General Engineering Consulting Services Contracts: