The goal of this project was to replace two structurally deficient pipe culverts that carry Lubbers Brook beneath Middlesex Avenue (Route 62) in Wilmington. The two pipes and adjoining headwalls were constructed in 1960. The culvert barrels had begun to fail, with sinkholes opening within the roadway above the top of the culverts. Due to the skew of the brook to the roadway and the sensitive environmental areas on each side of the road, the design team settled on a corrugated metal arch culvert with cast-in-place concrete headwalls and wingwalls.
A key concern regarding this project was traffic flow. Middlesex Avenue, which sees about 26,000 vehicles a day and is essential for first responders, cuts through the heart of Wilmington and connects commuters with local destinations as well as I-93 and the North Wilmington MBTA station. Early in the project, the team looked for ways to stage the project to always allow for at least one lane of through traffic. However, due to the large excavations required, environmentally sensitive land upstream and downstream, and the presence of obstructions found when doing early geotechnical investigation, these approaches were deemed to be unfeasible.
Therefore, the design team then pivoted and focused on ways to reduce the closure time as much as possible. These efforts were hampered to an extent due to the large 52° skew which precluded the use of a precast concrete culvert or a precast headwall. Options for design were further limited by the adjacent homes, businesses, and MBTA Commuter Rail line that was approximately 500 feet from the western end of the project.
Accounting for these design constraints, the solution proposed by the design team consisted of a full closure for 30 days. This would be followed by a 42-day period of single lane, alternating flow traffic, controlled by a temporary signal. At the end of the 42-day closure, two lanes of traffic and a single pedestrian access route would be available to the traveling public while the Contractor continued to work in the shoulder areas.
Once the contract was awarded, several residents of the Town of Wilmington and the Town of Wilmington Emergency Services personnel began to grow concerned about the 42-day single lane closure. There was concern that traffic at the temporary signal could backup on to the adjacent MBTA commuter rail line. The Contractor (J. Tropeano Inc.) proposed a different solution that utilized a 44 day full closure, but at the completion of 44 days, two-lane traffic would be open on Middlesex Avenue. This solution was accepted by the Town and a full closure was implemented on July 18.
Through hard work and close collaboration from all members of the project team, the road was opened to traffic at 5:00PM on August 30. As a result, all buses were able to cross the new structure the next morning and deliver their passengers to their first day of school!
