Owner: Vermont Agency of Transportation & Town of Middlebury, VT
Engineer of Record: VHB
Contractor: Kubricky Construction Corp. (Wilton, NY)
Precast Concrete Manufacturer: The Fort Miller Co., Inc. (Greenwich, NY)
Administered through a Construction Manager / General Contractor (CM/GC) contract by The Vermont Agency of Transportation and Town of Middlebury, two nearly 100 year old bridges over railroad tracks are being replaced by a 345-foot long precast concrete tunnel, which is part of a 1,736-foot long precast concrete rail trench in the center of Middlebury, Vermont. In 2017, the two bridges were removed due to severe deterioration and temporary bridges were installed to maintain traffic. According to a VTrans report, the bridges did not have enough vertical clearance for double-stack rail cars. This project lowers the vertical rail bed for more than 3,000 linear feet, thus allowing vertical clearance to be extended from less than 18 feet to 21 feet without impacting final grade of the streets and sidewalks above. Lastly, the new tunnel and trench improves the rail alignment by reducing a sharp horizontal curve.
Fast forward to 2019 when The Fort Miller Co., Inc. (Greenwich, NY) commenced fabrication on 423 total precast concrete elements; 295 U-Wall sections and 127 Upper-Wall units. The heaviest U-Wall pieces weigh approximately 80,000 pounds and the average weight of the precast is approximately 70,000 pounds. The completed 4-sided tunnel section will be 17’-9” wide and 24’-4” high (inside dimensions). Installation of the precast began in mid-July by the general contractor, Kubricky Construction Corp. (Wilton, NY). An aggressive 10-week construction / installation schedule is planned to be completed in late September.
