$45 million 1.7 km-long cut-and-cover Weserauen bypass tunnel alongside River Weser is 10.5 m below water level at lowest point. Excavation is supported by 57,000 sq m of back-anchored sheet piling behind which 460,000 cu m of soil is being removed for reprocessing as gravel and top cover. Base comprising 55,000 cu m of concrete will be placed under water in 50 sections and secured from flotation by 3,500 vibrated injection piles up to 14 m-long. Road will be two lanes in either direction in tubes 21 m-wide x 7.2 m-high, with floor, outer walls and roof up to 1.1 m-thick and internal wall 600 mm-thick, erected at 15 m/week. Contractors are Bilfinger & Berger. Visit www.bilfingerberger.de Sept 2000.
