Minneapolis Southwest LRT: Design Chal lenges of Cut-and-Cover Tunnel Construc tion in Urban Area
The Southwest Light Rail Transit (LRT) (METRO Green Line Extension) Project is a proposed extension of the METRO Green Line (Central Corridor LRT) that would operate from downtown Minneapolis through the communities of St. Louis Park, Hopkins, Minnetonka, and Eden Prairie, passing in close proximity to Edina. The proposed alignment includes 16 new stations (including one that has been deferred for building out at a later date) and approximately 14.5 miles of double track. The project consists of two double-cell cast-in-place concrete tunnels. Both tunnels will be constructed by cut-and-cover method. The shorter tunnel is approximately 600 feet long and passes under Highway 62. The longer tunnel is approximately 2,200 feet long, runs adjacent to residential buildings and a freight rail and passes under Cedar Lake Parkway. This paper discusses the tunnel design considerations including an innovative support of excavation design to allow installation adjacent to the existing buildings and control of groundwater inflow during construction.Cut and cover tunnels, Southwest LRT.