LINKING UP THE LIVERPOOL LOOP

THE CONSTRUCTION OF AN UNDERGROUND RAIL NETWORK LINKING FOUR STATIONS IN LIVERPOOL IS DESCRIBED. THE EXTENSION OF EXISTING RAIL SERVICES IS AIMED AT REDUCING THE CONGESTION IN LIVERPOOL'S CENTER CITY. LARGE CAR PARKS ARE TO BE PROVIDED AT STATIONS TO ENCOURAGE PEOPLE TO TRAVEL INTO THE CITY BY TRAIN. THE LOOP AND LINK TUNNELS WERE DRIVEN THROUGH SANDSTONE, WHICH VARIES IN COMPRESSIVE STRENGTH FROM 5-28 MN/M2. MODIFICATIONS TO THE DOSCO TUNNELER USED ARE DESCRIBED. COLLIERY ARCH GIRDERS SUPPORT THE WEAKER SANDSTONE AND IN-SITU CONCRETE LINING WAS USED. SPRAYED CONCRETE LINING WAS SUITABLE FOR THE STRONGER SANDSTONE. IN THE STATIONS THE 7.5M TUNNEL HAS EXTENSIVE RIB SUPPORT. CONSTRUCTION DETAILS OF THE 5.1M EXTERNAL DIAMETER TUNNELS FOR THE 1.8 KM LINK ARE GIVEN. THE DOWNLINE TUNNEL PASSES THROUGH A DISUSED TUNNEL, WHICH WAS FILLED WITH CONCRETE AFTER THE SHAPE OF THE NEW UPLINE TUNNEL HAD BEEN FORMED IN POLYSTYRENE. THE CONTRACT IS SCHEDULED FOR COMPLETION IN DECEMBER 1976.