| Study initiated immediately after 1989 earthquake. Need to retrofit for earthquakes of Richter magnitude 7 or above. Phase 1 1997-2002 – strengthening together with installing of isolator bearings, expansion joints. 4 support towers replaced during continuous traffic flow. Phase 2 2001-2008 – replacing support towers, anchorage housing plus new shear walls, installing isolation bearings and joints, adding new steel plating, new bearings and energy dissipation devices and isolation joints. Phase 3 2008-2012 – strengthening foundations, installing piles and rock bolts, shear walls and other structural modifications. | 