See link below on best explanation on fundamental problem. IMO
Relatives of Milena Mora Vargas Delvalle, of Costa Rica, who was killed when concrete ceiling panels fell onto her car in one of Boston's Big Dig tunnels late Monday night, attend the Morales funeral in Moravia, Wednesday July 19, 2006 in Costa Rica. (AP Photo/Cristobal Herrera)
The old style ceiling bolt in a Big Dig tunnel is seen on the left and the replacement style on the right, as workers make repairs and upgrades to a tunnel in the Big Dig project, Tuesday, July 18, 2006, in Boston. Two Big Dig tunnels were closed for inspections and repairs after 12 tons of ceiling panels fell, killing 38-year-old Milena Del Valle as she and her husband drove through the tunnel July 10 on their way to the airport. (AP Photo/David L Ryan, Pool)
A woman stands next to a portion of the ceiling which collapsed on a car inside the Big Dig tunnel on Interstate 90 killing a woman in South Boston, July 11, 2006. (Jessica Rinaldi/Reuters)