Construction of Sasago Tunnel is being blamed on use of ` ` anchor . '' The bolts attached concrete blocks to the ceiling of the tunnel . Two people died when concrete slabs fell on traffic on Sunday morning . Japanese highway police said Monday the section of concrete that fell was 110 meters ( 360 feet ) long . Forty - nine other tunnels of similar construction are being inspected across Japan .
Construction of Sasago Tunnel is being blamed on use of ` ` anchor . '' The bolts attached concrete blocks to the ceiling of the tunnel . Two people died when concrete slabs fell on traffic on Sunday morning . Forty - nine other tunnels of similar construction are being inspected across Japan .