The Sunday collapse of a portion of the ceiling of the Sasago Tunnel on the Chuo Expressway in Yamanashi Prefecture, crushing three vehicles and killing at least nine people, has raised serious and widespread concern about the safety of road tunnels throughout Japan. This accident clearly was caused by human neglect.

Inside the 4.7 km-long tunnel, some 180 concrete panels forming a length of the tunnel ceiling fell, covering a distance of some 130 meters. Each panel is 5 meters long, 1.2 meters wide, 8 cm thick and weighs 1.2 tons. At the very least, expressway companies and the central and local governments must carry out thorough inspections of the reported 48 other tunnels that share the same design as the Sasago Tunnel to prevent similar accidents.

The Sasago Tunnel features an older ventilation system called transverse ventilation that utilizes ceiling panels to circulate air by bisecting the upper half of the tunnel. Two rows of ceiling panels are attached to either side of the tunnel wall and to 5.3-meter-long metal rods that are fastened to the tunnel roof by bolts at 1.2-meter intervals. The bolts are not threaded into the tunnel roof but rather attached by metal glue. It is suspected that the bolts anchoring the metal rods failed, causing the ceiling panels to collapse. Some bolts were found to have fallen from the tunnel roof.