A busy expressway tunnel in Yamanashi Prefecture partially reopened Saturday to ease congestion in the area after the ceiling of the Tokyo-bound side collapsed earlier in the month, killing nine people.

Because the outbound side of the damaged Sasago Tunnel is a two-lane artery as well, Central Nippon Expressway Co. converted it for use in both directions as a stopgap measure after removing the ceiling tiles in the outbound tunnel.

The speed limit is 40 kph in the tunnel and 50 kph outside it, the company said. Since the heavily used Chuo Expressway links the capital with central Japan, the tunnel accident disrupted delivery services and tour bus runs, and is also expected to delay holiday travelers.

Central Nippon is predicting traffic jams as long as 45 km will form at the tunnel Wednesday, when New Year's traffic is expected to peak. At that rate, it could take as long as 4½ hours to clear the tunnel, it warned.

To mitigate the congestion, the company will open an alternate route Tuesday to circumvent the tunnel, which is just west of the city of Otsuki. The alternate route will likely make use of the 23.5-km Fujiyoshida Line, which branches off southward from the main Chuo Expressway to the city of Fujiyoshida, where national highways closer to Mount Fuji can be used.