(right)
The Anton Anderson Memorial Tunnel was originally constructed as a railroad tunnel during World War II. (See the Project History page of this website for more information.) During the winter of 1998-1999, the rail ties and ballast were removed and replaced with a concrete driving surface. The driving surface consists of 7.5-foot-long and 8-foot-wide precast concrete panels placed on a bed of crushed rock. Cast-in-place concrete was placed adjacent to the concrete panels to form an 11.5-foot-wide paved surface. Notches in the panels allow the rail to be placed flush with the surface. Asphalt was placed adjacent to the rail to provide easy access to repair the rail. Approximately 610 feet of the tunnel is lined with corrugated steel plates to control drainage and icing in the winter. Approximately 2 miles of the tunnel has chain link mesh pinned to the crown of the tunnel to catch any loose rocks. The rest of the tunnel is reinforced by concrete sprayed (shotcrete) on the crown. The majority of the rock in the tunnel is very strong and stable. During the 1964 Good Friday Earthquake (the greatest magnitude earthquake ever recorded in North America) the tunnel suffered no significant structural damage and no cave-ins.
http://tunnel.alaska.gov/virtualdrive.shtml
The Anton Anderson Memorial Tunnel was originally constructed as a railroad tunnel during World War II. (See the Project History page of this website for more information.) During the winter of 1998-1999, the rail ties and ballast were removed and replaced with a concrete driving surface. The driving surface consists of 7.5-foot-long and 8-foot-wide precast concrete panels placed on a bed of crushed rock. Cast-in-place concrete was placed adjacent to the concrete panels to form an 11.5-foot-wide paved surface. Notches in the panels allow the rail to be placed flush with the surface. Asphalt was placed adjacent to the rail to provide easy access to repair the rail. Approximately 610 feet of the tunnel is lined with corrugated steel plates to control drainage and icing in the winter. Approximately 2 miles of the tunnel has chain link mesh pinned to the crown of the tunnel to catch any loose rocks. The rest of the tunnel is reinforced by concrete sprayed (shotcrete) on the crown. The majority of the rock in the tunnel is very strong and stable. During the 1964 Good Friday Earthquake (the greatest magnitude earthquake ever recorded in North America) the tunnel suffered no significant structural damage and no cave-ins.
http://tunnel.alaska.gov/virtualdrive.shtml