This was mostly an unlined natural rock tunnel with 33 feet at the north end of the tunnel being supported by timber sets. This line carries single mainline track in a north/south direction. The tunnel is approximately 428 feet long, 20 feet wide, and 25 feet tall. The primary problem was a freeze-thaw degradation that caused the natural bedrock and timber sets to delaminate, separate and spall.
LRL was contacted to repair the problem area. This consisted of hand scaling the north approach cut and north portal area by rail-mounted equipment, removing 12 timber sets, installing a total of 1,352 liner feet of fully grouted rockbolts, and applying a 6-inch-thick layer of fiber reinforced shotcrete around the north portal area and 33 feet into the tunnel at the north end. A total of 48 cubic yards of shotcrete was applied along the northern portion of the tunnel.
This work was performed on schedule and in budget.
