Five of eight rope-dog tower beams up

The photos at left and below illustrate the complexity of building a 110-foot tall rope-dog tower inside an even taller building?the Yates Shaft headframe. For example, sheeting and windows must be removed at several locations so cranes can poke inside to position the tower?s large structural beams.

Project Engineer Mike Johnson reports today that five of the eight steel beams of the tower?s vertical structure have been set in place. One beam remains to be installed on the south side of the headframe; two beams await installation on the north side.

After the vertical beams are installed, contractor Heavy Constructors Inc. will install a horizontal structure at the top of the tower, which will include two 1,100-pound ?rope glands.? Glands are self-locking wedges that will secure the dog ropes to the tower.

The rope-dog tower is scheduled for completion later this month. Then a Sanford Lab crew will hang the dog ropes that will run the length of the 5,000-foot shaft. The ?ropes,? by the way, are braided steel wires. The ?dogs? are clamps that will automatically grip the ropes, stopping the service cage in the unlikely event of a hoist-rope failure.

In April, after the rope-dog system has been tested, the Yates Shaft will become the main entry route to the underground. The Ross Shaft will provide secondary egress.