Down by the riverside

On average, more than 40,000 vessels, 900,000 passengers, and 200,000 tons of cargo pass through the gates of Chicago’s Harbor Lock each year, and the lock itself opens and closes 11,500 times yearly. But the 72- year-old Harbor Lock on Lake Michigan at the mouth of the Chicago River, owned and operated by the U.S. Army Corps of Engineers, has been deteriorating for the last 15 years. The lock gates have been leaking, and 10 gate breakdowns have occurred since 1991. Finally, new lock gates are being installed as part of a major overhaul to keep all that traffic moving.

The lock replacement project is being handled by general contactor James McHugh Construction, who hired Central Contractors Service of Chicago, a member of the ALL Erection & Crane Rental Corp. Family of Companies, to provide the lifting power to get the new gates in place. So how do you get a crane to a job site out on the water? Mount it on a barge.

Central’s decades of experience in lift planning made it easier to select the proper equipment. They recommended their 300t-capacity Manitowoc 4100W S-3 Ringer crane with a 140-foot boom, a total picking radius of approximately 72 feet, and a capacity-enhancing ringer attachment. There were several larger Manitowoc cranes to choose from, but Central felt that the 4100W S-3 Ringer was the most economical and would allow for better distribution of the point loading.

What does a ringer attachment do? John Martello, Central Contractors Service General manager, explains, “When a crane must be mounted on a barge, the crane’s load charts are decreased because of the lack of a reverse force; in other words, a barge is floating on water, not set on firm land. The relative instability of a floating platform has a negating effect on the operator’s ability to pick the load weight. Adding a ringer and pedestals to a crane distributes loading over a larger area and can increase the lifting capacity dramatically. The ringer attachment on the 4100W was utilized to better spread the weight of the crane on the surface of the barge. Instead of all the weight of the crane being carried on just two tracks, the weight is distributed to 11 points. This allows point loads to be reduced.”

The Manitowoc 4100W S-3 Ringer was erected on the barge at the Iroquois Landing dockside facility in Chicago, Ill. The newly-fabricated gates, with a total weight of 180,000 pounds, were loaded up and the barge was towed by tugboat to Navy Pier, a trip of three hours. The lift and installation of the first gate took place on December 2, 2010, and the second gate took place a week later, on December 9. Both procedures went without a hitch. Central’s crane operator, Ken Derry, says that the U.S. Army Corps of Engineers was impressed with the crane and the operation. “USACE required that the maximum list of the barge during the gate picks be no more than 2%. The actual list during the pick was 0.00%. This number is amazing, considering the weight of the pick and its location on the water almost 90 feet away from the crane.”

The barge and crane were repositioned for setting the final two gates in mid- January.