Background
With a total distance of nearly five miles and at one point being named as the world's longest continuous over-water steel, the Chesapeake Bay Bridge is certainly a site to see. As a major outlet feeding the Baltimore-Washington DC metropolitan area which serves an estimated 61,000 vehicles daily, it’s also quite a site to maintain.
The company behind the structure’s construction and maintenance was working on bearing retrofits along the bridge’s columns. Rather than closing down lanes for several weeks, they had installed access platforms about 20 feet beneath where the bearing retrofit would take place at two locations.
The Problem
he access platform was the staging area for the project, with structural steel components, tools and other hardware coming from down below. With much of that material weighing several hundred pounds, they needed a way to lift the components from the access platform to the work area.
The Solution
The solution came in the form of 2 Gorbel articulating jib cranes, one for each of the identical work areas. The 1000 pound capacity jib cranes measure 14’ of overall span (8’ for the primary arm, 6’ for the secondary). The jib model used is a freestanding design, though it installed without a supporting column in order to flush mount on the side of the bridge. Because rigging restrictions prohibited any permanent impact on the existing structure, the jib was fixed on the edge of the bridge with squeeze plates securing it in place without penetrating the surface.