When the predetermined hour finally arrived to set the two arch sections, nearly eight months of planning came down to 60 minutes. The LTM 1450 was configured with 156 ft of main boom at a 45-ft radius with 295,000 lb of counterweight. The LTM 1250 had 119 ft of main boom at a 30-ft radius and 214,000 lb of counterweight.
In the days preceding, both cranes had already been quite busy. The two 125-ft bridge spans were set on their respective abutments and temporary structures toward the middle, as well as a 250-ft center span resting on the temporary structures. By installing the arch, which would assume the bulk of structural support duties for the entire bridge, the temporary structures below could be removed and the bridge would be essentially complete.
With the clock running, crane operators held each arch piece in position as a dozen ironworkers, six in man lifts and six on the ground, swarmed the area to install scores of bolts at critical splice points. There was a minimum number of bolts that had to be installed for the structure to support its own weight, and this became a crucial milestone. It meant that, should the work window start to close, the bridge would be stable enough to stand on its own. Otherwise, if the milestone was not met, ironworkers would have to reverse course and disassemble the arch so they could try again another day. Given the difficulty in scheduling work windows, no one wanted this.
At the 35-minute mark, when the threshold was reached, everyone breathed a sigh of relief. Just 23 minutes later, at minute 58, the work was completed. There would be no need to schedule a second work window. The new hiking and biking bridge was now a reality.
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Editor's Note: Scranton Gillette Communications and the SGC Infrastructure Group are not liable for the accuracy, efficacy and validity of the claims made in this piece. The views expressed in this content do not reflect the position of the Roads & Bridges' Editorial Team.