By: Michelle Breidenbach
Source: syracuse.com (TNS)
Have you seen the two giant bright yellow spider-like structures at the construction site on Interstate 481 over the CSX rail yard in DeWitt?
Plenty of cars are slowing down to gawk at the 3-story tall structures. They’re so big they had to be assembled on site.
They are called gantry cranes – the kinds of machines usually seen at rail and shipping yards. They can lift a shipping container.
The two gantry cranes on I-481 are an engineering solution to a tricky construction dilemma.
Picture two existing 2,100-foot long bridges side-by-side over a functioning railroad. The northbound and southbound bridges are separate structures with a little space in between.
Contractors are adding one lane to each side. And they are building those new lanes in the space in the middle.
There is not a lot of room to maneuver construction equipment in between two bridges, said Jim Harmon, the DOT’s engineer in charge.
Enter the gantry cranes. These cranes have wheels taller than a person. Two cranes will roll over the lanes with one wheel on each existing bridge. In their giant hooks, they will carry the heavy steel beams needed to support 15 spans of new bridge deck.
“It’s very tight down in the middle where the cranes would have to sit to set the beams, so these cranes carry the load differently than a traditional crane,” Harmon said.
The cranes will roll back and forth with 60 beams over the next six or eight months, he said. Each beam weighs 68,000 pounds - about the weight of 19 Suburu Outbacks.
It took about a week for workers to haul in the crane parts and build them on site, he said. It took another week for operators to learn how to run the cranes in this unusual configuration, he said.
There are other advantages to this. Using cranes to walk the beams into place above the bridges also means construction does not touch wetlands or the railroad lines below.
The work is part of the massive project to tear down the elevated Interstate 81 in downtown Syracuse and build up I-481 to handle more high-speed traffic around the east side of the city.
The idea came from staff for CNY Alliance, the contractors on this section of the project, said TeNesha Murphy, spokeswoman for the DOT. The contract for this stretch of the highway project is a “design-build” contract, which means the DOT lays out a plan and the contractors have a big say in designing it.
Drivers will continue to have a close-up view. Traffic will continue to flow on two lanes north and south during construction.
Contact Michelle Breidenbach | [email protected] | 315-470-3186.
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