Link-Belt crawlers put to work at New Hampshire bridge19 July 2017 by Sotiris Kanaris
New Hampshire- based R.S. Audley has used two Link-Belt lattice crawlers for the replacement of four northbound lanes on the Little Bay Bridge.
The Little Bay Bridge, is a nine-span steel girder bridge that over the Piscataqua River in southeast New Hampshire. It carries well over 70,000 vehicles each day and is forecasted to carry 94,000 vehicles by 2025.
In order to complete the project, R.S. Audley had to remove over three million pounds of old 1960’s era steel using several cranes from their fleet, including a Link-Belt 110USt 218 HSL lattice crawler crane.
By mid-2016, the replacement of steel for the refurbished northbound lanes of the bridge had begun. Steel erection was done by working from both ends of the new 1,589ft (484m) bridge structure to the centre, five girders across with diaphragms connecting and strengthening the superstructure over the existing piers.
To complete the final steel work R.S. Audley purchased a new 150USt Link-Belt 238 HSL lattice crawler crane and rented a 250USt 298 HSL from Link-Belt distributor, Wood’s CRW.
One of the most difficult elements to the steel replacement was the wind gusting up the bay from the Atlantic Ocean. For lifts toward the centre of the bridge, both Link-Belt cranes were used in the early morning before winds picked up – one crane for each 100ft beam.
The 155ft long centre beams weighed 78,000lbs each. The cranes lifted in unison and the beams were adjoined in the middle to form the centre span. Steel diaphragms were installed the rest of the day to space the beams alongside each other.
Scott Stevens, vice president at R.S Audley, said: “Aside from the wind, the 3% grade change coming up the bridge is something else to take into consideration, you must adjust each pick point a little bit to make sure the beam is hanging correctly for final placement. Using two 25USt Crosby beam clamps, the operator is able to reach out to the predetermined point, make sure it’s hanging correctly, pick it up and swing it out into position and marry it up to the previously set field splice.”
In order to work up and down the bridge deck meant R.S. Audley only had the working space of two lanes at a time, which was 28ft wide, to operate the two Link-Belt cranes. The new span went five girders across with diaphragms connecting and strengthening the superstructure over existing piers.
“The only weight restriction we had was keeping the “moving” load of our cranes down below 300,000 lbs. We were able to do this by removing counterweights as necessary during travel between pick locations. The stacked counterweights of the 238 and 298 made this a simple and straightforward process,” said Stevens.