Some of the more famous and identifiable elements of New York City are its streets and bridges. Wall Street, the Brooklyn Bridge, Broadway and the George Washington Bridge all invoke images of different, yet distinct slices of the Big Apple. Unfortunately, descriptions of the streets and bridges themselves usually include “snarled by traffic” and “under repair.”
Such was the case with the venerable Queensborough Bridge, also known as the 59th Street Bridge, which soars over the East River to connect Queens and Manhattan.
Traffic congestion has been such a problem on New York’s East Side that in October 1996, city officials went so far as to alter traffic patterns around the mouth of the bridge. The city also recognized the need for the Queensborough Bridge itself to be rehabilitated.
A project as involved as working on one of New York City’s major bridges brought together two of the country’s largest contractors, the Grow-Tunnelling Co., a division of Kiewit Construction Group Inc. and the Perini Corp., to form the Grow-Perini joint venture. Each company has a wealth of experience and expertise in handling major construction and heavy highway projects, such as bridge and road work and tunneling projects.
“The project was divided into phases involving all five spans of the bridge,” said Victoria Klun, field engineer, Grow-Perini. “It called for the rehabilitation or removal and replacement of both the north and south outer roadways, which are cantilevered sections off the main trusses. The project also involved rehabilitating both the Queens and Manhattan surface approaches to the bridge.”
Need for special equipment
Grow-Perini knew it would need a wide array of equipment to complete the varied tasks of the project.
“To work on the two spans of the bridge over the river and the span over Roosevelt Island, we needed barge-mounted derrick cranes, crawler and truck cranes and other pieces of equipment,” Klun said. “But none of these were anything out of the ordinary. It wasn’t until we were about to begin work on the Manhattan approach that a unique situation arose.”
The Manhattan surface approach to the Queensborough bridge is approximately 700 ft long. Because the bridge was finished in 1908, the approach was originally designed for trolleys. Even now, the roadway still contained sections of trolley track, in between which ran an underground concrete trough containing the workings for the trolleys.
“According to specifications, the “trolley yoke”, as it is called, contained cast iron wiring conduit and lightweight fill and part of the work involved removing the entire contraption,” explained Klun. “We planned on shutting down both lanes of the approach in order to trench down 3 ft between the rails, remove the lightweight fill and workings and break up the concrete for removal.”
The day Grow-Perini was to shut down the two lanes of traffic, the city rephased the project so the coordinator would only be able to shut down one lane at a time.
“We had to regroup and figure out how to do this and what equipment to use now that we only had half the roadway,” Klun said. “We consulted Edward Ehrbar Inc., a Komatsu America distributor, for advice and they suggested the new Komatsu PC128UU hydraulic excavator.”
According to Komatsu, the PC128UU “ultra urban” excavator offers several unique features designed to increase productivity and safety while enabling it to operate in extremely tight working conditions. These features include an exclusive zero tail swing design, offset boom, unique over-center boom design, as well as an electronic control system for the boom’s height setting, offset positioning and digging depths.
“We were excited to show the unit to Grow-Perini when we learned of their situation on the Queensborough Bridge project,” said Chris Thompson, sales representative, Edward Ehrbar.
Grow-Perini agreed with Thompson’s assessment that the excavator would be the most productive piece of equipment for the job and rented the unit from Ehrbar for the duration of the Manhattan approach rehabilitation phase.
Hard work, tight quarters
Grow-Perini and Klun came up with an innovative system that enabled them to work efficiently within the 15 ft wide work area.
“We decided it wasn’t feasible or safe to back a dump truck into the work area, so we had a wheel loader following the PC128UU,” Klun explains. “With its over-center capabilities and zero tail-swing, we could lift or excavate with the PC128UU, turn completely around and load the bucket of the wheel loader. When it was full, the loader would back down the ramp and deposit the material into a dumpster.”
Many of the excavator’s innovative features came into play during work on the approach ramp. Not only was the work area narrow, but the work was taking place under the bridge itself.
“The control system for the boom height was a tremendous help,” Klun said. “We had to be conscious at all times of our surroundings, as there were drainage pipes and other elements running under the bridge deck. Using the height setting, we were able to avoid any contact with these elements.”
“The unit’s ease of handling contributed greatly to the safety of the work site,” she continued. “City busses could barely fit in the open lane and the only thing separating them from the work area were 12 x 12 timbers. Again, we could not risk any sort of contact and none occurred.”
Klun also said that the PC128UU’s off-set boom capabilities enabled maximum productivity in the confined work envelope by allowing the operators to dig to the side without having to turn the unit.
The PC128UU was designed to enhance productivity in tight working conditions, as well as be less intrusive in urban settings.
“In metropolitan areas like New York, there is a strong need for the PC128UU,” said Pat Ahern, executive vice president of Ehrbar. “Avoiding the implementation of extra lane closures while using a productive piece of equipment is a tremendous benefit for contractors.”