The more the merrier, and with just four hours available to complete a bridge demolition, Staker Parson Cos. used a total of six processing attachments to get the job done on a tight schedule.
The Ogden, Utah-based demolition crew was commissioned by contractor Kiewit Infrastructure Group, Littleton, Colorado, to tear down and replace Denver’s Pecos Street Bridge over Interstate 70. The structurally deficient and poorly rated bridge extended 156 feet with a single span post-tensioned concrete box girder design.
With more than 130,000 vehicles crossing the bridge daily, the Colorado Department of Transportation (CDOT) chose an accelerated bridge construction (ABC) approach to minimize interference with traffic flow. The $18 million project included replacing the Pecos structure; installing roundabout intersections; and building a pedestrian bridge structure that spanned I-70, according to CDOT.
Crews constructed the replacement bridge in the bridge staging area about 800 feet away from the final bridge location and moved it into place on tracked material handlers.
The demolition crew initially had eight hours to bring the old bridge down; after being tasked with leveling the dirt ground so that the excavators had a smooth space to work on, Staker Parson Cos. had only four hours left to demolish the bridge, says Kevin Loomis, business line manager, construction tools, for Atlas Copco Construction Equipment, Commerce City, Colorado.
Equipped with four Atlas Copco hydraulic breakers and two hydraulic Atlas Copco’s CC 3300 Combi Cutters, the crew finished by deadline and with minimal cleanup, opening the bridge to traffic on schedule, Loomis says.
He explains of the demolition, “The Combi Cutters and breakers started in the middle of the bridge and worked outwards. As the breakers struck rebar, the cutters came over, sheared through the bars and moved to the next spot.”
The Pecos Street Bridge demolition, using hydraulic breakers and cutters, is just one example of how working with job-specific processing attachments can serve efficiently and effectively in demolition and recycling applications.
Location, location, location
Roland Jarl, vice president of the EEI Group, Mahwah, New Jersey, says contractors should always do some research before beginning a project.
When the Colorado Department of Transportation (CDOT) decided the structurally deficient and poor-rated Denver Pecos Street Bridge over Interstate 70 needed replaced, the bridge department chose the accelerated bridge construction (ABC) approach. The CDOT said the ABC approach for the 156-foot-long bridge, with more than 130,000 vehicles crossing it daily, would help to minimize construction impacts to the travelling public.
The $18 million project included replacing the standing Pecos structure; installing roundabout-type intersections; and building a pedestrian bridge structure that spanned I-70, according to CDOT.
To accomplish the demolition in a manner that minimized interference with traffic flow, CDOT officials said the ABC path also would help to manage costs.
According to the U.S. Department of Transportation Federal Highway Administration, ABC is “a paradigm shift in the project planning and procurement approach where the need to minimize mobility impacts that occur due to on-site construction activities are elevated to a higher priority.” ABC uses innovative planning, design, materials and construction methods in a safe and cost-effective manner to reduce the on-site construction time that occurs when building new bridges or replacing and rehabilitating existing bridges, says the Federal Highway Administration, on its website www.fhwa.dot.gov.
The Federal Highway Administration lists benefits of the ABC approach, including improvements in:
“You should look at the job site before you start the job to see what kind of limitations you’re going to have,” Jarl advises. Restrictions can include a nearby bridge or the size and weight of equipment permitted on site.
According to Ryan Murphy, director of marketing for Indeco North America, Milford, Connecticut, it is important to know the regulations in the area the work is being performed. Indeco provides heavy-duty hydraulic breakers, compactors, crushers and pedestal booms for demolition, mining, recycling and road construction applications. Murphy says understanding the scope of an entire project will help contractors decide which attachment is best for their operations.
Equipment providers also agree that noise is another job site constraint to consider. If the project is located in an urban area, such as a high-rise or business block, contractors need to minimize noise and vibration that cause disruptions. Selecting the proper attachment in an urban setting is of utmost importance, according Loomis.
“Strong vibrations and loud noises could disturb hospital patients or interrupt teachers in a nearby school,” Loomis explains. “The hydraulic attachments are quieter and more efficient alternatives to pneumatic tools because they don’t use air compressors to create mechanical power.”
Many attachments also have slim profiles for “precise, selective demolition,” Loomis describes.
For smaller or tighter work spaces, Jarl says multiprocessors are ideal. Multiprocessors use interchangeable jaw sets to do the work of numerous demolition tools, allowing a single unit to crush, pulverize and perform a variety of specialized cutting tasks, including cutting steel rebar and tanks.
Jarl explains, “The multipurpose tool would be preferable to use [in some instances] because of limited space, and it’s only one piece of equipment rather than two or three.”
The versatility of multiprocessors allows operators to switch from a crusher pulverizer to a shear to get the job done more efficiently, Jarl notes.
The multipurpose tool does cut down on pieces of equipment required, however, it might not be the best tool for many jobs, according to Murphy.
“While you can buy a multipurpose attachment, it is never the best attachment,” Murphy states. “Multipurpose in concrete is going to work, but it’s never going to work at the speed and productivity as a dedicated steel attachment.”
He calls the multitool the “Swiss army knife” of attachments.
While multipurpose attachments can be used in various demolition and recycling applications, Murphy says an attachment dedicated to pulverizing one material will outperform a multiprocessor capable of processing a number of materials, indicating the importance of the on-site material.
“The type of material on site is largely going to determine what the configuration of your attachment will be,” Murphy explains. “If you’re pulverizing a concrete structure, you’re not going in there with a steel shear.”
There are specific attachments for each material, he says. From downsizing material such as concrete to processing wood for recycling, attachments are all about productibility, Murphy notes.
As Loomis describes, Atlas Copco’s Combi Cutter cuts and crushes concrete and steel while pulverizers handle reinforced concrete demolition and material separation. Both of these attachments make steel cutting faster and safer than acetylene torches, which add fire and explosion hazards to work sites, he says.
The company’s Demolition Pulverizer attachments eat through rebar and concrete with up to a 350-ton cutting force and a 110-ton crushing force, Loomis says.
Drum cutters, which are becoming increasingly popular in demolition applications, Loomis says, create a uniform surface by grinding off only the surface of the concrete, rather than all of it.
Atlas’ Hydro Magnets use onboard, hydraulically driven generators to energize the magnet to attract up to 16,535 pounds of ferrous metals, Loomis says.
Stanley LaBounty, based in Two Harbors, Minnesota, is another manufacturer of demolition and recycling tools. It offers a full line of mobile shears for steel and concrete demolition; concrete demolition attachments designed for primary and secondary demolition; and various types of grapples for demolition and material handling. Its attachments are designed for the demolition and recycling of ferrous and nonferrous steel and concrete.
Despite challenges contractors might run into regarding material handling, a company’s existing fleet of equipment is another limiting factor when choosing the appropriate attachment, Murphy says.
“What a contractor has for machinery, tool carriers, excavators—that’s going to determine what attachment he’s buying,” Murphy says.
He continues, “I can’t sell a shear for a 45,000-ton excavator if the largest excavator [the operator] has is a 20-ton; he’ll just tip over.”
Finding attachments that fit the company’s excavator’s weight range also is important for productivity and safety, Loomis says.
As Greg Smith, marketing communications manager for Allied Construction Products, Cleveland, describes, “The size of the excavator largely determines what attachment should be used. If the hammer and excavator are not sized to each other, there is a major safety concern as well as potential damage to both the excavator and the attachment.”
Sometimes an operator might not realize the advantages of incorporating different attachments into the company’s fleet of equipment.
That was the case for a contractor based in Connecticut, according to Murphy.
Murphy says this particular contractor had never owned a concrete processing attachment. He explains how the contractor, when faced with a large concrete demolition project, would hire a company equipped with a portable crushing plant to crush the material on site.
That changed after a demolition job the contractor had in Bridgeport. “He estimated he was going to have to sell the crusher for about three weeks,” Murphy says, adding, “We introduced him to our IFP 1250 concrete pulverizer attachment, and by taking the building down and pulverizing on the ground he ended up keeping the crusher for just four days.”
The Connecticut contractor saved “tens of thousands of dollars” on one project by integrating processing attachments into his operations, Murphy says. He has since purchased the initial concrete pulverizer and a steel shear from Indeco, Murphy reports.
The author is associate editor of Construction & Demolition Recycling and can be reached at firstname.lastname@example.org.