When the removal of a bridge over busy I-95 in Fort Lauderdale, Florida, was deemed necessary to widen the interstate highway’s lanes, construction managers from Archer Western and De Moya Group initially envisioned a two-stage demolition process requiring 30 days.
Instead, heavy lifting and transportation contractor Mammoet came up with an alternative plan that involved shutting down the highway for just eight hours overnight, lifting the 1,082-ton bridge span from its moorings and transporting it south along I-95 to an offramp for demolition.
Six trains of eight-line self-propelled modular transporters equipped with 250-ton jacks hoisted the bridge off its abutments in May for relocation south along I-95 to an offramp for demolition. This approach took just three hours, reducing disruption to traffic by several weeks' time.
Mammoet's use of its Accelerated Bridge Construction (ABC) method not only slashed the project schedule, but sidestepped the safety risk of having crews conduct demolition work while traffic moved below.
The removal of the State Road 94 bridge represented part of the I-95 Express Lanes Phase 3C project, intended to enable lanes below the bridge to be widened and efficiency of the SR 84 interchange enhanced. Reconstruction of the westbound SR 84 bridge will be undertaken after the lane-widening and interchange improvement work's completion.
According to Charlie Fernandes, market development manager for Mammoet, the project involved more than one challenge. A quick turnaround between the time the ABC plan was greenlit and its execution represented the first obstacle.
"We had final drawings [and] an execution plan all approved and on site within three weeks notification," he said. "An additional challenge was the traffic detour itself. Even though Mammoet did not have any scope in this, it was a big deal for DOT to close down one of the busiest interstates in the country for a short window of only eight hours."
Because Mammoet removed the bridge in a three-hour time frame — less than half the time allotted for lane closures — the team was able to reopen lanes earlier than planned, he said.
According to the Federal Highway Administration, ABC technologies are changing the ways state DOTs operate. Most notably, DOTs can replace bridges within 48 to 72 hours and reduce planning and bridge construction efforts by years, the agency says.
In addition, ABC planning and construction methods, designs and materials produce safer, more durable bridges with longer service lives than conventional bridges, according to FHWA.
Safety and collaboration
The challenges on the Fort Lauderdale project were surmounted through "great teamwork and communication," Fernandes said. Mammoet's operations team, led by project manager James Butler, arranged for delivery of all required components as well as the equipment mobilization and crew needed for the assembly of equipment.
Crews employed Mammoet's safety policy, called Mammoet Minute, that encourages employees to take a last-minute risk assessment to evaluate and control risks before work begins each day.
"Our field execution team always puts safety first while working next to the open traffic roadway," Fernandes said. "We utilized our Mammoet Minute to take the time, use the right tools and have spotters all working together to ensure a safe, on-time delivery."
This article first appeared in Construction Dive: Infrastructure, a new weekly publication from Construction Dive. Click here to have it sent straight to your inbox.