Washington state regulators formally opened a probe into the companies involved in dismantling a crane that collapsed Saturday in South Lake Union, killing four people, as they began piecing together how the towering mast came crashing down on Google’s new campus and one of the city’s busiest thoroughfares.
The tower crane, a massive piece of equipment that has become a feature of Seattle’s skyline, was being dismantled when it fell around 3:30 p.m. Saturday, smashing the building and pinning several vehicles below on Mercer Street. Among those killed were a Seattle Pacific University freshman and two ironworkers. A day later, questions remained unanswered about what role a rising wind may have played and the decision not to restrict cars on heavily trafficked Mercer Street.
The notoriously gridlocked thoroughfare, which carries about 60,000 vehicles on an average weekday, reopened early Monday morning, as did the Interstate 5 ramps connected to it, the Seattle Department of Transportation said. City streets in the area that had been closed over the weekend also reopened in time for the Monday morning commute.
The following video shows the fatal April 27, 2019, crane collapse from a dashboard camera and contains explicit language.
The Washington Department of Labor and Industries said it had opened investigations with four companies involved in taking apart the crane. That work ranged from unfastening the bolts that held the crane together to removing each massive section using a second, smaller crane. Two of L&I’s crane investigators remained on the scene late Sunday, while officials began the process of interviewing companies involved and gathering records from them.
“Our goal is to pick this apart and understand what happened,” said Tim Church, a spokesman for L&I. He added that opening probes into individual companies is part of the investigation process and not a sign of any wrongdoing at this stage and that the investigation would take months.
The project, a new Google campus at Mercer Street and Fairview Avenue North, is being developed by Vulcan Real Estate. Investigators are seeking information from four companies, according to L&I: GLY Construction, the general contractor; Northwest Tower Crane Service, a subcontractor that physically disassembled the crane into pieces; Omega Morgan, which removed sections with a smaller crane; and Morrow Equipment, which owned the tower crane.
“We are deeply saddened and heartbroken by what happened at our job site,” GLY said in a statement Sunday. The company said it was cooperating with authorities in investigating the accident. The other three companies didn’t respond or could not be reached for comment Sunday.
L&I manages a certification and inspection program spurred by a deadly crane collapse in Bellevue in 2006.
A tower crane, the largest of its kind, is brought to a construction site in pieces and assembled there. It has to be inspected each time it is set up by third-party inspectors who are accredited by the state, according to L&I.
Portions of Valley Street and Boren Avenue North were closed Saturday as the crane was being dismantled, Seattle Department of Transportation (SDOT) Director Sam Zimbabwe said during a news conference Sunday.
“That was the footprint to load in and load out and do the work that the contractor had underway,” he said.
He said SDOT reviews plans for street closures due to construction work like crane disassembly with a focus on “what traffic controls need to be in place” and not “telling [contractors] how to do their work.”
Omega Morgan received various permits from the city, including those calling for street closures, for dismantling of the crane Saturday and Sunday, according to city records. In a construction management plan filed with the city in January 2017, GLY wrote that dismantling was scheduled for January, May and June 2018.
Asked why the crane was being dismantled almost a year later, Ted Herb, president of GLY construction, said in a statement, “The project was proceeding on schedule based upon the current approved contract with the owner.”
Investigators will likely be trying to determine how closely construction crews had been following the manufacturer’s instructions for disassembling the crane, two safety experts said.
“Every manufacturer has its own procedures and it’s a very step-by-step — you don’t jump from one step to the third step — process,” said James Pritchett, CEO of Alabama-based Crane Experts International and a 35-year veteran of the industry. “You have to follow the manufacturer’s procedures.”
Pritchett said investigators would be working to secure the crane and its computer, interview workers and witnesses, photograph and document the scene and analyze inspection records and weather data.
The National Weather Service said wind gusts reached 23 mph in the Lake Union area around the time of the crane collapse.
“There’s no evidence of a microburst,” said National Weather Service meteorologist Chris Burke. “There’s evidence of a small craft advisory-type wind, which is a type of wind we get about 50 times a year.”
Crews had removed the crane’s jib and counter-jib — which make up a crane’s horizontal arm — as well as the tower top, the A-frame-shaped piece that sits atop the vertical mast.
Dave Ritchie, a Texas-based crane safety consultant and frequent expert witness with 48 years of experience, said that disassembling a tower crane is generally a two-day job: the horizontal arm is removed on day one and the vertical mast is removed on day two.
A crane’s vertical mast is composed of 20-foot sections that are generally removed by another crane, two at a time because a tractor-trailer can carry a 40-foot load.
“It’s just a matter of unbolting the tower sections and lifting them down,” Ritchie said. “Some people like to remove the bolts ahead of time.”
The sections are bolted together, usually with two or four bolts or pins at each of four corners. Sometimes, Ritchie said, crews will remove most of the bolts from multiple sections at the same time, leaving only two bolts, at diagonal corners, connecting each section.
While state regulators and industry experts said it was too soon to speculate about what caused Saturday’s crane collapse, bolt removal was an issue at a similar 2012 incident near Dallas, cited by two separate crane experts.
That tower crane collapse, which killed two workers at the University of Texas at Dallas, also occurred during dismantling and featured just the crane’s mast, not its horizontal arm.
“Prior to dismantling of the mast the employer removed mast bolts from every other tower section,” an investigation by the federal Occupational Safety and Health Administration (OSHA) found. “Some of the remaining bolts were also de-torqued.”
A 36 mph gust of wind then caused the mast to “hinge” until its center of gravity shifted “beyond its tipping point, causing the upper eleven sections of the mast to fall and collapse.”
OSHA eventually cited the contractor with six serious safety violations, including failure to “ensure that procedures for disassembling the tower crane prevented the collapse of any part of the equipment” and failure to “adequately support and stabilize all parts of the equipment.”
Terry McGettigan, a Seattle-based tower crane specialist who has long analyzed and catalogued the industry’s accidents, previously laid the blame in the Dallas incident squarely on the early bolt removal.
“Many companies, little by little, over the years, have strayed from manufacturer’s instructions and regulatory rules,” McGettigan wrote in 2012, about the Dallas incident. “In this case, the catalyst was the premature loosening and removal of mast bolts, the wind was only a contributing factor. The mast would have never blown over if all mast bolts stayed torqued to specifications, and not removed until conditions permitted and the assist crane is attached.”
Pritchett said that crews can sometimes develop their own techniques for dismantling cranes.
“But therein lies the crux of the issue, the problem,” he said. “You shouldn’t have your own techniques, you should do it in accordance with the manufacturer’s specifications. People should not have their own techniques.”
This story has been updated to correct inaccurate information provided by the Seattle Department of Transportation regarding which streets were closed during the crane disassembly.