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Weather, Human Error Thought To Be Cause Of Fatal Crane Accident

UPDATE, MAY 1, 6:51 P.M. PT: This story has been updated to reflect new information on the accident and the investigation.

The investigation into Saturday's Mercer Street crane collapse in Seattle that killed four people now includes five companies.

Cranes hover over the skyline in Seattle's South Lake Union, the most crane-dense section of the city.

Seaburg Construction, which employed the operator of the tower crane before workers began to dismantle it, now joins GLY Construction, Northwest Tower Crane Service, Omega Morgan and crane owner Morrow Equipment as the parties being investigated by the Washington State Department of Labor and Industries, according to a report by the Seattle Times

Meanwhile, city officials said the Seattle Department of Transportation relies on the contractors to request street closures when potentially dangerous activity is taking place. In this case, subcontractor Omega Morgan requested a permit to shut down Valley Street and Boren Avenue on Saturday and Sunday, but not Mercer, the Seattle Times reports.

Though the official investigation is months away from completion, speculation around what caused the crane accident now includes a combination of weather and human error, according to CNN. After reviewing video, trial attorney David L. Kwass, who has handled crane accident lawsuits, said it appeared that the pins connecting the crane’s segments may have been removed too soon.

Forecast gusty winds were blowing through the area at the time of the collapse. A meteorology report from Cliff Mass, local weather guru and professor of atmospheric sciences at the University of Washington, show wind gusts reached 35 mph at 3:26 p.m. at a weather station near the site just minutes before the collapse. 

The four people that died in the accident include experienced ironworkers Travis Corbet, a U.S. Marine and resident of Portland, and Marine Corp. Reservist Andrew Yoder of North Bend. Nineteen-year-old Sarah Wong from South Pasadena, California, and 71-year-old city of Seattle employee Alan Justad were killed in separate cars on Mercer Street, according to the Seattle Times

Six cars were hit and three other people, including a 4-month-old infant, were injured and taken to the hospital. Another person was injured but did not go to the hospital.

The incident took place in the South Lake Union neighborhood, one of Seattle’s fastest-growing areas. It is home to several tech companies, including Amazon.

The crane was in the process of being dismantled at the time of the accident.

The campus is being developed by late Microsoft co-founder Paul Allen's Vulcan Real Estate. Vulcan is responsible for much of the development in the area. The general contractor is Bellevue-based GLY, which is also the general contractor on Amazon Block 21, Seattle Cancer Care Alliance, Overlake Medical Center and Two Union Square, as well as several other projects. 

The Google campus, set to be complete this quarter, sits on Mercer between the streets of Fairview and Boren, overlooking South Lake Union. According to reports, the crane fell off the building that was closer to Fairview.

The accident closed down Mercer Street, one of the busiest streets in the city, in both directions while the investigation is underway. Street repairs will need to be complete before the street reopens to traffic. Severe traffic congestion is expected.

Google will occupy the office space in the four-building, 607K SF project, which also includes 150 apartments, according to the Seattle Times. Google agreed to lease the space for 14 to 16 years, GeekWire reports.  

For three years in a row, Seattle has had the most cranes in the country, a sign of the construction boom in the city, according to KOMO News. As of January, the number sat at 59. The region had another deadly crane accident in 2006 when a crane fell off a building in Bellevue, killing a man who was sitting in his apartment.

A similar crane incident was reported at The University of Texas at Dallas in 2012. A construction crane was being dismantled when it fell across a building, killing two workers.

Between 2011 and 2015, 44 people are killed every year in crane accidents, according to the Bureau of Labor Statistics

A report on the cause of crane accidents worldwide cites the erection and dismantling of cranes to be the number top cause of crane accidents, with severe weather coming in second. Both situations were simultaneously occurring at the moment that the crane crashed onto Mercer Street, which has a daily traffic volume of 60,000 vehicles.