The federal Occupational Safety and Health Administration announced yesterday that it is opening an investigation into the deaths of six workers at an Amazon warehouse in Illinois that was struck by a massive tornado, one of more than 40 that ripped through the region over the weekend.

Nearly half of the 1.1 million-square-foot building was demolished as winds as high as 150 mph (240 kph) tore through the structure. “The west-facing walls of the warehouse collapsed inward, which was followed by multiple structural failures as the tornado moved through the complex,” the National Weather Service said.

The first warnings came relatively early, at 8:06 pm and again at 8:16 pm, when the NWS issued tornado warnings. A “warning” means that a twister has been sighted or radar data suggests one will form. The NWS says that the tornado formed at 8:28 pm as an EF-0, the lowest on the scale, and quickly intensified to an EF-3 as it moved across Interstate 255. More than 20 minutes elapsed between the first warning and touchdown, over double the average lead time.

Amazon told CNBC that warehouse managers directed workers to find shelter at 8:16 pm, which coincides with the second tornado warning. Most workers huddled in bathrooms on the north end of the building, but a smaller group took shelter on the south end, which was demolished by the tornado. Six workers were killed while 39 survived, according to Amazon.

“We’re deeply saddened by the news that members of our Amazon family passed away as a result of the storm in Edwardsville,” the spokesperson told Ars. “Our thoughts and prayers are with the victims, their loved ones, and everyone impacted by the tornado.”

Workplace safety

The deaths have sparked fresh scrutiny of Amazon’s labor practices. OSHA hasn’t revealed the details of its investigation, though it did say that the agency looks into all workplace deaths, and Amazon says it is supporting the agency. Workers at the Edwardsville facility and others in the Midwest have said that their sites have never run tornado drills, and family members have criticized the company for not letting workers find shelter sooner.

OSHA guidelines say that workplaces should “practice shelter-in-place plans on a regular basis” to prepare for tornadoes. An Amazon spokesperson told Ars that the company provides “emergency response training” to new employees and “that training is reinforced throughout the year.”

According to The Intercept, Amazon’s corporate offices were busy troubleshooting network outages and only learned about the tornado strike through media reports. “What the correspondence showed was that initially, nobody knew what was happening,” an Amazon employee told the site. “More and more people joined in on the tickets to troubleshoot the issues only to find out from the media that the building was hit by a tornado.”

No safe room

The Amazon warehouse was built using a “tilt up” technique, in which steel-reinforced concrete walls are poured horizontally on-site and tilted up into place. The roof is then tied into the top of the wall, helping to brace the walls. The structures are cheap to build and favored by warehouses and big-box retailers, but they’re not known for their integrity in storms. Once the roof comes off, the heavy walls become much less stable. On Friday, the tornado destroyed everything in its path, ripping off the roof and pushing down the 40-foot-high concrete walls.

“Tilt-up buildings were not invented for resisting tornadoes,” Grace Yan, a professor of structural engineering at Missouri University of Science & Technology, told the St. Louis Post-Dispatch.

Inside, there were no safe rooms built to withstand the force of tornadoes. In the Midwest, many buildings have basements that double as tornado shelters, but Illinois Gov. J.B. Pritzker said that the Amazon warehouse did not because the area is prone to flooding. In buildings without basements or reinforced safe rooms, it’s common for bathrooms to be the best option during a tornado warning since they tend to be interior rooms without windows.

Amazon spokeswoman Kelly Nantel said at a news conference that the warehouse was “constructed consistent with code” and that the workers had “minutes” to reach shelter in the massive building, which measures approximately 1,000 feet long by 570 feet wide.

https://arstechnica.com/?p=1820579