Shelter from the Storm

Schools may be viewed as a safe haven from the outside world, but this is not the case when a tornado strikes. Just last month, a twister struck the University of Maryland in College Park, killing two sisters and leaving $15 million in damage.

School administrators might think that these storms happen so rarely that they are not a serious threat and that school facilities provide adequate protection. But the reality is that students, teachers, administrators and staff may not be as safe as they think.

After schools in Kansas and Oklahoma sustained extensive damage from tornadoes in 1999, the Federal Emergency Management Agency (FEMA) published new, more stringent guidelines (FEMA 361) for tornado shelters in public buildings. Under the new guidelines, existing storm shelter areas may not provide the desired level of safety.

Where is it safe?

In primary and secondary schools, tornado drills typically teach students to go to a makeshift storm shelter, interior corridors, storage rooms, restrooms or other interior rooms. The students are told to sit on the floor and place their heads between their knees.

But are these designated areas really safe? At one elementary school, the designated storm shelter area was stronger than a typical non-reinforced concrete block wall corridor. The roof structure consisted of steel bar joists and metal roof deck; the masonry walls received additional support from a light steel frame — and the corridor was still destroyed by the storm. One wall collapsed, and the other was severely damaged. The roof was gone, and debris was everywhere, most notably in the center of the corridor where children typically would have been sent during a storm.

Tornadoes cause many kinds of stress on buildings and produce differing hazards. Strong winds can collapse walls. The same winds passing over horizontal surfaces can remove roofs and other building components, move heavy equipment, and tumble and roll parked vehicles. Changing wind pressures can exert forces to suck a door into a building or pull it open. Building materials can become airborne debris (missiles). Propelled at high speeds, the debris can penetrate doors, windows and even non-reinforced block walls. Flying glass also can be a problem.