Comments about technological history, system fractures, and human resilience from James R. Chiles, the author of Inviting Disaster: Lessons from the Edge of Technology (HarperBusiness 2001; paperback 2002) and The God Machine: From Boomerangs to Black Hawks, the Story of the Helicopter (Random House, 2007, paperback 2008)

Sunday, June 12, 2011

Stadiums and Storms: What's the plan?

Flying into MSP Airport from a meeting in Las Vegas on May 10, I snapped this picture of a big cumulonimbus over the Twin Cities:
It was prime time for storm-shooting because clear skies to the west allowed the late evening sun to beam into the inner reaches. 

When a cloud pileup has a cap like that it's called a cumulonimbus capillatus. I'd estimate the cloud tops at 45,000 feet.

After a half-hour hold, Air Traffic Control cleared us to land. On the glide path to MSP, I could look down to see our new Target Field ballpark, where the Minnesota Twins were in a rain delay, before losing to the Detroit Tigers.

The frustration started two hours before I flew by. Hearing the eerie wail of storm sirens, fans had fretted about a tornado or lightning. But the game went on until hail arrived. As chunks the size of golf balls landed on the grass, the announcer asked people to move to cover. Here's what I've distilled from the event:

Was there a tornado threat to Target Field that night? No. The Twins have an on-site meteorologist at all games, and he determined that no dangerous storms were on track for the ballpark. The sirens are a county-triggered method to alert a wide swath of residents about the possibility of storms. While it sounds spooky, a siren doesn't mean that a tornado is bearing down on the people hearing it. It means they should tune into weather reports and be prepared to find shelter. 

Did the ballpark let people leave, seek their own shelter, and then re-enter with the same ticket when the rain delay lifted? The Twins organization wants fans to seek shelter from storms inside the ballpark rather than sprinting outside to reach other buildings and parking ramps. Standard operating procedures were in effect: any fan wanting to leave and re-enter would have to have their ticket signed by an usher-team leader. That would have been quite a line.

Why did the ballpark management close the bathrooms on the upper concourse? To discourage people from trying to seek shelter in them. The upper bathrooms aren't protected by masses of concrete and steel like the lower levels are. Such a precaution probably seemed heavy-handed to those caught in the pedestrian jam and wanting to use the bathrooms ...

If people on the upper levels were to go down to lower levels, why did the ballpark management turn off the escalators that can take large numbers of people downward? To force more people into the jam on the lower levels with escalators would have risked a pileup.

What were fans supposed to do when the announcer asked them to seek shelter? Move into enclosed areas in the lower levels, including the main concourse. There's also a roomy service level below the concourse, completely ringing the stadium, and reachable by stairwells reserved for emergency use.

Post-storm, the official response was that 40,000 fans should be able to leave their seats and find shelter inside the ballpark within 12 to 15 minutes after the first announcement. 

Hmm. Given what I hear about the pedestrian jam-up that night, more fan-direction is needed. The quarter-hour response sounds like something a computer model came up with, by assuming that fans will move like fluid in a pipe; that they're highly cooperative and thoroughly familiar with storm plans. 

Instead thousands jammed into the main concourse so tightly that even those that knew to head for the service level couldn't make much progress.
But the good news is that -- unlike a lot of older venues -- Target Field was built with storms in mind, so the hardware is in place.

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