I hope I didn't already write about this. If I did, sorry, bad memory!

In research I run across interesting stuff, and this amazed me, especially since I'd never heard it before that. I was reminded of it again.

To get to the south hills of Pittsburgh, I always drive through the Liberty Tunnel, which is a big one, over a mile long. I think it's about 1.10 miles or maybe more. It was built in 1924. It's a major traffic carrier from the city, always crowded.

But the planners didn't finish it before opening it to cars, and one day that brought a catastrophe which could have been avoided. The thing they planned but didn't bother to finish building was the ventilation system.

There'd been a labor strike in the city, of transportation workers. This caused terrific traffic problems everywhere. It was May 10, 1924. Cars were brought to a halt all along the streets leading up to and into the Tunnel. They were stuck in place so long the tunnel began filling up with carbon monoxide.

People must have been bothered by the exhaust fumes, but tried to stick it out, since they couldn't move their cars. Eventually, some people began passing out in their cars. When that started, people abandoned their cars en masse and ran to get out.

The tunnel's length would have made this a horrible challenge. I can't imagine trying to run half a mile while holding my breath. One person was found on the floor of a car, unable to breathe, but the driver had run away, leaving him.

Outsiders who came to the rescue had an even harder problem -- how to go in and come back out without succumbing, a double distance without oxygen. The nearest responding police didn't have gas masks or anything, and really did a courageous job of rescuing people, and suffered the effects of the gas. Another man who lived nearby down along the river's edge came up and went in again and again -- they discovered he'd pulled quite a few people out -- and then was found collapsed outside, and they thought at first he'd been one of the victims in a car, but later discovered he was just a good samaritan.

No one seems to have died, according to the newspaper reports. But lots were hospitalized. This is almost too lucky.

Now there is a dedicated power plant on top of the hill above the tunnel, which handles nothing but tunnel ventilation and other utilities.