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There’s obviously something unusual about a person willing to spend a decade figuring out how to prevent roofs collapsing in longwall coal mines.

“Why I find it so fascinating is a mystery to everyone I’ve ever met,” said Chris.

“But I do.”

Most people capable of solving such a time-intensive technical problem would grow bored of it before they were done.

“You have to be smart but not too smart to put in the years,” as he put it.

The federal government has long been a natural home for such characters:

people with their noses buried in some particular problem from which they feel no need to look up.

But once Chris had solved his particular technical problem, he had nothing to do but to look up.

“I said, ‘Okay, I solved the pillar problem for longwall mines.

What do I want to do next?

I want to look at whatever has the direst safety implications.’”

He never questioned the path he had put himself on,
but he soon had new thoughts about how to move along it.

“As far as I was concerned, there was only one reason I was there:
worker safety,” he said.

“At the Bureau of Mines you didn’t have to feel that way.

The kinds of things we did research on were usually not the same things that killed people.

It was more about keeping the mine stable and working.

But I started asking: What’s killing people?”

And so he brought his statistical mind to another mother lode of data:
casualty reports,
which had been meticulously collected since they were mandated by law in 1952.

He began to read individual accident reports.

Patterns leaped out from them.

Chris had always imagined that accidents in a coal mine followed the same logic as casualties on a battlefield.

In war, the rule of thumb had always been that for every soldier who died, three or four would be wounded.

He now saw that for every miner who was killed by a falling roof, 100 were injured.

More oddly, the injuries were occurring in mines where the pillars held up.

“When I looked at the data, the support system seemed to be working, but you had all these injuries,” said Chris.

He assembled another database.

It showed that injuries were being caused by smaller pieces of rock falling between the pillars.

As these fragments could be the size of Volkswagen buses,
they occasionally killed,
but mostly they just maimed. “

I realized that death and injuries were two separate problems,” he said.

“On a battlefield the same bullet can kill or wound you.

Here there are two different mechanisms.”

He’d been so focused on the bullets that killed that he hadn’t noticed the bullets that usually just wounded.

This was the problem that roof bolts had been invented to fix.

Right through World War II, miners had used timbers to support the roof directly over their heads.

In the 1940s, a handful of coal companies showed that it was far more effective to bolt the roof,
effectively to itself.

It struck many miners, at first, as completely weird.

They’d drill a hole into the mine roof and then drive a metal bolt between three and six feet long into it.

The bolt pinned the sedimentary layers together the way a toothpick pins a turkey club sandwich.

The success of the bolt
— and the toothpick
— turns on the presence of at least one solid, strong layer.

Roof bolts, in effect, used strong rock to hold weaker rock in place.

“The single most important technological development in the field of ground control in the entire history of mining,” Chris called them.

Roof bolts were adopted more rapidly than any other technology in coal mining.

Someone had the idea, and almost instantly they were being drilled into mine roofs.

They obviously worked and yet … they hadn’t.

At least not for a very long time.

In the accident statistics, Chris stumbled upon a riddle:

The powerful new technology hadn’t reduced deaths and injuries.

“The accepted story was someone invented roof bolts and it was safer right away,” he said.

“I looked into it and saw it just wasn’t true.

By the end of the 1950s, death rates had actually gone up!”

It was a full two decades before roof fall fatality rates began to decline, and dramatically.

That year, 1969, also happened to be the year that the Bureau of Mines was finally given the enforcement power it needed to properly regulate the industry.