You are talking about extension springs? In my experiance torsion springs break very harmlessly. They just snap and unwind but stay on the shaft. Torsion springs are the only kind I have myself seen used for garage doors.
Extensions springs are the old way. Common for a few decades at least. Torsion springs are the new way. They're safer, and smaller, and require less maintenance.
Unfortunately, they're also a bit more fragile. Speculation (mine) is that the metallurgy required to make a big torsion spring makes the material more brittle than standard spring steel. Or maybe they're just thinner and cheaper.
Single piece doors aren't legal in many states, but interestingly it's not because of the safety issues (which are much greater than tracked folding doors with extension springs, due to the angle of extension).
I was interested by this but couldn't find anything about single piece doors being illegal. Being from California I've lived in a few places where these types of doors are common.
No, you had something entirely different so don't try to trivialize something you don't know anything about. Ours fired through the ceiling of the garage and gouged the underside of the roof sheeting because of how the door and springs was engineered. It went off like a slingshot and sent metal fragments upwards at high velocity. Also, they looked like they were from the early 1970's and the springs separated completely as a result of metal fatigue into 3 segments plus some other bits of shrapnel here and there.
Unfortunately, they're also a bit more fragile. Speculation (mine) is that the metallurgy required to make a big torsion spring makes the material more brittle than standard spring steel. Or maybe they're just thinner and cheaper.
They sure are loud when they snap though.