Motorsports of any kind is a dangerous game, but the improvements in safety over the decades has been astonishing. It used to be in Formula 1 racing that at least 10% of the drivers were killed every year - and that was as recently as the 1960s. There has not been a driver fatality in Formula 1 since 1994 when both Ayrton Senna and Roland Ratzenberger were killed on the same weekend in different accidents. Two course marshalls have lost their lives in that time, both killed by...... flying tires. Wheels are now tethered (that's the word you were looking for, chevyboyac) in most forms of motorsport but even that isn't a guarantee. When car impacts car, or wall, or whatever, stuff is going to come loose. And the faster the car is going, the faster and farther that stuff is going to fly.

Crowds have moved further away, fences have gotten taller and stronger. But those who work trackside are at the highest risk from flying debris, and it looks like this woman fit that description. The drivers are incredibly well protected, and the spectators are far removed. Track workers, pit personnel, etc are virtually unprotected against heavy, flying debris. You can put a helmet on them and make 'em wear fire suits (which is very common) but throw a tire/wheel combo at them at 100+ mph and nothing much can be done to prevent serious injury or, in this case, death.

But we've come so far from those days when the drivers wore no seatbelts, their helmet was but a leather cap, and even open cars lacked any sort of roll over protection. Heck, most of the time a drivers shoulders were up higher than the surrounding body work, let alone his head! Drivers will continue to die, as will track workers, pit crew, etc. But I doubt we'll ever see (and pray we don't) another incident like LeMans in 1955 that killed one driver and perhaps as many as 100 spectators. That was the event that caused Mercedes to pull out of motorsports for almost 40 years.