Falling down is the second biggest cause of accidental death (after car accidents).
Today’s invention is therefore an airbag which can be located in a pod within a bannister or handrail.
Sensors in the stair treads would determine where the next footfalls should occur…if this pattern were noticeably disrupted suddenly or if there were a sufficiently hard impact on a tread-based sensor, it would automatically fire the airbag inflation mechanism.
The inflation process could be less violent than in a vehicle, so as not to upend other people in transit, but still allow cushioning, slowing and arresting of the victim’s fall.
A fall would trigger other bags lower down the staircase (especially one on the bottom landing).