How safe are roller coasters?

Believe it or not, some of the world’s most forward-looking
engineering is actually in operation right now, in the
unexpected setting of the world’s theme parks.
From the pioneering 18th Century ‘Russian Mountains’, people have
been hooked on the frightful thrill of a roller coaster – and ever since,
the challenge has been to make an even bigger, even better, even more
terrifying one.
Today, they incorporate solutions that are at the leading edge of
scientific development. This means they are able to accelerate as fast
as a drag racer and let passengers experience G-forces way in excess of
a Formula 1 race car.
They do all this in complete safety, having passed the very
strictest engineering standards. People travel for miles to ride on the
latest roller coaster – they’ll even cross continents just to experience
the thrill.
Roller coaster trains are unpowered. They rely on an initial
application of acceleration force, then combine stored potential energy
and gravitational forces to continue along the track. This is why they
rise and fall as they twist and turn.
There are various methods of launching a roller coaster.
Traditionally, a lift hill is used – the train is pulled up a steep section of
track. It is released at the top, where gravity transfers potential energy
into kinetic energy, accelerating the train. Launches can be via a chain
lift that locks onto the underneath of the train, or a motorised drive tyre system, or a simple cable lift. There is also the catapult
launch lift: the train is accelerated very fast by an engine or a
dropped weight.
Newer roller coasters use motors for launching. These generate
intense acceleration on a flat section of track. Linear induction motors
use electromagnetic force to pull the train along the track. They are
very controllable with modern electronics. Some rides now have
induction motors at points along the track, negating the need to store
all the energy at the lift hill – giving designers more opportunities to
create new sensations. Hydraulic launch systems are also starting to
become more popular.
Careful calculation means a roller coaster releases roughly enough
energy to complete the course. At the end, a brake run halts the train –
this compensates for different velocities caused by varying forces due
to changing passenger loads.