That’s right, roller coasters generally get faster throughout the day.
Your experience of the same roller coaster could, and most likely will,
be slightly different each time you ride it. This seems a little counter-intuitive.
Theme parks often market their rides using speed, stating their new roller coaster reaches exactly
80kmh 50mph for example; and, though the physics of the earth doesn’t change from ride to ride,
there are a huge number of other minor factors that can affect how the train will
perform through the circuit. So, why do roller coasters generally speed up throughout the day?
Though the list of factors is long, one of the most important is temperature. Temperature has
a direct impact on how fast roller coasters are able to run. To ensure the trains of the ride
make it through the course, theme parks apply grease or lubricant to the wheels. This aims to
reduce friction and wear between the wheel and the train’s axle. The thicker the lubricant,
the higher the coefficient of friction, and the quicker the wheel slows down. Temperature
changes the viscosity, the thickness, of the grease. The warmer the lubricant,
the lower its viscosity, and therefore the lower its coefficient of friction. This means that the
wheels can rotate more freely, therefore allowing the train to run faster. Interestingly, it's the
temperature of the lubricant over time which has such a drastic effect on the speed of a ride.
At the beginning of the day, when a roller coaster first opens to guests, the trains are cold and
the lubricant has been freshly applied. This means its viscosity and coefficient of friction is high.
As the train completes more laps around the roller coaster’s circuit, the lubricant
begins to warm up. Over time, the grease becomes hotter, and its viscosity decreases.
This, in turn, reduces the coefficient of friction, allowing the trains to run faster.
Because of this, the length of the time the theme park is open will also affect how fast a
roller coaster runs. A longer day means that the trains complete more circuits around the track,
resulting in warmer lubricant, less friction, and faster speeds. As a result, some roller
coasters are known to give fantastic rides at night time, as the ride has been operating all
day long. The temperature of the day can also help to enhance this effect. Temperatures are
often lowest in the morning, resulting in slower rides. By the afternoon, temperatures
often spike. An extremely warm sunny day could see roller coasters running excessively faster.
The difference between a cold ride, and one which has warmed up, can sometimes be drastic.
Because the trains maintain their speed throughout the circuit better, the forces experienced during
the ride by guests are often increased. This means that parts of the roller coaster may feel more
intense, fast paced, and rapid later in the day. Often, roller coaster enthusiasts are cautious to
make a judgement about a specific roller coaster until later in the day when it has properly warmed
up. But they’re right to do so! We measured this effect on Flug der Dämonen, one of the flagship
roller coasters at Heide Park in Germany. By measuring the g-force experienced on the ride over
time, we were able to pinpoint the exact start and end points of the layout. Shortly after opening,
the ride experience was measured to last 42.6 seconds. Roughly 5 hours later, that time had
reduced to 40.5 seconds. Over multiple hours, Flug der Dämonen had gotten 2.1 seconds faster,
a noticeable 5% decrease in the time it takes for riders to navigate the course!
Though temperature plays a big part in causing roller coasters to run faster over the course of a
single day, other factors can affect the speed and duration of a ride too. In fact, those on board
the train with you might determine how fast you travel through the circuit. The heavier a train
is, the more momentum it has, and the longer it takes to slow down. This means that a fully loaded
vehicle, full of excited passengers, will complete the layout faster than one with only a few riders.
This effect will have more of an impact on some roller coasters compared to others. For example,
adding passengers to a small train could double its overall weight; whereas a longer train might
only see a 20% increase. As a result, a fully loaded train will have more of an
impact on lighter and shorter vehicles compared to heavier, longer ones. Again, a lighter train
will have less momentum and will therefore be more susceptible to forces, such as wind resistance.
As we’ve already seen with temperature, weather can alter the speed of a roller coaster. Depending
on its direction and speed, wind can have a huge impact on how fast a ride completes the circuit.
High wind speeds facing opposite to the direction of the train will push against riders,
slowing them down. Though, the opposite can also be said, as a gust in the right direction
might help to push the train along the track. In any case, many roller coasters have a maximum wind
speed in which they can operate. This is done to reduce the risk of the ride slowing down too much
and not making it around the entire course. Rain can also impact the speed of the trains too
by serving as an additional lubricant. If the track becomes wet, the friction between the
track and wheels is reduced. This allows riders to maintain their speed better throughout the course.
Finally, lightning arguably has the largest impact on a roller coaster's speed. If lightning is in
the area, a roller coaster will cease operation, reducing its top speed to a whopping 0 kmh.
Most of the factors discussed so far can’t be precisely controlled, especially the weather
conditions on the day. Theme parks do however have a few tricks they can employ to make their
rides faster. One of these is the type of wheel a roller coaster train uses. Steel
roller coasters commonly use plastic wheels; two of the most common include nylon and polyurethane.
Nylon is the harder material of the two, while polyurethane is softer. Harder materials have
a lower coefficient of friction, meaning roller coaster trains with nylon wheels will run faster
than those with polyurethane. Although, as the temperature of the wheel increases the material
becomes softer, increasing the coefficient of friction, helping to slow the trains down.
Some theme parks also use the variety of wheel materials to help control the speed of the train.
For example, The Big One, Blackpool Pleasure Beach’s tallest roller coaster,
uses different wheels depending on the weather. In summer, when it’s hotter, the trains usually
use a softer wheel to reduce their speed. Whilst in the colder seasons, the park uses
harder wheels to ensure the train maintains its speed at lower temperatures. Other parks
might utilise a combination of harder and softer wheels to achieve the right speed too. Wooden
roller coasters on the other hand often use steel wheels, which have an extremely low coefficient
of friction against the steel running rail of the wooden track. As a result, wooden roller
coasters often maintain their speed throughout the ride better than their steel counterparts.
Finally, as stupid as this sounds, paint can also affect the speed of a roller coaster train.
Thick layers of paint on the ride’s track can increase the friction with the train’s wheels,
slowing it down. Over time the train begins to wear down the paint, causing a line to appear on
the track with no paint present. Though some amusement manufacturers have gone further,
giving theme parks the option to have these worn lines on the track from the start.
With a multitude of variables affecting the speed of a ride, could a roller coaster go too fast? The
short answer is no. Roller coaster manufacturers take these conditions into account during the
design phase to ensure rides operate safely at a range of speeds. If a train was to run too
quickly, it could subject riders to uncomfortable forces, or begin to degrade the components of
the roller coaster faster than intended. Some rides have been known to overshoot the brake
run slightly, causing the safety systems in place to temporarily stop operation of the attraction.
As a result, roller coaster manufacturers have come up with a range of methods to ensure this
doesn’t happen. The most common is trim brakes, small brakes placed at specific points along the
track to help moderate the speed of the train. Unlike brakes at the end of the ride, which
activate by default to bring guests to a stop, trim brakes aren’t always in use. Instead they’re
adjustable. This means that the roller coaster’s computer system is able to alter how much braking
force is applied to the train. By doing this, the speed of the train can be reduced just enough to
ensure it’s travelling at the appropriate speed. Many rides also constantly measure the time it
takes each train to navigate the course. It’s manufacturer will have determined a minimum and
maximum time in which the ride can operate safely. If the train is travelling too fast for example,
it might complete the course quicker than this minimum time. An alert would then be sent to the
ride operators to notify them trains are running too quickly, or it may shut down altogether as a
precautionary measure. The same would also occur if the ride was running too slowly.
And yes, roller coasters can run slower than designed too. As mentioned earlier, if a train
is travelling around the track too slowly it might not complete the entire course. A big gust of wind
could cause it to valley, resulting in the train not making it over the next hill. This is often
most likely to occur at the start of the day, where temperatures are lowest, the lubricant is
cold, and the trains are empty. Fortunately, theme parks have methods to prevent this from happening.
Before guests board, all theme parks cycle the trains a few times to ensure the ride is safe
to operate. Whilst doing this, they’ll sometimes fill the trains with water dummies or sandbags,
to mimic the weight of riders. This gives the trains more momentum, helping them to maintain
their speed throughout the circuit. Once the lubricant has warmed up enough, due to successive
runs, the dummies can be removed. Other parks use heaters within the station to help warm up the
wheels, and maintain their temperature while the train is stationary. Some wooden roller coasters
even feature anti-roll back devices near parts of the ride the trains will often traverse slowly.
These are large metal teeth which the train can move over forwards, but not backwards due to
their design. Therefore, if a train failed to climb the hill, instead of falling backwards,
it would be caught by the anti-rollback device and remain in position. Ride maintenance staff
can then push the train over the hill, allowing it to complete the remainder of the course.
Ultimately, maintaining the speed of a roller coaster is a balancing act.
Many factors can both help and hinder the train’s speed, so parks have to be creative
with their solutions. Some use different types of wheels to help control the speed of the
train in a variety of weather conditions; while others employ trim brakes to ensure
guests aren’t travelling too quickly at various points during the ride. With that being said,
it's simply not possible to make a roller coaster give identical rides every time. Now,
using the knowledge you’ve just learnt, you’ll be able to cheat the system. It’s quite simple;
want a fast ride on your favourite roller coaster? Wait until the end of the day...