The type of ride most prone to crashes is the roller coaster, though several other types of rides can crash. The most common cause of crashes is the "station brakes failure" breakdown on roller coasters. On roller coasters with multiple trains, this causes a crash when one train is still in the station and another train comes in at full speed. Due to the station brakes failing to slow the train, it collides with the back of the stationary train. On roller coasters with single-car trains, such as Single-Rail Roller Coaster and Wild Mouse variants, this is not as much of a problem.Poorly-designed roller coasters can be subject to crashes, even if the ride is not broken down or if a ride has not experienced a Station Brakes Failure breakdown. Often, these rides will not pass their initial ride testing and will not be opened to the public. However, sometimes a ride mid-design can cause ride crashes under certain circumstances. For example, the roller coaster Dynamite Blaster in Dynamite Dunes has a lengthy ride section after the train leaves the station but prior to it reaching the lift hill. If a train entering onto the lift hill is stopped due to a safety cut-out breakdown, there is a remote possibility that another train that has exited the station may collide with it. This example, like many others, can be prevented by increasing the minimum wait time at the station, or by reducing or eliminating space between the station and lift hill.
Certain roller coasters types can crash in different ways; the Bobsled Roller Coaster, Reverser Roller Coaster, Flying Turns and Wooden Side-Friction Roller Coaster can crash as a result of cresting hills too quickly. As the trains/cars on these roller coasters are not attached to the track, they can fly free when going over hills. Sometimes they may pass tests, but after opening, the added weight of guests will cause it to move faster and may crash. Water Slides can crash in a similar way, though these crashes are preventable by using closed track at the crests of high-speed hills. The Ghost Train and Haunted Mansion Ride will crash if they travel round a curve too fast.
Other rides that may crash include the Whoa Belly/Launched Freefall. The Whoa Belly can only crash when the launch speed is set too high and it leaves the vertical section, crashing when it hits the top of the tower. Roller coasters set to "powered launch mode", such as the Shuttle Loop, can crash similarly, if they fly off the track from a launch that is too fast.
Universally, any tracked ride will crash if two trains collide with each other at a combined speed of 30MPH/48KPH or if they leave the track for any reason.
It is also possible for a Log Flume to crash, especially if a reverser segment is located shortly after a large drop.
Crashes are preventable on most non-roller coaster rides and roller coasters with unattached cars by simply designing them well. Make sure that vehicles don't crest hills too quickly on rides where the vehicles are unattached, and always test rides with powered launches.
In RollerCoaster Tycoon, it is difficult to completely prevent roller coaster crashes. The easiest way to prevent station brake failure crashes is to remove all but one train from the ride, though this reduces the number of guests that can ride the coaster at once, and thus profitability. For coasters with more than one train, implementing brake runs can reduce the speed of the trains midway through the track or right at the end, giving the trains less momentum and possibly preventing a crash. One way to keep the number of breakdowns low is to set the inspection time for roller coasters to "Every 10 minutes", and placing a mechanic right at the exit of each roller coaster with a patrol path on the exit of the ride. This keeps the reliability of the roller coaster high, and in the event of a station brakes failure, a mechanic is right there to quickly react. A different way to prevent crashes is to make sure that there will only ever be one train in or near the station by changing the minimum and maximum wait times. These times can change for each individual roller coaster, and there are no universal safe values or easy formula for safe times; the best way to find out good times is to experiment. These are easier to find out for longer roller coasters. Another option is to design the coaster delicately to be long enough that trains enter the station at a safe speed, eliminating the chances of crashing due to high speeds.
In RollerCoaster Tycoon 2, using block brakes can drastically reduce the possibility of roller coaster crashes to almost nothing. Block brakes operate by completely stopping the train and not letting it move forward until the next section is clear of other trains, preventing even the slightest possibility of two trains colliding. Using many block sections on a long roller coaster can allow many trains to safely operate on the track without building an extremely long station.
Also, if a ride crash is happening, the guests on board do not actually die until the first vehicle is destroyed - helpful for catching derailing crashes in mid-air.
In RollerCoaster Tycoon 3, peeps cannot die under any circumstances, thus, crashes are less of a problem. Crashes can still occur if the train derails due to an incomplete circuit, in which case, the cars do not explode immediately after touching land or scenery; the cars simply explode 10 seconds after derailing. This means that derailed cars can slide across paths, knocking over peeps along the way (see: Peep Bowling). Also unlike the prequels, when two trains collide at high speeds, they simply bump off each other rather than exploding.
After a ride crashes, a number of negative effects occur. The ride that crashed will suffer an extreme loss of popularity, as in the guests' eyes the ride "isn't safe." Nothing will change this reputation except for rebuilding the ride completely. This can be easily done for rides that stay above ground by simply saving the track design, demolishing the old ride, and placing a new one from the saved track design. The best option for rides that go underground is to either make an entirely new design, or rebuild same design piece-by-piece while demolishing the old ride piece-by-piece.
If the same ride is kept, eventually guests will start riding it again, but it will be a slow recovery and the ride will almost never reach the same popularity that it had before. You could also close the ride for months, after a ride crash, then reopen when the reliability is back to a reasonable area. Other effects of ride crashes include a loss of popularity for the park, and a drop in park rating. These losses will quickly recover if the ride is closed, edited, and tested. To reset a crashed ride, doubleclick the red button on the traffic lights/flag, then it can be used again.