It is completely normal and SAFE for a roller coaster train to stop at the top of the hill. Millions of dollars are spent designing roller coasters to do exactly what the Titan did, as well as just about every other coaster in the world. There is nothing at all to fear when you see a coaster train stopped at the top of the hill.

I have described in detail how a roller coaster block system works here, http://www.coasterquest.com/blocksys.htm

A coaster can stop at the top of the hill for a few simple reasons:

LOSS OF POWER
BLOCK SYSTEM HALT
SWITCH FAILURE

LOSS OF POWER

At some point, many parks experience the same inconvenient power outages as the rest of us. If a coaster loses power, it can stop on the hill or in a brake. It WILL NOT stop on the track or in a loop if it loses power. Gravity is the sole propulsion of a roller coaster once it has left the top of the hill, so there is no way for it to stop it until it reaches a brake. Passengers are always removed from the trains during a power failure. The option is not available to remain seated and resume the ride when power is restored.

BLOCK SYSTEM HALT

The block system will occasionally sense that the trains are too close, and stop the train in the preceding unoccupied block. It just so happens that the sensors for the "Lift Hill" block are located at the top of the hill, and so that is why it stops there as opposed to the middle or the bottom of the hill.  The sensors are always located at the outboard end of the block like this because not only does it provide a location for the train to be stopped, but the sensors also shows the location of that train and makes sure that the train in the station can not be dispatched until the train on the hill has cleared the final sensor at the top of the hill. When a train stops on the lift because of a block system halt, generally the maintenance personnel will want to simply clear the occupied block and then send the train which sits on the hill. However, a park employee will always walk to the top of the hill to discuss the issue with the riders, and if a person has a medical issue, or is traumatized by the situation and wished to be taken out of the train and walk down the hill, then the park is obligated to do so. In this case, it is easier to simply evacuate the whole train then take one person down and risk having someone else change their mind and wish to be removed as the maintenance person is preparing to send the train.

SWITCH FAILURE

Switch/ sensor failure can sometimes create a "phantom train" and will cause the computer to see a train which is not really there.   This then causes the block system to once again kick in and shut down the ride. In this event, the trains could stop in any given block, including the hill block. This is not a 5 minute repair, and will require a few test runs in order to re-open, so for this reason, the riders in the train will be cleared from the train at the top of the hill.   Once the proximity switch or sensor is replaced, the train can then be returned to the ground, tested and re-opened.

Hopefully with this insider information on how roller coasters work, you will feel safer and more reassured when you see a coaster train safely stopped at the top of the hill. If it happens to you, sit back, enjoy the view and be glad that you are getting to experience some quiet time on top of a roller coaster that few people are so fortunate to be able to experience. Thanks for visiting CoasterQuest, and have a safe summer!  --Walt Reiss