There are many failsafes built into the massive software application that runs Test Track. They are sophisticated enough to measure the distance between two cars by less than an inch. They are also extremely sensitive, and if it detects one car slightly to close to another, it immediately slows all cars down, aka, the slow stop you may experience. Now keep in mind, these are real working vehicles with engines, and they do break down. If a serious error is detected, especially on the speed test, the cars will come to a stop instantly, or an e-stop. To put it simply, this stop is so fast the smoke keeps moving forward and the vehicle is behind it. The cars literally go from full speed to complete stop in less than 6 inches. However, it is very rare that this happens while in guest operation. Kindof like the springs at the bottom of the Tower of Terror shafts...rarely used, but there in a worse case scenario.
Now, someone else mentioned being afraid of the barrier test. There is actually a failsafe for that as well, and thats one of the things that will stop the ride. If the car gets too close and the doors still haven't opened, the vehicle will stop.
Very very sophisticated program...almost too sophisticated.
Keep in mind as well that the CMs have to keep the load/unload going to prevent a backup. If a guest is slow to get out, etc, cars back up, and the cars slow down.
