Collision on Disneyland's California Screamin' coaster

Yesterday, there was a low-speed collision on the California Screamin' roller-coaster at Disneyland's California Adventure park, hospitalizing 15 of the 48 riders. From The Disney Blog:
The Purple train ran into the back of the red train that sits to the right of the image. They are in a braking zone. The railing on the right of the track is an emergency unloading zone if a train has to stop in a braking area. From what I can tell this is the next to last braking zone before the train enters the station. Trains entering this braking zone would not generally come to a full stop. But they would if there was a train ahead of them waiting to enter the station.