Worrying to see trains so close to one another

On several occasions, trains have been forced to stop very close to one another. There are a variety of reasons for this, including the testing of the new signalling system.

I am sure that I am not the only train commuter who finds it unnerving to see two trains so close to one another.

Are the trains dependent purely on the train driver's skills to stop at such close proximity?

What assurance is there that there won't be an error of judgment on the part of the driver, which could have serious consequences?

Is there some technology in place, to prevent two trains from colliding in such a situation?

Ganesh Ram Ragavan