Q:

The second “that” could be removed from the clause?

there:
I have a sentence. I'd like to know the second "that" could be removed?  
The accident resulted from an outside sudden cause that the driver had no control and (that) occured without any warning signals, thus the accident was inevitable. 
This sentence comes from two separate sentences. The first is: The accident resulted from an outside sudden cause that the driver had no control. The second is: The cause occurred without any warning signals. 
I combined the two sentences together, but I am not sure whether the second "that" should be removed or not? I am often confused by this problem; anybody can give me a general rule?
Thanks! 

A:

If the two sentances are to be combined in that that way, i think the secon "that" is needed. However both original sentence had some other problems:

The accident resulted from an outside sudden cause that the driver had no control. 

should be

The accident resulted from an outside sudden cause that the driver had no control over. (or perhaps "no control of", but "over" is better and more common.) 
The cause occurred without any warning signals. 

This seems awkward to me, although it might be less so if a specific cause were stated. I would favor a variant such as:

The accident occurred without any warning signals.  
There were no warning signals before the accident occurred.
The cause was not associated with any warning signals.

For an overall version:

The accident resulted from an outside sudden cause that the driver had no control over and that arose with no warning signals, thus the accident was unavoidable. 

("Inevitable" would mean the accident was destined no matter what, "unavoidable" means that the driver had no way to avoid it.)

