"Waterfall model is a document driven process.
While spiral model does not requires the document."


Is this mentioned anywhere? Because at the end of the last
prototyping in spiral modeling, water fall model process (
like detail design, coding, testing, acceptance) is applied,
and hence it should also be considered as document driven
process. Please comment. 

Yes I agree that spiral modeling will help client to
understand the approximate characteristics of end product
and on the basis of which he can rework on the requirements
and hence it is suitable for big projects with high risk
factor involved.