I don't know what it means in civil but here in my office when I interview someone,but could not get right assessment of his capabilities,In that case I offer him interim salary, and thats interim valuation of person.
what are uses?
I case person don't perform to expectation he can be asked to leave with out investing too much.so one can save mony.
for a contract, you use interim valuations to pay the contractor a certain amount of money based on what has been effectively done. this allows the contractor to keep his assets a bit more fluid.