即使⋯⋯也 (jíshǐ... yě) means "even if...still...." In this construction, the first clause (after 即使) is a supposition, which is then struck down as impossible by the second clause (after 也) of the statement.
即使 + Hypothetical Statement + 也 + Action
Note that the clause used after 即使 must be hypothetical, otherwise 虽然 should be used.
In the sentence above, it being rush hour is not a hypothetical statement, so it is incorrect to use 即使.