(a) General rule.--If the need arises for transfers to counties because of emergency or equipment needs, the department shall draw from the allocations of all counties in a manner such that the proportion of the transfer for any given county equals the proportion of the total allocation for that county to the total highway maintenance appropriations and executive authorizations.

(b) Effect on subsequent allocation.--Expenditures from transfers made to or from any county for emergency or equipment needs shall not become a part of the computation for such county for the subsequent years' maintenance allocation.