(a) Account created. – There is hereby created in the State Treasury a Special Revenue Revolving Fund account known as the "County Road Improvement Account” which is an interest-bearing account that shall be invested in the manner described in section nine-c, article six, chapter twelve of this code, with the interest income a proper credit to the account.
(b) County subaccount. – A separate and segregated subaccount within the account shall be established for each county that imposes a county transportation sales and use tax pursuant to this article.
(c) Additional funds. – In addition to the county transportation sales and use taxes levied and collected as provided in this article, funds paid into the account for the credit of any subaccount may also be derived from the following sources:
(1) All interest or return on the investment accruing to the subaccount;