D.C. Code § 9-317: Van Buren Street Subway.

No street railway company shall use the subway and approaches to carry Van Buren Street under the tracks and right-of-way of the Metropolitan branch of the Baltimore and Ohio Railroad Company for its tracks until said Company shall have paid to the Collector of Taxes of the District of Columbia a sum equal to one-fourth of the total cost of said subway and approaches, to be applied to the credit of the District of Columbia.