In the 1960s, the NYCTA started a project to lengthen station platforms on its lines in Southern Brooklyn to to accommodate 10-car trains. On July 14, 1967, the NYCTA awarded a contract to conduct test borings at eleven stations on the Fourth Avenue Line, including Prospect Avenue, to the W. M. Walsh Corporation for $6,585 () in preparation of the construction of platform extensions. The NYCTA issued an invitation for bids on the project to extend the platforms at stations along the Fourth Avenue Line between Pacific Street and 36th Street, including those at Prospect Avenue, on March 28, 1969. Funding for the renovation projects came out of the NYCTA's 1969–1970 Capital Budget, costing $8,177,890 () in total.