Disadvantaged Business Enterprise Supportive Services Expansion Act The bill increases funding for and expands the disadvantaged business enterprise supportive services program of the Department of Transportation (DOT). The program provides training, assistance, and services to minority-owned small businesses to help them achieve proficiency to compete, on an equal basis, for federal aid highway project contracts and subcontracts. Specifically, the bill (1) increases the annual funding cap for the program from $10 million to $25 million, and (2) authorizes DOT to implement the program at the Federal Transit Administration and Federal Aviation Administration so that small businesses owned and controlled by socially and economically disadvantaged individuals may achieve proficiency to compete for contracts and subcontracts regarding public transportation and airport projects.