Surface and Maritime Transportation Security Act This bill requires the Transportation Security Administration (TSA) to: (1) assess, and implement a risk-based security strategy to address, the vulnerabilities of and risks to surface transportation and maritime transportation systems; (2) develop a management oversight strategy that identifies the parties responsible for implementing the security strategy; and (3) submit a report that describes a risk-based budget and resource allocation plan for surface transportation sectors that reflects the security strategy. The TSA shall establish the Surface Transportation Security Advisory Committee to make recommendations pertaining to surface transportation security. In addition, the bill: directs the Department of Homeland Security (DHS) to expand the TSA's explosives detection canine team program and to deploy next generation technologies to detect nuclear material, requires the Government Accountability Office to study specified matters related to surface transportation, expands the permissible uses of railroad security improvement grants, requires the TSA to issue a decision on the use of a passenger vetting system by the National Railroad Passenger Corporation (Amtrak), requires the TSA to establish a program to promote surface transportation security through the training of surface transportation operators and frontline employees, expands the transportation security card program to allow individuals subject to credentialing or a background check to apply for a transportation security card, and requires DHS to evaluate cargo-container scanning technologies. The bill authorizes appropriations for FY2018-FY2021 for DHS to award surface transportation preparedness grants, subject to specified certification requirements.