Streamlined and Improved Methods at Polling Locations and Early (SIMPLE) Voting Act of 2015 Amends the Help America Vote Act of 2002 (HAVA) to require each state to allow individuals to vote in a federal election on each day during the 15-day period ending on the second day immediately preceding the election date in the same manner as voting is allowed on election day. Requires a state to ensure that each polling place that allows early voting in a federal election is located within reasonable walking distance of a stop on a public transportation route. Requires the Election Assistance Commission to issue standards for the administration of early voting in a federal election. Requires each state to provide a sufficient number of voting systems, poll workers, and other election resources (including physical resources) at a polling place used in a federal election to ensure: (1) a fair and equitable waiting time for all voters in the state, and (2) that no individual will be required to wait longer than one hour to cast a ballot at the polling place. Requires each state to develop, and implement to the greatest extent practicable, a contingency plan under which it shall provide any polling place on a federal election day whose waiting times exceed one hour with additional poll workers, machines, ballots, and other equipment and supplies, including a polling place at which individuals may cast ballots before the election date. Requires the Commission to report to Congress biennially on the impact of this Act's early voting and waiting time provisions on the administration of elections for federal office. Prescribes requirements for the counting of provisional ballots that will be treated as votes. Allows civil money penalties, intervention by aggrieved parties, and private actions to address HAVA violations by a state or jurisdiction.