But the one union that does have a contract, covering the 650-member Metropolitan Transportation Authority Police Department, got it, including retroactive raises, thanks to a vote of the MTA board on Wednesday — a development that did not go unnoticed by leaders of other unions. MTA officials have said the new contract for its police force provides three years of raises without increasing expenses because of savings created through union concessions, like having new recruits devote 2% of base pay to cover healthcare premiums; but the officials have declined to provide a cost analysis of the concessions that would show how much savings will be produced.