News   Transit Agencies Face the New Calculus of Broader Backsides By CHRISTINE HAUGHNEY Each time a New York area transit agency decides to purchase new trains or buses, it must consider whether to make its seats wider, usually at the expense of passenger capacity. Graphic: A Bit More Room   Suit on Police Treatment of Livery Riders Is to Proceed By AL BAKER A civil rights lawsuit accusing the New York Police Department of flouting the rights of livery cab passengers has been allowed to move forward by a federal judge.   Tense Relations With Officers in a Crime-Ridden Precinct By LIZ ROBBINS In East New York, Brooklyn, the wariness between the police and residents has been a topic of conversation, especially since a shooting on Thursday night.