Alexander at A Little Off Main gets to what I've been thinking. If "nobody" is at fault for the train whistles, then it's a failure of the administration. Even if evil genius City Administrator Lori Luther steps forward now and takes the blame (unlikely), it will still reflect on the mayor.
You may try to claim that it's unfair, but so far there have been no consequences at the local level. If nobody is held accountable, the voters have no choice but to hold their elected official accountable. That's the mayor.
I think it's too late to point the finger of blame at anyone else.