The city-wide speed limit in NYC is 25mph, unless marked down to 20mph in special areas. This law needs to be enforced aggressively. Drivers don't need a big fine; I bet people will adjust their behavior from just a stern talking-to and a $20 ticket or something.
As it stands right now, people are needlessly dying for no reason. Driving in the city, all your time is sucked up by sitting at traffic lights. It doesn't matter how fast you get to the next traffic light, because if you're speeding, it's going to be red.
(There was an interesting pilot program to give $50 tickets to people exceeding the speed limit by 30mph in school zones. Tons of opposition. This makes me think what we really need to do is just start closing roads to private vehicles. People think they're entitled to run over children at 50mph, just because they fucking feel like it. Where did we go so wrong!?)
Looking out my window on a small residential street in Brooklyn, I'm always amazed at the traffic snarl. It's basically a dead-end street. And yet someone is always double-parked, preventing fire trucks from going through. One time a fire truck got boxed in by someone double-parked, and an MTA service vehicle that double-parked behind it. Eventually the MTA vehicle got towed away, and the fire truck slowly backed out. Hope it wasn't an important building that was burning down.