I was listening to this piece on speed cameras in the outer boroughs of NYC.
It is a great article and both sides come across well. Long story short-
Tickets are issued for 11 mph over. Some official talks about the different stopping distances at speed. One of the set of numbers he throws is something around the lines of, if you are going 40 as opposed to 30- your breaking distances are 100 feet longer. That seemed high to me. Can we find anything to support or disprove Mr. Official? What kind of vehicle are we talking about and with what weight? Should we link to the top gear?