New York's speed limits are laid out in the Vehicle and Traffic code, section 1180. New York has a basic speed law, which makes it illegal for drivers to drive faster than is "reasonable and prudent" based on current driving conditions. Other than that, the state sets a maximum speed limit of 55 miles per hour, except for some sections of certain highways where the speed limit is 65 miles per hour. New York speed limits can be set lower than the 55 mph maximum based on engineering and traffic studies and local conditions. Speed limits are usually determined by a traffic and engineering study to measure the speed that people naturally drive the stretch of road in question. The speed limit is then set to be close to the 85th percentile, the speed that 85% of drivers feel comfortable driving at. New York speed limits can be reduced even further than recommended by traffic studies near special hazards such as construction work and schools.
Whether you are part of that 85% of people who are comfortable going the speed limit or not, you must obey the posted speed limit or you risk getting a ticket. If special hazards such as rain, snow, ice or heavy traffic exist, you should slow down even more. The posted speed limit is a maximum speed limit for ideal conditions only. If road hazards are present and you don't slow down, you could get a New York speeding ticket for going too fast for conditions, even if you are traveling at or below the posted speed limit.
New York police have several different methods of determining your speed before they issue a ticket. Radar is the most common. Radar devices can either be mounted inside a patrol car or housed in a portable "gun." Radar measures speed by sending out radio waves. The waves bounce off of objects such as vehicles, and the Radar device measures the return frequency of the waves, which shifts based on how fast the vehicle is going.
Police officers can also use laser to determine how fast a vehicle is going. Laser technology, also called LIDAR, measures the time it takes for a beam of light to be reflected back from a moving vehicle. The exact time will vary according to how fast the car is going when the laser beam hits it. Unlike radar, LIDAR has to be aimed at a specific vehicle. Drivers with radar detectors beware: LIDAR is undetectable with normal radar detectors, and even special LIDAR detectors won't detect it until it's too late.
In New York, police can also use aircraft such as helicopters to catch speeders. Speed can be measured from the air by watching a motorist and timing how long it takes the car to pass over two points on the ground that are a known distance apart. EZ-Pass tollbooths also have a radar system embedded in them that measures how fast you are going through the tollbooth, so make sure you slow down to a safe speed or you will receive a warning letter.
You could also have your EZ-pass privileges revoked if you continue to speed. There is a myth that the police are planning to use EZ-Pass to enforce speed limits on New York state highways, but that is actually a hoax.