Most speed enforcement is done with a hand held radar gun from the side of the road, by transit police. If you are exceeding the speed limit the officer will motion you to stop.  He will request the paperwork ** and will usually show you the radar gun to confirm your speed. 

Speeding fines are currently 5,000 colones up to 20 KPH over the speed limit and 20,000 colones if more than 20 KPH over the speed limit. The fine for going through a red light is 10,000 colones.  If fines are paid before the end of the year when the marchamo is purchased it is necessary to pay at a specified bank in the national banking system.  A service charge for receiving the fine payment will have to be paid in addition to the fine. 

Speed limits are usually 90 KPH on major highways in the Central Valley, and are 60 KPH at all intersections. 75 KPH is common on many secondary highways and outside the Central Valley.  School zones are usually 25 KPH when students are present. 

Most transit police are very polite, and on many occasions if they feel the driver is a confused tourist, they may simply give a warning provided all papers are in order.

** A valid drivers license either Costa Rican or foreign, and the original of the paper license if metal plates are not on the car.