Traffic counts are useful for comparing two or more roads, and can also be used alongside other methods to find out where the central business district (CBD) of a settlement is located.
Most modern equipment called ATR's (Automatic Traffic Recorders) store count and/or classification data recorded in memory in a timestamp or interval fashion that can be downloaded and viewed in software or via a count display on some equipment.
In some instances people either draw up a table and/or use a tally to keep a record of vehicles which pass manually as an alternative to ATR's.
These devices generally use some sort of transmitted energy such as radar waves or infrared beams to detect vehicles passing over the roadway.
Non-motorized modes of traffic are often surveyed using the same types of sensors used for motorized vehicles; in some cases tuned to be more sensitive to actuation (e.g. Pneumatic tubes, Piezoelectric, inductive loop detectors, Passive and Active Infrared, Video, Magnetometers, et al.).