What it means
There are two main methods. Spot speed is measured at one point, usually with radar, camera analytics, or both. Average (section) speed is calculated from the time a vehicle takes to travel between two ANPR points a known distance apart. Spot speed catches sudden speeding at a hazard. Average speed discourages braking only at the camera.
The evidence record matters as much as the measurement. It should show the vehicle, the plate, the measured speed, the lane, the time and the location.
How it applies in India
The Ministry of Road Transport and Highways allows challans for speeding based on footage from electronic enforcement devices with an electronic stamp of location, date and time (Rule 167A, August 2021). From 1 July 2025, rules under the Legal Metrology (General) Rules, 2011 require radar speed measurement equipment to be verified and stamped by Legal Metrology authorities. NHAI's 2023 ATMS standards integrate VSDS into VIDES. Stellarview VSDS combines a Recon camera with a 4D Doppler radar.