How to choose an ANPR camera for highways

Why highway ANPR is different

A city CCTV camera records a scene for people to watch. A highway ANPR camera must turn a vehicle moving at expressway speed into a sharp image of a small plate, often at night, in rain or with headlights shining into the lens. It usually sits on a gantry far from the control room, so it must also work through power cuts and network outages. Those conditions change which specifications matter.

On Indian highways the traffic mix is wide. Fast cars share lanes with slow trucks, buses, tractors and two-wheelers. The camera must read all of them, including plates that are dirty, bent, hand-painted or in two lines.

The specifications that matter

Shutter type and exposure

A rolling shutter reads the sensor one row at a time, so a fast vehicle moves during the readout and the plate characters lean or stretch. A global shutter captures the whole frame at once. Exposure time controls motion blur within the frame. A vehicle at 100 km/h moves about 2.8 cm every millisecond, so even 1 ms of exposure is visible at plate scale. Ask for both the sensor type and the exposure used at night.

For the engineering detail behind this choice, read why global shutter matters for ANPR on our blog.

Infrared illumination

A short exposure lets in little light, so night reads depend on IR illumination. Ask for the IR range in metres, the wavelength, and whether the IR is pulsed in step with the shutter. Pulsed IR gives a bright, short flash without the heat of a continuous lamp.

Pixels on the plate

Resolution alone says little. What matters is how many pixels fall across the plate at the read point, which depends on the sensor, the lens, the mounting height and the distance. A narrow lens on a modest sensor often beats a wide lens on a high-resolution sensor. Ask the vendor to state the pixels across a standard plate for your gantry design and the number of lanes each camera covers.

Plate formats and vehicle classes

Indian plates include HSRP and older plates, Bharat series, commercial and electric vehicle colours, single-line and two-line layouts, and hand-painted characters. Ask what the model was trained on, and ask for sample reads of each format captured at speed.

Processing and integration

Decide where the plate is read. A camera with an on-board processor sends events and evidence images instead of continuous video. A camera that streams to a server needs a reliable link. Check the interfaces: ONVIF profiles, RTSP streams, and a documented way to send plate events to your command centre and e-challan workflow.

Enclosure and power

Look for an IP rating suitable for monsoon and dust (IP66 or better is common), an operating temperature range that covers Indian summers inside a sealed housing, and surge protection on power and data. Check power draw with IR and heaters on, against the PoE budget or cabinet supply.

Highway-grade vs general-purpose cameras

Certifications and documents

Indian highway projects usually ask for independent evidence. For CCTV and ANPR cameras, that means testing under the BIS Compulsory Registration Order and STQC certification for public procurement. If the camera also measures speed, ask for test results from a recognised centre such as NATRAX, and for radar, the Legal Metrology verification required from 1 July 2025. On national highways, check the system against NHAI's ATMS Standards and Specifications 2023. In every case, ask for the document for the exact model number offered, and check that it is current.

Field trial plan

A datasheet cannot tell you how a camera performs on your road. Plan a trial before the order.

• Site: a live lane on the target road, at the planned mounting height and angle.
• Duration: at least a week, covering day, night and, if possible, rain.
• Ground truth: a manually checked plate for every vehicle in a sample period.
• Metrics: detection rate (vehicles seen) and read rate (plates read fully correct), reported separately.
• Breakdown: by vehicle class, by day and night, and by speed band.
• Evidence: review a random sample of evidence images for clarity and correct time and location stamps.

Procurement checklist

• Sensor type stated as global shutter, with the night exposure time.
• IR range in metres, wavelength, and whether it is pulsed with the shutter.
• Pixels across a standard plate at your mounting point, and lanes covered per camera.
• Sample reads for HSRP, older, Bharat series, two-line and two-wheeler plates, at speed and at night.
• Read rate defined (whole plate correct) and reported by condition, not as one number.
• On-board processing and local storage during network outages.
• ONVIF profiles, RTSP streams and a documented event interface for your command centre.
• BIS registration and STQC documents for the exact model, plus speed test and Legal Metrology documents where speed is measured.
• IP rating, temperature range, surge protection and power draw with IR on.
• Remote firmware and model updates, and the vendor's support process for gantry sites.
• Total cost over five years: hardware, poles or gantry share, power, connectivity, maintenance and software.

How Stellarview approaches it

The Recon Global Shutter Camera is Stellarview's highway ANPR camera. It uses a global shutter sensor, built-in IR, and an on-board edge processor that reads plates and detects violations at the gantry. It supports ONVIF Profiles S, T, M and G. Its certifications are listed on the product page and on why STQC matters. See the highways and expressways solution for complete corridor designs.

Frequently asked questions