ANPR Camera Errors & Double-Dipping Explained

ANPR (Automatic Number Plate Recognition) cameras are now standard in most private car parks across the UK. While they're generally reliable, they make mistakes – and those mistakes can lead to unfair parking charges.

This guide explains how ANPR systems work, common errors, and how to challenge a charge when you believe the camera got it wrong.

How ANPR Parking Systems Work

ANPR cameras photograph your vehicle's number plate when you enter and exit a car park. The system:

1. Captures your registration at entry
2. Records the timestamp
3. Captures your registration at exit
4. Calculates your total stay duration
5. Compares this to the parking conditions (time limit, payment made, etc.)

If the system thinks you've overstayed or not paid, it triggers a Parking Charge Notice.

The Double-Dipping Problem

One of the most common ANPR errors is called "double-dipping". Here's how it happens:

Example scenario:

• 9:00am – You enter the car park (camera records entry)
• 10:30am – You leave to go to work (camera FAILS to record exit)
• 5:00pm – You return to the same car park (camera FAILS to record re-entry)
• 6:00pm – You leave for the evening (camera records exit)

Result: The system sees entry at 9:00am and exit at 6:00pm = 9-hour stay, triggering an overstay charge.

In reality, you made two separate short visits that were perfectly compliant.

Other Common ANPR Errors

1. Missed Entry or Exit Scans

Cameras can fail to capture your plate due to:

• Dirty or obscured number plates
• Poor lighting conditions (night, rain, glare)
• Camera malfunction or maintenance
• Tailgating (following another car too closely)
• Technical glitches in the system

2. Misread Number Plates

ANPR software occasionally misreads characters, especially:

• Similar letters/numbers (O vs 0, I vs 1, B vs 8)
• Unusual fonts or spacing on plates
• Damage or wear to the plate

3. Time Calibration Issues

If camera timestamps are incorrect, your calculated stay time will be wrong. This is rare but does happen.

How to Challenge an ANPR Parking Charge

If you believe the ANPR system made an error, your appeal should:

1. Request All ANPR Evidence

Ask for:

• All ANPR images of your vehicle
• Exact timestamps for each capture
• Proof of system calibration and maintenance records
• Error rates for the ANPR system

2. Provide Counter-Evidence

Gather your own evidence showing your actual movements:

• Bank/card statements showing purchases with timestamps
• Receipts from shops visited that day
• Work timesheets or appointments
• Mobile phone location history (Google Timeline, etc.)
• Witness statements if applicable

3. Challenge the Burden of Proof

Under the Protection of Freedoms Act 2012 Schedule 4, the burden is on the operator to prove the contravention occurred. If their evidence is incomplete or contradictory, they may not be able to enforce the charge.

What the Law Says About ANPR Evidence

ANPR evidence is not infallible, and operators must:

• Clearly display that ANPR is in use
• State on signage that ANPR is used to "determine length of stay"
• Maintain accurate and calibrated systems
• Retain evidence to prove the alleged contravention

If signage doesn't clearly explain how ANPR is used, or if the operator cannot produce complete evidence, your appeal is stronger.

Related Guides

Grace Periods Explained | Council vs Private Tickets | ParkingEye Appeal Guide