Transcript: What actually is a traffic filter? Answer: A traffic filter is a short stretch of road where a camera “reads” a car number plate. There are already around 11,000 of these cameras in use in the UK. They are used for traffic enforcement, automatic tolls, and unattended car parks. There will be 6 filter locations in Oxford. You only need a pass or exemption to drive directly through the filter. There will be no physical barriers and no need for drivers to stop. Every filter will be signposted far in advance and there will be an opportunity to turn before reaching the filter. And every part of Oxford will still be reachable by car without going through a filter!