It has emerged that passengers have been scanned as they passed through station ticket gates. A complaint has been made about alleged breaches of data protection law.

The use of AI was revealed when civil liberties group Big Brother Watch made a Freedom of Information request. It appeared that Network Rail was assessing the moods of passengers, but Network Rail said that was not so. A spokesman told the Press Association that emotions were not being analysed. Instead, the purpose of the scans was to ‘protect passengers’, and that the data could be used to ‘measure satisfaction’ and ‘maximise advertising and retail revenue’.

The system sent images for analysis by Amazon Rekognition software to record demographic details, such as a passenger’s sex and apparent age, but that part of the programme has ended. The trials were said to be part of a wider programme to use AI to tackle such problems as trespassing, overcrowding, bicycle theft and even slippery floors.

Trials are believed to have started in 2022 at Glasgow Central, Leeds, London Euston, London Waterloo, Manchester Piccadilly and Reading, which are all stations managed by Network Rail. Similar trials have apparently been carried out at Dawlish, Dawlish Warren and Marsden stations, which are managed by Great Western Railway and Northern.

Big Brother Watch head of research and investigations Jake Hurfurt said: ‘Network Rail had no right to deploy discredited emotion recognition technology against unwitting commuters at some of Britain’s biggest stations, and I have submitted a complaint to the Information Commissioner about this trial.

‘It is alarming that as a public body it decided to roll out a large-scale trial of Amazon-made AI surveillance in several stations with no public awareness, especially when Network Rail mixed safety tech in with pseudoscientific tools and suggested the data could be given to advertisers.

‘Technology can have a role to play in making the railways safer, but there needs to be a robust public debate about the necessity and proportionality of tools used.

‘AI-powered surveillance could put all our privacy at risk, especially if misused, and Network Rail’s disregard of those concerns shows a contempt for our rights.’

Network Rail responded: ‘We take the security of the rail network extremely seriously and use a range of advanced technologies across our stations to protect passengers, our colleagues and the railway infrastructure from crime and other threats.

‘When we deploy technology, we work with the police and security services to ensure that we’re taking proportionate action, and we always comply with the relevant legislation regarding the use of surveillance technologies.’