The Brazilian city of São Paulo will see facial recognition technology applied to the surveillance systems of its subway network.

The company operating the majority of the city's subway network, Companhia do Metropolitano de São Paulo (METRO), has launched a tender for a new set-up to replace its current legacy system and a non-integrated estate of 2200 cameras, of which only some are digital.

Under the new contract, the old equipment will be phased out and replaced by 5200 digital cameras to be controlled centrally - cameras are currently operated by individual stations. Station areas will be covered as well as other areas such as tracks and maintenance centers.

Bids for the 69.5 million reais ($18.4 million) contract can be received until August 20.

With more cameras producing high definition images, the company expects to quickly detect and prevent situations such as accidents involving passengers accessing dangerous areas as well as depredation of assets.

In addition, it is expected that an integration between the new system and the police database will enable the identification of wanted criminals as well as missing persons. About 6.5 billion people used the São Paulo subway system in 2018.

Images would be stored for up to 30 days in the system to be rolled out by the subway operator. Biometric information is considered sensitive personal data under the Brazilian data protection law, to be enforced from August 2020.

Earlier this month, the Brazilian Senate passed a proposal to add protection of data in digital platforms to the list of fundamental rights and individual citizen guarantees set out in the country's constitution.

Use of facial recognition in public transport in São Paulo is not a novelty. Last year, private subway operator ViaQuatro has deployed the technology on doors under a trial intended for advertising and customer information purposes.

Doors along station platforms were fitted with screens, as well as lenses and sensors collecting data such as the number of people standing in front of the doors, their gender, and facial expressions.

The operator later canceled the trial following a civil lawsuit initiated by Brazilian Institute of Consumer Protection (IDEC), who argued that the initiative was illegal, as public transport users did not authorize the collection of data - and had no choice in the matter, given the sensors were placed on train doors.

In addition, police forces across the country have been using the technology to find criminals known to them, in events such as the Carnival in Rio de Janeiro and Salvador.