TMB says the authorisation makes it the first European rail operator to be formally recognised as an ISA and the first to be granted the operations ISA, allowing it to carry out railway safety assessments and audits throughout the European Union (EU) and countries which have adopted EU railway standards

To gain accreditation, TMB had to comply with EC Regulation 352/2009, which came into force in July 2010 and covers the adoption of common safety methods on risk evaluation and assessment for railway systems. This requires auditing organisations to demonstrate that they possess the necessary technical capability and independent judgement, as well as well-trained professional auditors with appropriate experience and knowledge of the assessment process.