RATP launches second hydrogen bus pilot in Paris; validates rolling stock offer for RER Line B, France February 8, 2021 | Europe News Régie Autonome des Transport Parisiens (RATP) has launched a three-month-long pilot to test a hydrogen fuel-cell bus in Paris. This is the second hydrogen fuel-cell bus pilot in the city. Portu... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password