A new web app has been launched to reduce the number of people coming to harm on the railways in the South East.
Rail505.com allows Southeastern passengers to issue an alert using their smartphone.
Network Rail (NR) said the system could be rolled out across the country if the pilot scheme proves successful.
Passengers who are concerned about someone are encouraged to speak to a member of rail staff in the first instance but if that's not possible they can use the new web service to contact a control centre operated by Network Rail and Southeastern.
Reports made through Rail505.com will be kept confidential and people using it do not have to give their details.