Network Rail (NR) and the wider rail industry collaborate to implement necessary mitigations against trespass and manage any disruption if these incidents occur. In the event of a trespass incident, operators and NR will issue extensive passenger communications, advising passengers of disruption and available options. Where disruption is predicted, or has begun to occur, contingency timetables will be implemented to ensure the maximum service possible can be operated. Every rail operator that manages stations has an obligation to obtain and maintain Secure Stations Accreditation, assessed by BTP, for a number of their stations. The scheme requires operators to demonstrate how they ensure their station has a defined perimeter through the use for example, of walls, fencing or hedging, as well as ensuring the built environment allows appropriate visibility and sightlines, has good CCTV coverage, and has anti-trespass warning notices displayed. Trespass can be either criminal, or because somebody is vulnerable and in crisis, therefore every operator is also required to obtain and maintain accreditation to the Safeguarding on Rail Scheme (SRS), again assessed independently by BTP. The scheme requires operators to demonstrate how they are actively supporting vulnerable people on their network.