With regard to the Railway Interface: You need to ensure you that you liaise closely with the railway organisation[s] that your works may affect,(such as Network Rail, TfL, Metro Company, Train Operators etc etc). You need to advise them of your work elements and they'll work closely to assist you in ensuring your project has minimal impact on the railway, and they will agree with you the reporting lines if an incident does occur,and who does what. What is very important is that you start discussions at the earliest possible stage - input from the 'railway people' will prove invaluable in planning the works to the benefit of all