It has more than 100 member companies, active across the whole range of railway supply. That range is exceptionally diverse and includes many skills and resources which were previously part of the national railway undertaking but which now operate commercially in the private sector. RIA members represent the greater part of the UK railway supply industry by turnover.
Most large firms are members, as well as a wide range of smaller companies.
RIA was a founder member of the Railway Forum, the organisation representing the whole of the UK railway industry, and plays an active part in its affairs. RIA also organises British industry's participation in the development of national and international technical standards for railway equipment.