1. F.R.A. U.S. Department of Transportation “PTC System Information ” [Online]. Available:https://www.fra.dot.gov/Page/P0358. [Retrieved 22 January 2018].
2. BS EN 50126‐1:2017‐Railway Applications.The Specification and Demonstration of Reliability Availability Maintainability and Safety (RAMS). Generic RAMS Process BSI 2017.
3. BS EN 50128:2011.Railway applications. Communication signalling and processing systems. Software for railway control and protection systems. BSI 2011.
4. BS EN 50129:2003.Railway applications. Communication signalling and processing systems. Safety related electronic systems for signalling BSI 2003.