Service tax on construction of railway siding in a public ltd co. plant by a pvt co.

In the Para 14 of Notification No.25/2012 - service Tax dated 20th June 2012 notifies the negative lists and according to that the following are covered and no service tax should be applicable on " 14. services by way of construction , erection, commissioning, or installation of original works pertaining to, - ( a ) an airport, port or railways, including monorail or metro ". From the above it is not clear whether on construction of Railway siding inside a Power Plant by a contractor ( Pvt company ) will be exempted from paying service tax or not. It may please be clarified with reference to past incident/ clarifications of service Tax department if any.