1st Reason - The Australian Constitution -
►    SECT 51 and SECT 98 provides for the Australian Parliament to make laws regarding States expenditure on "...railways the property of any State"; and
►    SECT 97 'Audit' requires the Commonwealth Govt to evidence that 'Financial assistance to States' is expended cost-effectively   

SECT 96 'Financial assistance to States' of the Australian Constitution allows the Commonwealth Parliament to make financial grants to the States predicated "...on such terms and conditions as the Parliament thinks fit....".  Due to the magnitude of the on-going annual tax payer wastage evident in Annexure A and hereunder, SECT 96 behooves the Commonwealth Govt. to 'Centralise' responsibility for measuring, quantifying and ranking all proposed infrastructure projects with forecast Capex >$20m upon the Commonwealth Productivity Commission.

Below are the two aforementioned sections of the Australian Constitution (SECT 51 and SECT 98) that obligate the Commonwealth Govt to enact new laws to 'Centralise' responsibility to ensure that all future major State infrastructure projects are robust and cost-effective and do not waste the Commonwealth Govt's Public Purse:

SECT 51(i) of the Australian Constitution enables the Parliament of Australia to make laws with respect to:

        "trade and commerce with other countries, and among the States;"

SECT 51(xxxiv) of the Australian Constitution enables the Parliament of Australia to make laws with respect to

        "railway construction and extension in any State with the consent of that State;"

The meaning of trade and commerce is clarified in the below extract of SECT 98 of the Constitution includes navigation and State railways:

        "The power of the Parliament to make laws with respect to trade and commerce extends to navigation and shipping, and to railways the property of any State."