How Would We Know?

The absence of a publicly available cost benefit analysis for the proposed Bus and Train (BAT) Tunnel project in Brisbane raises a couple of obvious questions.  The first is the simplest.

The previous Cross River Rail (CRR) proposal was expected to cost around $6.4 billion to construct.  At this stage the BAT Tunnel is expected to cost around $5 billion.  Queenslanders save $1.4 billion right?

Financially they do.  But without a full CBA we cannot know what benefits are being left on the table.  If more than $1.4 billion in benefits under CRR are not realised in the BAT Tunnel we are actually reducing the net economic benefit of getting a decent public transport solution.

How would we know?