Benefits at risk from future changes

The benefit: cost ratio (BCR) for HS2 has fallen from 2.3:1 to 2.2:1 between 2013 and 2015’s assessment of the full network business case, according to the National Audit Office.

And because two-thirds of economic impacts will only be realised on completion of Phase 2, NAO says the BCR is likely to change further as new risks, opportunities and cost pressures emerge, as well as the impact of HS2 on existing and future rail franchises.

Other factors such as increased capacity on roads, new technologies and long-term trends in fuel prices could also affect demand growth, says the NAO. And decisions about the capacity and the journey experience on the trains, as well as any scope changes to Phase 2, could also have an impact.

The next iteration of the business case is due in autumn 2016, along with the route announcement for Phase 2.