Q. In a nutshell, why should we build a high-speed rail network in Britain?

We face, as a nation looking into the century ahead, two major challenges: how to compete in a globalised economy and how to address the problem of climate change. The transport sector is critical to succeeding on both agendas, and it is clear that prices will have to be increased for the use of the dominant and most environmentally damaging modes, to suppress demand levels and reduce CO2 emissions. Investment in high-speed rail is a necessary counterpart, so that domestic aviation growth can be halted, freight can be switched to rail, the under-performance of the north and the Midlands can be rectified and London and the Southeast can grow sustainably.

In addition, we know that the national transport networks are running out of capacity. This applies just as much to the principal rail routes as to our motorways and airports. Indeed, rail is growing faster than the other surface transport modes, faster than car use, for example.

As the November 2006 National Audit Office report into the West Coast Main Line pointed out, even with substantial expenditure on the route and lengthening of trains — worthwhile investments in themselves — available capacity will be fully used up within 10 years. High-speed rail is the best way to address this capacity crunch.

Q.Is there any evidence that the economy in the regions would benefit from faster connections?

Yes. A great deal of work has been done in the last few years as data on local and regional economic performance has become available. There is now clear statistical evidence that journey times to London are a critical factor in explaining variations in the economic performance of the regions.

Q. Have the benefits of high-speed rail been quantified?

Yes, in the Atkins study, which suggested that the benefits of a full network would be of the order of £90bn. This is an estimate of the economic benefits to the nation.

Q. Is this estimate still valid?

Recent work for the Department of Transport suggests that there are, in addition, benefits from so-called ‘agglomeration’ effects. These arise in particular where transport improvements are introduced to areas of dense economic activity. The agglomeration benefits of high-speed rail are likely to be very high indeed. The other principal areas of additional interest where earlier methodologies may under-estimate wider economic effects are business travel and freight, both of which are substantially assisted by high-speed rail (and probably more so than other major rail projects).

The Northern Way study by Steer Davies Gleave suggested that agglomeration benefits from north-south high-speed rail links could amount to £10 billion.

Q. Is the case for high-speed rail based on more capacity or higher speed?

Both. We need more capacity to cope with an expanding economy and to support a mode shift away from transport modes with a poor carbon imprint. We need fast journey times to attract market share (especially from air) and to deliver an efficiency gain for business.