That doesn't seem to be the case, if you look at the infrastructure cost breakdowns the total construction cost for phase 1 is estimated at £6.6Bn, with the remaining £9.6Bn going to things like project management, mitigation costs, and land acquisition.

If you take a look at the construction costs, of the $6.6Bn only £665 are going towards the rail and control systems. With all other items being largely the same regardless of rail speed, I have a feeling (though I could be quite wrong), that the cost difference between low and high speed is marginal.

Source: https://assets.publishing.service.gov.uk/government/uploads/...

Thanks, I really appreciate you made the effort to find some actual stats, but with respect, that doc is from march 2012. I don't know if the data is still relevant now (though it may be).

We need some solid stats by an independent party which is why I'm happy one is going to be looking into it.

FYI from that document, let me quote cos it's interesting: cost estimates in march 2012:

2.9 Route package cost summaries

2.9.1 The phase one total cost estimate is £16.3 billion within a cost range of £15.4 billion to £17.3 billion. [...]

2.9.2 The phase two total cost estimate is £17.1 billion within a cost range of £15.7 billion to £18.7 billion. [...]

2.9.3 The full Y network cost estimate is £33.4 billion within a cost range of £30.9 billion to £36.0 billion. [...]

Construction costs haven’t changed all that much since then. A significant proportion of the costs are in project management and contractual arrangements designed to shift risk away from politicians and managers. If you look at costs in France, we are about 5-10 times more expensive for a route of equivalent complexity. French digger drivers don’t earn 5x less and materials are not 5x cheaper in France, if they were French would be the language of building sites in Britain. So the costs must be coming from somewhere else; land acquisition, risk management and over complicated contracting and project management processes are my bet, based on my experience of working on large construction projects in the UK and Europe.

Most expensive TGV route so far €15m/km. ~200km London-Birmingham. Therefore ~€3bn for the high speed line itself. €5bn each end for stations? €10bn for tunnels into London? The rest spent on typical British dicking around with procurement, only people worse at wasting money on getting stuff done is the US. I wonder if it’s to do with the way we contract things? Edit: another stat says €20m/km LGV Mediterranean.

There's a lot of tunneling on HS2 - including massive underground stations at Euston and OOC, a new station in Birmingham, and tunnelling in London and Chilterns.

That has to happen whether the trains run at 180mph or 80mph.

LGV Mediterranean has to negotiate the hilly terrain in southern France. Plenty of tunnels and viaducts. €20m/km. Way less than us. The problem is with how we manage construction projects in the UK.

It's hard to compare, the UK is more densely populated, twice as high as France. My guess is a lot went into buying off property owners.

They budgeted £1.1b, but have already spent £2b

You'd be amazed just how poorly dynamite works for making miles of tunnel, in between up to 12 layers of pre-existing tunnels, through wet central London clay.

> but it is reasonable to suppose that every extra 10% in speed adds >10% in cost

I suspect the numbers are more like

60mph railway: £40b 140mph railway: £50b 180mph railway: £60b