Plans for a tube-style underground in Bristol have been vetoed by Metro Mayor Dan Norris at a key vote. 

The West of England Combined Authority (Weca) was due to decide on how to progress plans on its proposed mass transit system at a meeting today. But the future for the "Future4West" scheme remains uncertain after region's political leaders failed to come to an agreement.

Mr Norris used his veto to prevent any further consideration of a tunnelled underground along three routes through the city — overruling Bristol Mayor Marvin Rees and the leaders of South Gloucestershire and Bath and North East Somerset Councils and going against the recommendation of his own transport chiefs.

Mr Norris said: "I won't waste a penny more of taxpayers' money on an underground. I voted for overground options only because I believe an underground to be unaffordable and unrealistic."

But the three council leaders blocked all moves to only continue with an overground and cut-and-cover mass transit system — leaving the vote in a stalemate and the future of Bristol transport in limbo.

Mr Rees said: "We need to keep all options on the table until the evidence tells us it's not possible."

Weca estimates that a tunnelled tube-style underground could cost between £15bn and £18bn — leading opponents of the plan to dub it "fantasy" — although Mr Rees claimed that subsequent Weca papers had suggested it could be delivered 40-50% cheaper.

Meanwhile, a cheaper mass transit system based mainly overground with some cut-and-cover tunnels could include massive roadworks — including digging up stretches of Gloucester Road and Church Road.

Mr Rees told the meeting that the idea of asking a future Bristol City Council administration to close these roads made the scheme "undeliverable." He said: "Liveable neighbourhoods have been challenging enough. This would be an intervention of epic proportions."

The meeting was also warned that dropping consideration of tunnelled underground options at this stage could cost them in the long run. Richard Bonner, chair of the Local Enterprise Partnership, told the committee: "If you think about Stokes Croft, Gloucester Road what that means for roadworks impeding the ability of traders to have sustainable businesses for two or three years of disruption, there's a significant risk that some of those traders will find that they are not able their sustain their businesses."

Mr Bonner said that the combined authority could save £10k to £30k if stopped investigating underground options, but that they could then face more the costs and delays caused by legal challenges from affected businesses if they dug up the roads without fully considering the alternatives.

South Gloucestershire Council leader Claire Young said she was sceptical about a fully underground option but said "this is not about that." She said: "We have very very clear legal advice — we also have the views of the business community — all very clearly saying we need to keep all options on the table."

But nothing is on the table until the region's political leaders can agree.