Bristol underground rail 'could take 20 years to deliver'

Marvin Rees previously said between 65% to 75% of the routes would be underground

A "light automated metro system" for Bristol could take nearly 20 years to deliver, a council report suggests.

It said the plan could cut peak journey times from Aztec West, Emerson's Green and the airport to the city centre to under 25 minutes,

It suggests more frequent shorter trains would reduce costs as smaller tunnels and small stations can be used.

In December elected mayor Marvin Rees said three underground metro lines will be delivered "within 10 years"

Speaking then, Mr Rees said an initial study had indicated the geology of the city was suitable for tunnelling and that he was looking at options on trains and tracks, ahead of financial modelling of the project.

The draft transport strategy document suggests while an underground system is technically deliverable, the costs are significant, at about £3-4bn needed for three lines.

Rubber wheels would allow for tighter curves and steeper gradients than conventional metro systems, which is better suited to Bristol's topography.

It said sections of track can be elevated or run at grade to reduce costs, but added the system needs to be 100% segregated because the trams would be driverless.

However, it said the underground element could enable the removal of some above ground infrastructure allowing some of the streets to be reclaimed.

But critics of the scheme are sceptical it could be delivered and have warned of escalating costs.