The project received Royal Assent but issues arose between Bristol City Council and South Gloucestershire, the latter wishing for the route to be extended to serve Cribbs Causeway.
As the extension was deemed unfeasible, South Gloucestershire withdrew support, and in March 2004, Bristol Council announced that the Supertram project would be cancelled.
The MetroBus network began construction in 2015 and opened in stages through 2018 and 2019, at a cost of £230 million (including work which benefitted other road users).
No mention of light rail was made in these subsequent years until November 2016, when the West of England LEP began a consultation process on their Transport Vision Summary Document, outlining potential light rail/tram routes from the city centre to Bristol Airport, the eastern and north west fringes of the city, and a route along the A4 road to Bath.
[6] In July 2017, a leaked draft of a document due to be published in October 2017 suggested an underground rail network around the most built-up areas of the city as one of many solutions to congestion said to cost £8.9 billion.
[7] The full document had detailed analysis of a potential mass transit network with underground sections, with the route to the airport being determined as the best value for money, and most meeting the needs of this particular transport corridor.
"[14] In February 2019, the West of England Combined Authority agreed to spend £200,000 to further develop an outline business case for the network, under guidance from the Department for Transport.
Following a meeting in July 2019, WECA awarded another £1.3 million to further develop mass transit proposals;[18][19] to look in more detail at demand, the scope of the project, and its potential outputs and benefits.
Bristol City Council's Growth and Regeneration Scrutiny Commission the same month noted the network's "final proposal could be a mixture of on-street and underground running based on corridor characteristics and demand".
"[21] The Bristol Transport Strategy published the same month gave mention to the potential use of VAL technology, following the example of light metro systems in Rennes, Toulouse, Turin, Lille and Taipei.
[22] As part of forward plans for upgrades to Bristol Temple Meads railway station, Network Rail confirmed in early 2020 that it was assessing potential underground entrances to the mass transit system.
In the Jacobs report, four mass transit corridors were analysed in further detail; radial routes from Bristol city centre serving southern, northern, northeastern and southeastern areas.
An entirely underground route, at a cost of £890 million, would be 7.5 km (4.7 mi) in length, starting at Temple Meads and serving St Philip's Marsh, Arnos Vale, Brislington, the current Brislington Park & Ride (which is due to be relocated and replaced with new homes), a new Park & Ride at the Hicks Gate roundabout, and a terminus at Keynsham railway station.