10 January 2012 Last updated at 10:27 ET

HS2 go-ahead sees mixed reaction

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The government has approved plans for a new high-speed rail link between London, Birmingham, Leeds and Manchester known as HS2.

Ministers say the scheme will have massive economic benefits, although the plans have proven controversial and have spawned a number of protest groups. So what exactly does it involve?

What is HS2?

The initial plan is for a new railway line between London and the West Midlands, carrying 400m-long (1,300ft) trains at speeds of up to 250mph - faster than any current operating speed in Europe. They would travel up to 14 times per hour in each direction. This would be followed by a Y-shaped extension taking services from Birmingham to Manchester and Leeds. The government said there would be intermediate stations in the East Midlands and South Yorkshire. A consultation begins on the second phase in 2014.

What does it mean for passengers?

The Department for Transport says the project will cut Birmingham-London journey times from 1hr 24min to 45min. After the second phase, Manchester-London journeys would take 1hr 8min (down from 2hr 8min), and Birmingham-Leeds 57min (from 2hr). This would effectively reduce journey times between London and Edinburgh and Glasgow by an hour to 3hr 30min.

Any other travel benefits?

The government believes its creation would free up capacity on over-crowded commuter routes. It also estimates the new line could transfer 4.5 million journeys a year from the air and nine million from the roads, removing lorries from busy routes. The Department for Transport's consultation document says HS2 would offer potential for new direct services to Europe, via the UK's other high-speed line - the Channel Tunnel Rail Link - and to Heathrow.

When will it open and how much will it cost?

The government insists HS2 would use a similar fare structure to existing operators

The London-West Midlands phase is expected to be built between 2016 and 2026, followed by the onward legs to Manchester and Leeds by 2032-33. Ms Greening says the whole HS2 project will cost £32.7bn at present values and deliver benefits worth £47bn, although opponents dispute these claims.

What about fares?

The government says its proposals "assume a fares structure in line with that of the existing railway" and that HS2 could generate sufficient demand and revenues without needing to charge premium fares. It estimates fare revenues of up to £34bn over a 60-year period.

Why are ministers so keen?

The government argues that Britain's rail network is reaching capacity and that infrastructure owner Network Rail says the southern section of the West Coast Main Line - currently the quickest rail route between London and Birmingham - will be "effectively full" by 2024.

Is there an economic argument?

The government claims the London-West Midlands section alone would create around 40,000 jobs. Groups such as the Campaign for High Speed Rail say there will be added knock-on benefits, while some MPs believe it could be a catalyst for economic growth and help rebalance the economy between the north and south.

The plan has attracted fierce criticism from some of those living on the intended route

What were the arguments against HS2?

More than 70 groups oppose HS2. One, StopHS2, argues that England's north and Midlands will lose out to London, rather than benefit, and that projections do not take into account competition from conventional rail. Others object on the grounds that it will cut through picturesque countryside.

Eighteen councils along the route which are against the scheme, known as the 51m group, say taxpayers cannot afford the line, and that it will increase greenhouse gas emissions. Some MPs, including many Conservatives, are worried about its effects on their constituencies.

How has the government addressed environmental concerns?

The transport secretary has announced extra tunnelling and "cutting" through hills from London to Birmingham, which she said would "mitigate" more than half the route. There are new or extended tunnels at Amersham in Buckinghamshire; Ruislip in north-west London; Greatworth in Northamptonshire; Turweston in Buckinghamshire; Chipping Warden and Aston le Walls in Northamptonshire; Wendover in Buckinghamshire; and Long Itchington Wood in Warwickshire.

Were there any alternatives to HS2?

A Department for Transport-commissioned study into alternatives identified options including increasing capacity by lengthening existing trains and platforms (at a cost of £3.5bn), remodelling infrastructure to increase service frequency (£13bn) and both increasing capacity and reducing journey times by bypassing slow track sections (£24bn). But infrastructure owner Network Rail says these would cause massive disruption to passengers for limited improvement.

French passengers have enjoyed high-speed rail travel for three decades

How does HS2 compare with current services?

Most of the UK's main line inter-city services are limited to 125mph (201km/h), with lower limits in places, while ageing diesel locomotives operate in many areas such as the East Coast Main Line and Great Western Main Line. Eurostar services operate at 186mph (300km/h) on the 68-mile (109km) London to Folkestone line, HS1, which is shared by 140mph (225km/h) Kent commuter services.

And with mainland Europe's railways?

France's flagship TGV services have been touching 200mph (322km/h) since 1981. They serve not only regional towns but those in Italy and Switzerland, while the 186mph (300km/h) Thalys uses the same track to serve Belgium, the Netherlands, France and western Germany. European Union efforts to ensure compatibility mean services like the German-built InterCity Express, which can reach 180mph, serve major destinations across much of western Europe.

The route's key sticking points

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Green-belt land

The planned route encroaches on green-belt land in a number of areas, including around London and Birmingham.

The Campaign to Protect Rural England argues plans for new out-of-town parkway stations would have a "devastating" effect on green belt and that the economic benefits would be a fraction of those that would be achieved from town centre stations.

The campaign group wants, in particular, changes to the proposed Birmingham interchange station, which it says will "encroach into the green belt next to Birmingham Airport".

Wildlife sites

County wildlife trusts are concerned the proposed route will pose a threat to wildlife. They estimate more than 150 nature sites could be affected, including 10 Sites of Special Scientific Interest (SSSIs).

Four nature reserves will be directly impacted, they say. They are Finemere Wood Nature Reserve and the Calvert Jubilee Nature Reserve, managed by the Berks, Bucks and Oxon Wildlife Trust, Broadwater Lake Nature Reserve, managed by Herts and Middlesex Wildlife Trust, and Park Hall Nature Reserve, managed by the Wildlife Trust for Birmingham and the Black Country.

The government has said that extra tunnelling and route amendments mean that the impact of more than half the route will now be mitigated. However, the wildlife trusts say this could actually make the damage to wildlife worse.

Heathrow

The second phase of the government's plans include a possible future spur to Heathrow Airport in west London.

The HS2 line from London to Birmingham is expected to open in 2026, followed in 2032-33 by high speed links to Manchester, Leeds and Heathrow.

However, in November, the Commons Transport Committee said a case for routing HS2 via Heathrow had not been set out clearly and needed further analysis.

Labour, which supports HS2, has suggested the first phase main route should actually travel via Heathrow, creating a hub at the airport and thus making it easier for travellers from south-west England to get on fast trains to the north. It would also protect the most sensitive parts of the Chilterns, the party says.

The Chilterns

The proposed HS2 line crosses the Chilterns area of outstanding natural beauty (AONB). Environmental and local campaigners say the picturesque landscape will change forever if plans are approved.

The government was due to make an announcement on HS2 in December, but delayed it to incorporate miles of extra tunnelling to try to appease opponents. It has added 7.5 miles of tunnelling and 3.5 miles of deep cuttings along the 13 miles of proposed line through the Chilterns AONB.

The Campaign to Protect Rural England has said additional tunnelling would be "essential" if HS2 is to be built through the area.

Conservative heartlands

A number of Conservative MPs have expressed concerns about the rail link, which passes through Tory heartlands. Welsh Secretary Cheryl Gillan has been one of the most vocal Conservative critics and says she is prepared to resign over the project that cuts through her Chesham and Amersham constituency.

Dan Byles, Conservative MP for North Warwickshire and Bedworth, and Andrea Leadsom, Conservative MP for South Northamptonshire, have also voiced concerns.

To try to win over critics, ministers have added a overall total of eight miles of tunnelling along the route - mostly in the Chilterns. The changes include extended tunnelling near Amersham, in Mrs Gillan's constituency, near Ruislip in north-west London, Turweston and Wendover in Buckinghamshire, Greatworth, Chipping Warden and Aston le Walls in Northamptonshire, and Long Itchington Wood in Warwickshire.

Euston station

Campaigners fear the planned remodelling of Euston Station will lead to disruption that could last for many years.

Last year, a study from The TaxPayers' Alliance said passengers would face slower and less-frequent services if the scheme went ahead. Creating the London to Birmingham HS2 would mean Euston station in London "becoming a building site for seven years", it said.

Labour's Frank Dobson, MP for Holborn and St Pancras, told MPs the station was already overcrowded and lacked the infrastructure in surrounding streets to be the terminus for a high-speed rail link. The proposals would also mean the demolition of the homes of more than 350 of his constituents, he said.

The government has said its revised route halves the number of homes affected.