BRITAIN's railways are facing a dilemma. In the 2011-12 financial year the network carried almost 1.5 billion passengers, nearly double the figure for 1994-95, immediately prior to the privatisation of British Rail. Long distance ridership has grown from 54 million to 125 million over the same period and the upward trend, which has endured through four years of economic stagnation, looks set to continue.

With broad political and industry consensus that long-term capacity needs could only be satisfied by the construction of a new line, the government unveiled proposals in March 2010 for a High Speed 2 (HS2) Y-shaped high-speed network with an initial 190km phase linking London and Birmingham, which would be followed by extensions to Manchester and Leeds.

Planning work is now advancing rapidly on the first stage, and although the government has decided to repeat consultation on property compensation following a High Court ruling, a hybrid bill is still on schedule to go before parliament in October. If the bill becomes law, which is expected by 2015, it will grant powers for the construction and operation of Phase 1, allowing civil works to begin in 2017.

On January 28 the government unveiled the Department for Transport's (DfT) preferred route for the second phase of the project, which will involve the construction of two branches totalling 338km extending north to Manchester and Leeds. Although subject to revision, this provides the first glimpse of the government's vision for how high-speed rail will reach northern England.

HS2-mapThe western branch will continue the line beyond the northern extremity of Phase 1 near Lichfield, passing east of Stafford and roughly following the route of the West Coast Main Line (WCML) as far as Crewe, where there will be a link to the existing line to allow high-speed services to serve Runcorn and Liverpool. A triangular junction will be built east of Manchester which will allow services to run east to Manchester Airport and the city centre, or north to join the West Coast Main Line (WCML) south of Wigan. A station will be constructed near Manchester Airport, which will be located close to the M56 highway, and this will serve as a hub for Cheshire as well as the airport. The line will then enter a 12km tunnel, emerging near Longsight depot and following the existing line towards Manchester Piccadilly. High-speed services will terminate at a new central station, which will be built alongside the existing Piccadilly station. The length of the DfT's preferred initial alignment for the western branch is 152km, including links to the WCML.

Eastern branch

From a junction east of Sutton Coldfield, the eastern branch will follow the M42/A42 highway, passing beneath East Midlands Airport in a 2km tunnel before crossing the Midland Main Line and the River Trent to reach a new East Midlands Hub station, which will be built on the Toton freight yard site between Nottingham and Derby. This will be linked to the cities by conventional rail services with a journey time of 12 minutes and 15 minutes respectively. An extension of the Nottingham light rail network from its nearby western terminus at Toton Lane is also being discussed, which would give the city's western suburbs direct rail access to the Hub station.

Even with a change at East Midlands Hub, London - Derby journey times would be cut from 1h 44min to 1h 8min while London - Derby would fall from 1h 31min to 1h 11min. But as with other stations on the route, the journey time benefits will only be optimised if connecting regional services are appropriately configured. Toton is not on the main line between the two cities and as such would require the diversion of regional services (incurring a time penalty for non-HS2 passengers) with a reversal at Toton, or the operation of a dedicated shuttle.

North of Toton the line will closely follow the M1 highway into South Yorkshire, where a new station at Meadowhall will serve the Sheffield area. Meadowhall is already an interchange between mainline services and the Sheffield light rail network, with services to a broad range of destinations across South Yorkshire and further afield. The planned Sheffield - Rotherham tram train could also be extended to serve the new station.

The decision not to serve Sheffield city centre has been a controversial one, although the DfT says Meadowhall will be "as little as five minutes" minutes by train from the city's main station. The DfT suggests a new cross-city shuttle service could be introduced to link Dore & Totley in the south of Sheffield with the city centre and Meadowhall.

The line will then continue east of Barnsley and Wakefield to reach a junction southeast of Leeds, with one branch heading into the city centre to serve a new station at New Lane, a short walk from the existing mainline station, and the other curving east to provide a connection with the East Coast Main Line south of York. The total length of the eastern branch will be 186km.

Journey times between Leeds and London will be cut from 2h 12min to 1h 12min, while Manchester - London will be almost halved from 2h 8min to 1h 8min. The line will also have a major impact on journey times between cities in northern and central England. For example, the 110km journey between Leeds and Nottingham currently takes up to 1h 45min, but this will be cut to 46 minutes by HS2. Stations at Leeds, Sheffield, East Midlands and Birmingham will each be separated from the next by journey times of under 20 minutes. According to the DfT, journey times between Manchester and Birmingham will fall from 1h 8min to 41 minutes, while Leeds - Birmingham will be cut from 1h 58min to 57 minutes. Cities further north, such as Newcastle and Durham, will also benefit from a 30 minute reduction in journey times to London, while the fastest services from Edinburgh and Glasgow will be reduced to around 3h 40min. The Scottish government is developing its own plans for an Edinburgh - Glasgow high-speed line and is eager to see a commitment from London to extend HS2 further north.

In addition to speeding up journeys and releasing capacity on the conventional network, HS2 is expected to encourage significant modal shift to rail. The line is forecast to carry up to 5.4 million passengers a year who might otherwise fly, and take 9.8 million journeys off the road network.

Public consultation on Phase 2 was due to begin next year, but the process has been brought forward to start this year and secretary of state for transport Mr Patrick McLoughlin asked the DfT to look at options to speed up implementation of the project. The final route will be selected by the end of next year and both branches are due to open by 2032.

The total capital cost of building the complete Y network is expected to be around £33.4 billion at 2011 prices, although this figure includes the 40% optimism bias imposed on major projects by the Treasury. At present values, it will generate benefits of up to £47 billion and fare revenues of up to £34 billion over a 60-year period. According to HS2 Ltd, the public company responsible for developing the new railway, the cost of Phase 2 is estimated to be around £17.1bn.

This cost estimate does not include the proposed branch to London's Heathrow Airport. Last year the government said Heathrow should be linked directly to HS2, but the plans were subsequently put on hold pending the conclusions of a report by the Airports Commission on connections to major international airports, which is due to be completed in 2015. The DfT says the Heathrow link will not be included in the forthcoming Phase 2 consultation, although if required it could still be included in the legislation authorising Phase 2 without any impact on the construction schedule. According to the DfT the planned high-speed station at Old Oak Common in west London will be just 11 minutes by train from Heathrow, which will be served by frequent Crossrail services from 2018.

HS2 has the potential to transform the operation of Britain's overcrowded network, segregating long-distance services from regional and freight traffic and easing the pressure on many of the worst bottlenecks in the system. The key to the success of the project will be how the new infrastructure is integrated with the existing network, and how capacity freed up on conventional lines will be used. At this early stage in the process such details are understandably sketchy, but they will be crucial to realising the full benefits of this potentially transformational project.