Network engineers face some big decisions before HS2 becomes a reality. Stuart Nathan reports.
The die is almost cast. Buoyed up by the success of the Channel Tunnel Rail Link and finally fed up of taking three hours to get from London to Manchester, public and political opinion is now swinging behind the concept of a new, high-speed rail network for the UK.
The concept is in its early phase, and debate is currently centred around the route that the first of the new lines — generally known as High Speed Two or HS2 — will take. But building a high-speed rail line, installing signalling and control systems, and equipping it with rolling stock is, over and above all, an engineering challenge. Should HS2 be approved, construction is likely to begin around 2017, but it’s not too early to take a look at the technological challenges that a new network will face.
One of the major decisions for a high-speed line is very simple: how fast will the trains go? For most high-speed lines around the world, the standard speed is around 320kph (200mph), but the company set up to consider the case for HS2 (confusingly, also called HS2) is aiming at a faster target — 400kph. This, said HS2 chief executive Alison Munro, is a departure from HS1, the Channel Tunnel Link, whose Eurostar trains have a maximum design speed of 300kph.
‘We will be trying to achieve a maximum design speed of 400kph, to ensure that the line could keep pace with advances in train technology,’ Munro added. This in itself has implications for the design of the line. One of the reasons for the slower maximum speed on HS1 is that it is a mixed-use line, with the fast Eurostar trains sharing the line with the slower Javelin trains, providing a 230kph commuter service to towns in Kent.
‘HS1 can operate like this because the Eurostar trains leave enough residual capacity on the line,’ said Munro. ‘And if a new high-speed line was built between London and the West Midlands, it too would connect up with the existing network to allow services to run north of Birmingham. But, in order to make the most of the train paths available and to maximise journey time benefits, all the trains would need to operate at high speed over the new section of line.’
In order to accommodate the possibility of 400kph trains, HS2 is considering building in features such as deceleration lanes for major junctions, to maximise the capacity of the line. ‘In addition,’ said Munro, ‘while we are identifying a buildable route based on two tracks, part of our remit requires us to assess the potential of increasing the number of tracks to four.’
But the 400kph speed isn’t a consensus. Jim Steer of Greengauge21, a research group focusing on high-speed rail, thinks this might be a case of over optimism. ‘HS2 is talking about 400kph as futureproofing and there might be some wisdom in that,’ he said. ‘But in our recent report on a strategy for a high-speed network, we did our analysis on 320kph, because given the knowledge of train control systems, going any faster would entail a step change that, at the moment, nobody knows how to achieve.’
The 320kph operating speed allows 16 trains per hour to run on the line, Steer explained. ‘In practice, it would be 15 trains per hour, to allow for a “breather slot” for performance reliability reasons,’ he added. ‘But if you go faster than 320kph, you start to have problems with the response time of the signalling systems, and you have to leave longer gaps between the trains, even though they’re going faster.’
Greengauge21 is recommending the use of a standard European gauge for the trains, a UIC (a French acronym for International Union of Railways) GC gauge that is capable of taking the largest high-speed trains currently available, the ‘duplex’ or double-decker rolling stock. With the exception of HS1, the British train system hasn’t used UIC gauges before, but Bruno Sol-Rolland, Alstom’s vice-president for mainline products and a veteran of UK rail projects, explained that there could be advantages to switching over.
‘There are two aspects to this,’ he said. ‘If they want to go to a UIC gauge and TSI compliance, which is a standard used within Europe to make sure trains can run from one country into another, then there might have to be major works on infrastructure, such as tunnels and platforms. But there would be advantages in terms of cost. We could use our existing models of trains, for example, with only very small adjustments, rather than having to develop a specific model for the UK. Also, if applying for EU funding, you would have to comply with certain specifications, and if you weren’t TSI compliant, then you wouldn’t get funding.’
As far as HS2 is concerned, the main consideration is whether the new line would operate completely on its own — that is, its trains would run only on the new high-speed line — or if they would run directly onto the existing network to serve other destinations. This is especially important if the line were to be built and brought into operation in stages: would you have to change at Birmingham from a high-speed train to a standard train to carry on to Glasgow, or would your train go all the way, slowing down in the middle? In the latter case, the current gauge would have to be used throughout and the trains would have to have a bespoke design.
There is, of course, a wealth of experience for the UK to call upon in high-speed rail. France, Germany, Italy, Spain and Japan all have high-speed networks at various stages of development, but as every country has different demands for the rail service, it’s difficult to draw direct comparisons. ‘In Japan, where the first Shinkansen was constructed between the densely populated metropolitan areas of Osaka and Tokyo, the sheer number of passengers has permitted a high-frequency service, departing every three to five minutes and exceptional punctuality as it is segregated from other networks and excludes freight,’ Munro said.
‘In France, the network has developed around Paris as a hub and the hybrid TGV trains that operate have the flexibility to run on the classic network, allowing a wider range of towns and cities to benefit from high speed along the principal trunk routes. Germany’s network is more like a web, joining up its principal cities and caters for a variety of trains all on the same lines. It’s too early to say with certainty how a UK-wide network would develop, but it is likely to take on elements from each of those models.’
As far as the trains themselves are concerned, Sol-Rolland said that the biggest differences with current high-speed stock is likely to be in the level of passenger service. ‘There’s a lot of demand for services such as broadband internet and movies, which we’re working on,’ he added. ‘There are ongoing tests with trains using an onboard antenna pointing directly at the satellite for internet services; by the time the UK network is built, they should be fully available.’
The data – a second high-speed line would transform UK rail
A new high-speed rail network for the UK would see journey times cut dramatically. Trains with a top speed of 320kph could whizz from London to Birmingham in 46 minutes, and could make the trip to Edinburgh and Glasgow in just over two hours, making rail a true competitor to the air shuttle.
Like all major infrastructure projects, a new network would be built in stages, and the first of these, HS2, will run from London to the West Midlands. HS2’s report will also cover three ‘strategic corridors’ to take the line further north in stage two. The cost for the complete line is currently estimated at £34bn, although construction is unlikely to start until around 2017. According to Jim Steer of Greengauge21, a complete network could take around 25 years to complete.