die belebende Bedenkung

Screen if you want to go faster

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Felix Schmid, Professor of Civil Engineering at the University of Birmingham, outlined his views on tunnels and other engineering challenges of HS2 at The Conversation. According to the Professor, the real achievement of the designers and builders of Japan’s first Shinkansen railway was not the speed of the trains, but that it had been designed from the beginning as an integrated whole.

Disclosure Statement

Felix Schmid is affiliated with The University of Birmingham, an organisation that broadly supports HS2 and is a member of the HS2 Leaders Group. He is the education director of the Birmingham Centre for Railway Research and Education and undertakes research in the areas of railway capacity and sustainability of rail transport.

The University of Birmingham Provides funding as a Founding Partner of The Conversation.

[…] High Speed 1 (HS1), Britain’s first high-speed capable railway […] is modelled on the French Lignes à Grande Vitesse (LGV). This means HS1 has inherited many of its parents’ successful features – and some of their flaws as well.

On the one hand, HS1 supports reliable train operations with a high level of comfort and safety, since the trains and the tracks are well matched. If alignment faults are detected, the ballasted track can be adjusted easily and economically.

On the other hand, frequent maintenance is required to ensure the expected level of performance. Also, while the trains have a high standard of built-in safety, their design slows down both boarding and alighting, and thus results in slower turnaround times and longer “dwells” at stations. The automatic train protection subsystem employed on HS1 is tried and tested, but it compares poorly with newer equipment.

[…] The most obvious challenge is to ensure HS2’s full compliance with the Technical Specifications for Interoperability (TSIs), the standards that will allow high-speed trains from the continent to reach London, Birmingham, Manchester and Leeds.

HS2 must have an operational concept supported by systems engineering of the same quality as that of the Shinkansen network, in terms of train design and infrastructure. The latest Shinkansen trains, the 700A series, are able to decelerate very rapidly, returning energy to the supply line as they do so. Thanks to this level of performance, the infrastructure of the stations and the arrangements between stations can be kept simple and it is possible to exchange a complete junction in one night.

The engineers must choose a type of track that supports the trains’ high level of performance optimally, while offering both low maintenance and very good aerodynamic performance. Most likely, this will be an advanced form of slab-track (a track form that is not supported by ballast but is constructed on a concrete slab). This will have to be complemented by a well-designed formation – that is: cuttings, embankments and tunnel inverts that are strong and stable. Germany has experienced significant problems with recently built sections of high-speed railway slab track because of inadequate compaction of the ground and insufficient drainage.

[…] The many tunnels on HS2 […] must be large enough to limit the resistance to motion of the trains operating at speeds greater than 300 km/h. This presents aerodynamic challenges for both the designers of the trains and the civil engineers.

Segregation of the railway from its environment to minimise external influences on its performance, for instance, by providing platform screen doors in all the stations and aesthetically pleasing security and noise barriers that still allow the passenger a view of the countryside.

In addition to these problems of high-grade engineering, HS2 poses challenges to all local authorities that will be served by new stations. The local transport systems in the regions are generally not of the standard needed to convey the maximum benefit of the high-speed line. The proposed HS2 Manchester Airport station, for example, risks being too far from the heart of the airport and will thus have to be served by an extended tramway. The new East Midlands Hub must offer very good connectivity in all directions – a major challenge for the existing rail network as well as for trams and buses.

[…] It is true that the alignment has been designed for a maximum speed of 400 km/h, necessitating turning radius that is more than 7 km. However, the proposed journey times can be achieved by operating at less than 320 km/h. […] So, while operating HS2 at up to 320 km/h will create a quiet high-speed railway with an acceptable carbon footprint, the capacity for an even faster service will have been built in from the start.

Prof Schmid’s perspective does not consider whether engineering a railway for 320 km/h or 400 km/h is worthwhile in any socio-economic sense. Manchester and London are only 300 kilometres apart, so the time savings from partial running at 400 km/h compared to 250 km/h could not be large. Even running at 300 km/h substantially reduces line capacity and connectivity for intermediate points.

The nearest HS2 gets to serving any town between Manchester and London is the proposed station at Middle Bickenhill. Like the Manchester Airport and Toton stations mentioned by Prof Schmid, the Bickenhill site is very inconveniently located.

HS2 Ltd’s official visualisations of the high speed line are difficult to reconcile with Prof Schmid’s observations. In practice, it’s quite likely HS2 tunnels would feature long and highly visible hood structures at each end, as part of the attempt to reduce noise.

In the view of the Beleben blog, the operating schedule for the Y network is unlikely to be achievable, but that doesn’t mean that Andrew McNaughton and his successors wouldn’t try, if handed enough cash. The attempt might involve constructing platform screens at HS2 stations, and at stations on the classic network served by HS2 trains.

Written by beleben

November 19, 2013 at 12:13 pm

3 Responses

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  1. […] Part one […]

  2. There’s really no reason why the proposed frequencies should not be possible – even if true automatic train operation isn’t available by 2032, which seems highly unlikely, a real-time driver assistance system could provide the extra performance needed just by informing drivers when and how much they should brake and accelerate – this is being looked at by South West Trains to eke a few more paths into Waterloo. Timetable-based systems are already in use to aid time-keeping and reduce fuel consumption, and the relative simplicity of the HS2 network should make such a system relatively easy to implement.


    December 1, 2013 at 3:33 am

    • The reason why the proposed frequencies may not be possible is that no-one has run 14 trains an hour on a system with 400 km/h hour running, or 18 trains an hour on a system with 360 km/h hour running, or 18 trains an hour with 400 km/h running.


      December 1, 2013 at 12:22 pm

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