1.  INTRODUCTION

  RPC Wales is concerned that Wales-England rail services are increasingly constrained by the Severn Tunnel and considers that now is the time for a serious look at how additional capacity should be provided for the long term.

  This non-technical paper is intended to identify four options, to introduce issues to be considered as part of the assessment of each option and to promote further consideration of the proposals by and further debate with the relevant authorities.

  These authorities include:

—  the Welsh Affairs Committee;

—  the Welsh Assembly Government;

—  the South West Regional Assembly;

—  the Strategic Rail Authority;

—  Network Rail.

  No effort is made to estimate one crucial issue: cost. This would have to be an integral part of the next stage of assessment of these four and any other identified options.

2.  BACKGROUND

  The Severn Tunnel is four miles and 629 yards long and links the English and Welsh sections of the Paddington-South Wales main line.

  Construction began in early-1873 and, after enormous difficulties which included two major floods from "the Great Spring", was opened to passengers on 1 December 1886. In conjunction with the "Badminton Line" between Patchway and Wootton Basset Junctions, it shortened the original London—Swansea route via Gloucester by 47 miles. It was then the longest non-London Underground rail tunnel in Britain and the longest underwater tunnel in the world.

  Its benefits include:

—  twin track throughout;

—  reasonably graded approaches, (1/90 climb into Wales and 1/100 climb into England);

—  electrified pumping stations, (and water sold for industrial use);

—  every day, about 130 passenger trains and 80 freight trains passing through.

  The tunnel, however, is not trouble free; constraints include:

—  risk of flooding;

—  long signalling sections which restrict train paths;

—  confined drainage tunnels and shafts, hard to access and maintain;

—  75mph speed restriction;

—  W8 freight gauge;

—  inadequate alternative routes when closed for maintenance and renewal;

—  no headroom for electrification.

  Much work was essential in the tunnel in the late 1990's and the maintenance engineers gained some notoriety for closing the tunnel frequently and at short notice, causing serious delays to and disruption of regular services. Some of this work followed the numerous recommendations of the public inquiries in Bristol and Cardiff in 1992 into the collision between two trains within the tunnel on 7 December 1991, recommendations arguably made more numerous by the uncertainty as to the precise cause of the accident. Safety provisions were enhanced with considerable difficulty and expense.

  In the last couple of years however, apart from a couple of serious and avoidable clashes with major sporting occasions at the new Millennium Stadium in Cardiff, the tunnel's reliability and availability is greatly improved, with a significant reduction in unplanned closures.

  Nevertheless, taking all aspects of service performance into account, RPC.W considers the Severn Tunnel to be a significant constraint on existing rail services. More fundamentally and seriously, RPC Wales considers the tunnel will be unable to cope with the planned and anticipated increases in rail traffic along this vital route.

  Better use of the Severn Tunnel can certainly be achieved by improvements within and near the tunnel, eg:

—  safely reduce intervals between trains by installing addition signals within the tunnel which reduce the length of signalling sections—planned for years but still not implemented;

—  raise the line-speed through the tunnel to 90 or 100mph;

—  remove single lead junctions near Filton Junction, especially on the route to Bristol—promised for 2004;

—  additional platforms at Filton Abbey Wood Station so stopping trains do not obstruct through trains—promised for 2004;

—  reinstate two more tracks (to total four) between Filton Junction and Bristol Temple Meads, so trains to/from South Wales do not obstruct trains to/from Bristol Parkway Station and beyond to the North and East—no known plans.

  As they are implemented, these projects will progressively enhance capacity through the approaches to the Severn Tunnel and therefore through the tunnel itself. It is however estimated that traffic growth will still exceed this additional capacity sooner rather than later; say, well within 10 years.

  Within that period it is assumed that the following national schemes will be complete:

—  WCML PUG 1 and 2 (at last);

—  ECML bottle-neck removals;

—  CTRL Section two, from Fawkham Jct. to London Kings Cross;

  and that the Great Western Renewal will be making rapid strides in a westerly direction.

  Meanwhile, the Severn Tunnel will become a more and more severe constraint on all services, especially on the key South Wales-Bristol and London services for which, unlike South West England and Bristol-London services, there is no effective alternative route.

  Recognising that the right option to provide additional capacity between England and Wales will be a major project with lengthy lead time, probably over ten years to successful completion, RPC.W consider work should begin now to consider the options and to identify the preferred solution.

  RPC.W reaffirms its suggestion that the options considered should include:

—  the Second Severn Road Crossing;

—  a dedicated rail bridge;

—  a new rail tunnel;

—  the Severn tidal barrage.

3.  THE FOUR OPTIONS

  Each option is now outlined in a little more detail.

3.1  The Second Severn Road Crossing

  Road and rail have shared bridges over rivers and estuaries for years, especially in developing countries with limited resources and rugged terrain, eg Canada, India, NZ and Australia.

  Examples in Britain are few, apparently because of a lack of strategic thinking, but perhaps also due to inter-agency indifference. The few working examples in Wales include the Britannia Bridge (as re-built) between Bangor and Holyhead and the Briwet Bridge on the Cambrian Coast near Penrhyndeudraeth.

  Modern bridges however commonly have full provisions for both rail and road, eg Denmark-Sweden, Hong Kong Airport, etc. Such bridges are conceived, designed and built for this shared purpose.

  Although not designed and built to include rail, the Second Severn Road Crossing, (SSRC) may hold potential for rail use. Merits include:

—  its alignment, which is very close to that of the rail tunnel beneath, (indeed, great care had to be taken during bridge construction to control foundation works straddling the tunnel);

—  its arrangement of long multi-span approach viaducts and short central span;

—  the modern road freight loads for which the bridge is designed may well be comparable with the loads of modern medium-paced light-weight rail cars suitable for Bristol-Newport-Cardiff shuttle services;

  The revised and additional loadings would certainly require significant alteration and strengthening of the crossing, just as almost every other road bridge has experienced as traffic intensities and permitted lorry loadings have increased since the bridges were first designed. It is considered that the design and construction techniques to modify the SSRC suitably are already available.

  Rail connections to the existing network would be short on both Severn banks, and track grades and curvatures throughout should not be operationally onerous at all.

3.2  A Dedicated Rail Bridge

  The original high-level rail bridge was completed in 1879 between Sharpness and Lydney but was badly damaged by a ship in 1960 and never re-opened before demolition. Its alignment is reasonably favourable for reconstruction on the West bank, but its Eastern approaches are unsuitable for direct and speedy access to either Bristol, to the GW mainline at Westerleigh Junction or to the Gloucester-Stroud route to Swindon.

  The preferred option for a dedicated rail bridge would therefore be a new bridge on a new alignment.

  The first choice option that the SSRC be a joint-rail crossing (by design) having been lost, the rail bridge alignment now has considerable freedom. Preferred alignment is likely to be somewhere in a band between a mile upstream and five miles downstream of the Severn Tunnel.

  Opportunities exist of enhancing existing network connections by aligning the bridge with existing rail-lines, eg:

—  to Avonmouth, making it attractive for Bristol and freight traffic, but less directly attractive for London trains, except by releasing capacity in the original tunnel;

—  to Hallen Marsh Junction on the Severn Beach line from Bristol Parkway, making it attractive for high speed trains straight through Filton Junction.

  On any alignment it would be prudent to design foundations and superstructure capable of accommodating a future road deck, perhaps particularly for an Avonmouth alignment.

3.3  A New Rail Tunnel

  Thanks to the excellent experience already gained on the Channel Tunnel Rail Link to London, the levels of tunnelling expertise in the UK have soared and the costs have plummetted. Certainly the Severn geology and hydro-geology will always be more complex and challenging than English chalks and clays, but a new rail tunnel may well be the quickest, easiest and most cost-effective way of enhancing English-Welsh rail links.

  In principle, the alignment of a new rail tunnel has the same flexibility as a new rail bridge.

  In practice it will be more restricted by the geology and a bored tunnel in stable rock may therefore be impractical as far downstream as Avonmouth.

  Estuary bed conditions may, however, favour an immersed tube similar to, but much longer than, the A55 under the Conway estuary on the North Wales Coast.

  A new bored tunnel alongside the existing provides the additional and valuable opportunity to up-grade the old Severn Tunnel to modern standards of safety and services by cross-connections throughout their length, including:

—  passenger escape routes in the event of emergency;

—  controlled bi-directional ventilation;

—  modern drainage and lighting.

  The pair of tunnels in close parallel would offer greatly increased flexibility of operation and maintenance as well as increased capacity, with segregation by speed and power generally leading to passenger trains normally using the modern tunnel and the original tunnel restricted to freight traffic.

  A new tunnel some distance from the old would not have many of these benefits.

  Any modern tunnel should be sized to accommodate future electrification with UK standard overhead lines.

  Modern train power units probably mean the new tunnel approaches could be steeper than present, hence reducing the tunnel length and cost. However, fuel costs would rise and/or train speeds would fall as a consequence, albeit for only a short section of their overall journeys.

3.4  The Severn Tidal Barrage

  The Severn Tidal Barrage to harness the enormous energy of the rising and falling tides in the estuary was first proposed in the 19th Century—a contemporary engraving shows a train crossing it!

  It is considered that in time and due to:

—  continuing growth in UK electricity demand and of our economic and social reliance on it;

—  the pollution from and relative inefficiencies of coal, oil and gas energy sources;

—  the increasing political and technical risks of imported fuels and energy;

—  the relative unpredictability and unreliability of many renewable energy sources, especially wind;

—  increasing success in identifying the environmental impacts of large projects and of managing them acceptably;

  active interest in the potential of tidal power in general and of the Severn Estuary in particular will revive sooner rather than later.

  Sites for the barrage have been investigated on many alignments between as far upstream as Aust Cliff-Beachley Point (almost exactly under the First Severn Road Crossing) and as far downstream as Porlock (West Somerset)-Nash Point (Glamorgan). Most proposals have concentrated on the an alignment between Weston-super-Mare-Lavernock Head near Penarth.

  Wherever sited and whenever built, it too provides an opportunity for rail and road crossings.

  Current estimates suggest the barrage would be such a large project, and because it would not be available as a transport link until virtually complete, it will almost certainly not be available within the period necessary to supplement the Severn Rail Tunnel. Nevertheless, it is a project which could clearly contribute to cross-Severn transport links, and its development should be positively monitored.

  Rail access for construction purposes on both shores should be aligned with permanent use in mind.

4.  CONCLUSIONS

  At this preliminary stage RPC Wales concludes:

—  the Severn Rail Tunnel is old and difficult and expensive to maintain;

—  its alignment for train services between London and South West England and South Wales is most suitable for modern transport needs;

—  its usage is on the practical limits of capacity, and enhancements available cannot keep ahead of the growth in demand in the mid- and long-term;

    and that:

—  additional and alternative capacity must be provided on this strategic route.

  Therefore, the options, including the four outlined in this Note, should be assessed, budgeted, ranked and considered in further detail until the single all-round best-value option is identified for further detailed assessment.

5.  RECOMMENDATIONS

  This Note is issued to the Welsh Affairs Committee as supplementary evidence to its recent Inquiry into The Provision of Rail Services.

  It is also issued to:

—  the Welsh Assembly Government;

—  the Strategic Rail Authority;

—  Network Rail;

—  the Welsh Transport Forum;

—  the South West Regional Assembly;

—  Rail Passengers' Committee for Western England;

—  London Transport Users' Committee;

  also to all other interested parties, including all Train Operating Companies using the Severn Tunnel; with an invitation to all to comment on, help to improve and to adopt and promote.

The Second Severn Rail Crossing

  From time-to-time, RPC.W should review, revise and re-issue this Note to include additional facts, issues and options that emerge and that RPC.W considers strengthen the case to be considered for the Second Severn Rail Crossing.

6.  APPENDICES

6.1  Location Plan of Severn Crossings

  To be developed for the next issue.

6.2  References

  1.  Channel Tunnel Rail Link Section 1 Proceedings of the Institution of Civil Engineers, Vol 156, Nov 2003

  2.  The Oxford Companion to British Railway History; edited by Jack Simmons and Gordon Biddle, 1997.

  3.  The Great Western Railway, A New History; by Frank Booker, 1977.

  4.  Railways: Civil Engineering; by Bryan Morgan, 1973.

  5.  Hidden Dangers—Railway Safety in the Era of Privatisation, by Stanley Hall, 1999.

  6.  The Severn Tunnel—Its Construction and Difficulties 1872-87, by Thomas A Walker, 1888.

6.3  Acknowledgements

  To colleagues in the industry and on RPC Wales for their advice and encouragement; however all errors remain those of the author.

Owen P Williams
Chartered Civil Engineer

Clive G Williams
Secretary

December 2003