The Fourth Severn Crossing - is the barrage the answer?
So far we have three estuarial crossings between South Wales and England.
The oldest is the Severn Tunnel built in 1886 and the two road crossings completed in 1966 and 1996. Another crossing will be required by 2036.
That fourth crossing could be the Severn Barrage renewable energy project of which several options have been put forward.
From a transport point of view the South Wales economy needs additional connectivity from a road and rail crossing whichever scheme is chosen.
The expected increase in passenger demand suggested by the recent Transport Business Case for electric trains, a future High Speed 3 (HS3) service to South Wales and any increase in freight to and from Ireland which might be influenced by a new European Union fixed rail infrastructure facility will not be met by the present tunnel's capacity.
The second Severn Road Crossing was a significant enhancement for the South Wales economy's connectivity, but the rail option was lost due to the considerably higher cost and the funding basis.
The decision then has to be made as to which scheme should be chosen. A comparison can be made of just two of the proposed schemes: the so-called Shoots plan and that of Corlan Hafren. The Shoots scheme would be located near the existing second road crossing and the Severn tunnel. This scheme would fit into the present Great Western main line and require little land-side change in the railway infrastructure connecting South Wales to London, English conurbations and the Channel Tunnel.
A railway across it would relieve any future capacity constraints and would directly serve Cardiff and Newport and west South Wales as at present. It would also directly relieve the existing road crossings especially at peak travel times. As a facility for 200mph high speed trains the Shoots proposal would also be appropriate and as the scheme would, as in France, be built in sections over a period of 40 years.
A crossing designed for high-speed rail operation would also serve conventional trains during the expansion period.
The Shoots scheme would also be welcomed by the ports of Cardiff, Newport and Avonmouth as it lies up-river from the freight routes, cruise operations and the proposed EU motorways of the sea linking the Atlantic seaboard, North Sea and the Mediterranean.
The Corlan Hafren proposal between Lavernock Point, near Penarth, and the Brean peninsula, near Weston-Super-Mare, would take a road and rail connection to a point west of Cardiff.
This would undoubtedly help freight connectivity between West Wales and Ireland and the Channel Tunnel or English destinations.
If HS3 is built along similar principles to the French TGV then a parkway station at a point near Junction 33 or 34 would be ideal to connect with the M4 and the South Wales metro rail service.
On the Bristol side a similar principle would apply with the high-speed station east of Weston-Super-Mare and a further station in mid Wessex between Bath and Swindon.
On the other hand passengers from Cardiff, Newport or Bristol would have to be persuaded to travel west to go east to London. Would their journey time in total be reduced by this high-speed line? In France, the journey time reduction of more than two hours from Avignon to Paris makes a 20-minute journey out to the parkway station worthwhile.
The post-electric train journey time from Cardiff Central to London would be 1h 40m. On a TGV type train via a western parkway it would be 1h 15m. On the Bristol side of the Severn Sea the time advantage would be similar.
The issue facing any train operator therefore would be the percentage of the market between South Wales and London that would make the change. The market distribution and rate of growth in rail usage west of Cardiff would be a major criterion in the evaluation of any new services using the Corlan Hafren barrage crossing. Corlan Hafren claim an energy output 15 times that of Shoots which may provide an income from the barrage sufficient to offer operational and financial incentives to the rail operators.
There are transport benefits from any new crossing including the potential for TGV type high speed trains. The Welsh Government and South Wales business interests have therefore to ensure that a road and rail crossing is built into whichever barrage scheme is constructed.
* Professor Stuart Cole CBE is Emeritus Professor of Transport, Wales Transport Research Centre, at the University of Glamorgan
* An artist's impression of the Corlan Hafren proposal for the severn barrage
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|Publication:||Western Mail (Cardiff, Wales)|
|Date:||Sep 5, 2012|
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