These would be 1100 metres long a considerable increase on the current 800 metre maximum length for Freightliner trains from the Southampton area. Thus the Dibden Bay trains present the immediate challenge of extreme length as well as weight plus an identified need to carry 9’6” high containers. In detail, the SRA (in their Ten Year Plan) and Railtrack have previously identified the core route for these trains as being via Southampton Central. The latter has, it is understood, been superseded by an alternative to Reading and Acton to Willesden.
The potential operator (Freightliners Ltd) is adamant that the trains will use the above route via Oxford as it offers the lowest potential operating costs and best resource utilisation for them. This route is also consistent with SRA strategy for the development of high loading gauge core freight routes and the evolution of the Thames Valley Cherwell Valley route as a ‘3 freight trains per hour freight route from the south to the Midlands and North. The potential to route these trains via the Southampton Bath route in its entirety is very heavily constrained by a number of features on the route but even more so by those beyond it. In essence these trains could use the route, or parts of it, in several different ways.
The most radical would be to use the route throughout and this must be regarded as extremely difficult without massive investment. The reasons for this are that, Capable website designers apart from constraints south of Bath (below) the trains then have to pass through the Bristol area going either via Bristol Parkway thence. Cheltenham and the Barnt Green route to Birmingham or taking the Severn Tunnel and then the North & West Line from Newport to Shrewsbury. In either case the train will have to be regulated (in Loop lines) through the Bristol area across the path of lines used by frequent passenger train services.
There are no loop lines capable of accommodating trains this long anywhere between Bath and Bristol and no room to build such loops without land purchase and major civil engineering works. It would be possible to build loops, or additional running lines, on the gradient out of Bristol towards the South Wales Main Line. (also used to access the Barnt Green route) and it would then be possible to use an existing long loop just east of the Severn Tunnel on the route heading west and then north.