Well, the first question to answer is ... what is the definition of a High Speed train? Obviously, it is any train which travels fast. However, for the purposes of this article it can be considered any speed over (125 mph) 200 kph. In the UK, trains are limited to a maximum of (125 mph.) 200 kph. even though many of the engines, especially the new ones now arriving, are capable of reaching (140mph.) 224 kph. and have been known to do so on the West Coast Main Line (WCML). The last stop southwards from Scotland and the North West is Warrington. From there, the trains run non-stop to London Euston. On the stretch of line from Crewe to Rugby, trains have been known to make up for any accumulated lost time by running over 200 kph. and, therefore, are able to arrive at Euston on time. The timetable gives 1hr.45 mins. for the 182 miles from Warrington to Euston. That means an average of 167 kph. Obviously that means phases that are at lower speeds for part of the route, so some are higher, as I previously indicated.
Apart from the track itself, the limiting factor in High Speed is visual. Lineside signals of whatever sort cannot be relied upon at high speeds. Since the train passes them so fast, the humans cannot be relied upon to see them clearly and interpret the signals correctly. That means that all the information has to be given inside the driver's cab. The lineside information will still be given as before for those trains that use the line but do not travel at high speeds and are not adapted. The high speed trains will use information provided by visual display as well as sound when necessary. This conversion is already being made on some lines.
The ability to achieve high speeds obviously comes at a cost. The straightening of the tracks on present lines makes for higher speeds on all lines. The elimination of bottlenecks is a necessity on many lines as the bottlenecks mean low speed limits. Crossing junctions and changing from one line to another can also reduce speeds unless improvements have already been introduced. In most cases, even these improvements still mean a reduction in speed from the highest available on the line. It can, therefore, be seen that investing large amounts of money in improvements in the infrastructure is not worthwhile if there is no noticeable gain in speeds. So I cannot see lines being improved from 224 kph to just 240 kph.(max). The increase, therefore, has to be greater to make it worthwhile.
Another factor to be taken into account is the cost of running at high speeds. It is well known that the higher the speed, the greater the exponential (not linear) use of electricity to achieve the high speed. That being the case, all the high speed lines, in Europe at least, do not run at 400 kph.(250 mph.) or above. They run at about 320 kph.(200 mph.)
There is also another reason not to run trains at 400 kph. The stopping distance for a train at 320 kph. is up to 10 kilometres. In an emergency that could probably be shortened but would be extremely uncomfortable for the passengers. Also, the maximum braking level that can be applied would probably make the trains run the risk of derailment. This means that the higher the speed, the greater the distance between trains is needed for safe operation. Higher speeds thus mean lower capacity (fewer trains) on the line. That would make any increase in speed self-defeating. Let us assume then that the chosen working speed for HS2 and any other new or updated line is 320 kph.(max.).
To achieve something approaching the maximum speed means that turning corners is limited to gentle bends in the track. The radius of the curved track can be no more than 7 kilometres if one wants to try to maintain something like the maximum speed. That means if the track has to turn to avoid an obstacle, like a hill or mountain, some major infrastructure or even a population centre then the whole trajectory of the track has to be well-thought-out. In an island like Great Britain, there are many population centres in a relatively small area. In fact, the vast majority of the populace lives in England where about 53.3 million plus people live compacted together with relatively little separating them.That means you cannot build HS tracks in swathes in England as you can in France or Spain, because they have the room to do it.
With regard to "population centres in a relatively small area", in this island there is one destination with a large population, which was decided upon by our Victorian predecessors, that "all railways lead to London". This was a recognition of the Roman idea that "all roads lead to Rome". Everywhere else became secondary or so the central thinkers believed. With regard to High Speed rail lines this led to two ways of thinking.......(a) The HS lines were to be built from end to end i.e. London to Edinburgh, .. to Glasgow, .. to Manchester, .. to Leeds, .. to Cardiff, .. to Bristol, .. to Birmingham and so on. This was an adaptation of the way HS lines were being built in Spain and France. In these places the stops were built outside the intermediate cities, meaning the travelling public had to make its way to (or from) a stop in the middle of nowhere necessitating the need of a car when buses were not available. This is not in the spirit of the goal of use of carbon fuels, just making us more reliant on the car, meaning a higher use of carbon fuels.
The second way of thinking ..... (b) was based on the idea that passengers would want to be picked up at a place convenient for them and their use of public transport, to a destination we wanted to get to/ from where we can continue and terminate our journey in a convenient manner on public transport. This is a feather in the cap of the Victorian planners because over the years, destinations have been built together with public transport systems that have been built to satisfy the needs of travelling passengers. Therefore, since it is there use it.
The effect on the construction of any HS line means that the trains will take a little longer to leave the station until the line becomes high speed. The arrival time will also be delayed by a little amount. However, the benefit is that any delays will not be excessive while we are maximising the renovation and use of the original lines and stations in/into the cities. The money saved will be substantial.
Before we progress, we should mention inclines. In the past many rail lines were built up mountain ranges with steep gradients. At first the steam engines had to struggle to take several coaches or freight wagons up the heights. This ability improved with the application of engines with greater horsepower. However, the aim was to make the existing infrastructure more efficient. Now our aim is to take advantage of our attained knowledge so as to reduce the need for deviations on the routes, and the capricious routing dictated to us by nimby landlords.
Looking
at the line from Lancaster to Penrith, on reaching Morecambe Bay the
line runs at sea level next to the water for a good length. Sea levels
rising with the change of climatic conditions and the expectancy of more
frequent and more violent storms on stretches open to the sea would
make it prudent and foresighted to start elevating the railway on to a
viaduct to run behind the houses and not spoil their view of the Bay.
This would run to at least Carnforth. The difficulty of incorporating
the new fast line into the WCML so as to run through both Carnforth and
Oxenholme would suggest that the new two tracks would not run through
those stations, but near them(and most probably not providing an HS station at those two points).
From Oxenholme onwards the new fast two tracks would be planned towards Penrith more directly by elevating the line on to a viaduct as far as possible until a tunnel is essential. I calculate that at most such a tunnel towards Penrith would be between 10 and 12 kms. long (at an estimated maximum altitude of 300 metres). The whole stretch from Lancaster to Penrith could be reduced by the two new fast tracks from the existing 82.5 kms. to 75.5 kms. The saving in length would be thus 7 kilometres. (quote taken from my blog,"The Crewe to Manchester fast railway link, and the WCML." 6 June 2023).
I have looked at the HS2 line again from Oxenholme to Penrith. In order for it not to enter the Lake District National Park I have redrawn the line (it appears in orange on the picture of the map), ensuring it is totally outside the Park as given to me on Google Earth. The realignment has a length of 26kms. compared to my original offering which has a length of 28.4kms. So by accepting the updated version we save an additional 2.4kms. of new line construction. In addition to that my original version envisaged a tunnel at 300 metres of 10-12 kms. to cross the highest points. The new version tunnel needed to cross the highest points, would most likely be about 8kms. in length at an estimated height of 320 metres. Two short sections in the open air would be within those 8kms. so the actual tunnelling would be less (about 7km.).
Thus, it can be seen that there are ways of constructing HS viaducts as well as tunnels to solve the problems of straightening the lines. We will not construct completely straight lines for the tracks, but on the whole they will tend to have long bends and permit higher speeds than at present. Another point that should be emphasised is that I see all the trunk routes, such as the WCML and ECML, as having four tracks at least. This is to ensure that there are two tracks for high speed trains plus two for freight and stopping trains. The differing types of traffic are thus separated, and the route is thus assured of alternative tracks in case of need, such as an accident or necessary maintenance.They do not necessarily have to be constructed together. That is a preference but not essential. A very clear example of that is my proposal for HS2 from Newcastle to Edinburgh. This new line would venture further inland, past Coldstream, while the ECML would remain along the coast, through Berwick and Dunbar. The HS line to Edinburgh would have to curve towards Edinburgh so that it does not impinge on The Northumberland National Park. Similarly the HS2 from Carlisle to Glasgow could be straighter than the WCML, to complement it.
(HS2 Dark blue line: Gretna Green to Glasgow HS3? light blue line: Newcastle to Edinburgh WCML & ECML white lines: Carlisle to Glasgow and Newcastle to Edinburgh)
One last thing we have to consider is if there are going to be fast stopping trains along the HS corridors. They mustn´t stop every, say, two miles as some would want but we might find it useful to the local populations to provide one or two stopping points(and passing lines) between the last important town and the destination. This is done already on the HS1 between London St. Pancras and Ashford in Kent (before the trains branch off on to local commuter lines). After all it is logical to drum up custom when/where the capacity exists, as well as being economically beneficial.
The next step is to commit to these modifications and, furthermore, put them into effect. This might be done at a moderate steady pace but before one realises it 3hours for the journey from London to Glasgow and Edinburgh can come into one´s grasp.
