High Speed Railway vehicle Capacity

High Speed Rail is the new railway vehicle. Around the world, proposals for new high speed lines are booming. Many existing railway systems are experiencing ever increasing passenger and freight traffic and some routes are showing signs of stress, such as poor punctuality and overcrowding, often due to the capacity constraints of their systems. This is leading to calls in various countries for new high speed routes to be built to provide more railway capacity, with the added benefits of reduction in the pollution and congestion caused by cars on the roads and planes in the skies. These are laudable objectives but a big question is just how much capacity can a high speed rail route provide? Lots of numbers have been cast about in the hope of making a case for various high speed rail projects but not many of them are accurate and some are simply unrealistic. In this paper I look at the question of high speed railway capacity, with the case of the British HS2 project as an example and analyse the factors affecting capacity, including terminals, junctions, stations and rolling stock performance. High Cost Transport Railways are high investment systems. In the UK, a new double track railway, like HS2, will cost around £76million per km. (HS2, 2011). A modern train will use up to £1.5million per vehicle. Signalling systems will be up to £3million/km. Power supplies and communications will fall into similar price ranges. These systems represent a significant investment and this investment must be seen to be used to its fullest potential. For this reason, a railway and its systems must be planned and engineered to allow the maximum capacity to be realised, if not at opening, then for a future date. In this paper, I examine the issues surrounding the potential capacity that might be achieved on a high speed railway. Line Capacity First, what is meant by railway capacity? Railway capacity can be described in a number of ways but, in this paper, I use the term “line capacity” as the ability of a railway to carry a certain number of trains in one direction on one track over a certain period. It is determined by how many trains you can run on a track in this direction in an hour and is expressed as trains per hour (tph). It can also be described as “headway” - the time interval between successive trains. I offer a formal definition of headway as, “For a single direction, the elapsed time at a given point between the passing of the front of one train and the passing of the front of the next.” Line capacity will depend on train performance, particularly braking and acceleration, length and how trains are controlled. How many trains can be run will also depend on the infrastructure – the power available, the maximum line speed, the station spacing, the terminal design, gradients and the railway control (signalling) systems. On top of that, the operating conditions - dwell times at stations, terminal operations, allowances for speed restrictions and recovery margins will also affect throughput. Although we are looking at high speed lines, these conditions apply to all railways, regardless of the top speed of the fastest train. Looking at capacity for existing high speed routes, we can see published ranges of between 12 and 15 trains per hour. The UK’s HS2 is proposing an eventual total of 18 tph. This is at least a 20% increase over the established norms. Could this be done? If so, how? What factors have to be considered? In this paper, I examine the major issues