Train speed optimization, also known as Zuglaufoptimierung, is a system that reduces the need for trains to brake and accelerate, resulting in smoother and more efficient operation.
A train is a form of rail transport consisting of a series of connected vehicles that generally run along a railroad track to transport cargo or passengers. The word "train" comes from the Old French trahiner, derived from the Latin trahere meaning "to pull" or "to draw".
While train speed optimization needs some technical infrastructure, it is more of an operational concept than a technical installation. One can relatively easily implement train speed optimization using for instance cab signalling (e.g. using ETCS), but the presence of a cab signalling system does not necessarily mean that it uses train speed optimization. Train speed optimization may also be implemented using conventional signalling.
Cab signaling is a railway safety system that communicates track status and condition information to the cab, crew compartment or driver's compartment of a locomotive, railcar or multiple unit. The information is continually updated giving an easy to read display to the train driver or engine driver.
Railway signalling is a system used to direct railway traffic and keep trains clear of each other at all times. Trains move on fixed rails, making them uniquely susceptible to collision. This susceptibility is exacerbated by the enormous weight and inertia of a train, which makes it difficult to quickly stop when encountering an obstacle. In the UK, the Regulation of Railways Act 1889 introduced a series of requirements on matters such as the implementation of interlocked block signalling and other safety measures as a direct result of the Armagh rail disaster in that year.
Conventional signal operation
Usually, trains are allowed to run at the maximum speed the track allows until the distant signal of next occupied block. This is inefficient in many cases, because this way the train comes to a halt in front of the red signal and has to accelerate again from zero.
Advantages using train speed optimization
If the train slows down much earlier, it reaches, given the right timing, the distant signal just when the home signal switches to green. This way, the train does not need to stop. Thus, wear on the brakes is reduced and the train uses less energy. But the main reason, especially for trains that accelerate slowly, is that the train passes the home signal at high speed, compared to the conventional case where the train often has to accelerate from standstill. This effectively increases track capacity, because the time it takes for the train to run from the distant signal (that has just turned green) to the home signal is often much less than the time it takes for a train to accelerate from the home signal.
Equipment
For a train speed optimization system to work, it is necessary to have a signalling system which is capable of displaying several different speeds, for instance 40, 60, 90 km/h and the full line speed, which also requires a train protection system that is able to handle these cases (cab signalling may replace these installations). Further, the track must be equipped with inductive loops that detect the presence of trains with sufficient precision (or other means of detecting the positions of the trains). Finally a computer system is needed that is able to reasonably predict the movements of the trains for the next few minutes.
A train protection system is a railway technical installation to ensure safe operation in the event of human failure.
Train speed optimization in practice
The expensive and complicated installations usually only make sense for heavily used routes.
Lenzburg is a town in the central region of the Swiss canton Aargau and is the capital of the Lenzburg District. The town, founded in the Middle Ages, lies in the Seetal valley, about 3 kilometres south of the Aare river. Lenzburg and the neighbouring municipalities of Niederlenz and Staufen have grown together in an agglomeration.
Killwangen is a municipality in the district of Baden in the canton of Aargau in Switzerland.
Altstetten is a quarter in district 9 of the city of Zürich in Switzerland. It was formerly a municipality in its own right, but was incorporated into Zürich in 1934.
On trains, the expression emergency brake has several meanings:
The Train Protection & Warning System (TPWS) is a train protection system used throughout the two UK passenger main-line railway networks, and in Victoria, Australia.
Automatic train control (ATC) is a general class of train protection systems for railways that involves a speed control mechanism in response to external inputs. For example, a system could effect an emergency brake application if the driver does not react to a signal at danger. ATC systems tend to integrate various cab signalling technologies and they use more granular deceleration patterns in lieu of the rigid stops encountered with the older automatic train stop technology. ATC can also be used with automatic train operation (ATO) and is usually considered to be the safety-critical part of the system.
A track circuit is a simple electrical device used to detect the presence or absence of a train on rail tracks, used to inform signallers and control relevant signals.
Linienzugbeeinflussung is a cab signalling and train protection system used on selected German and Austrian railway lines as well as the AVE in Spain. The system was mandatory where trains were allowed to exceed speeds of 160 km/h (99 mph) in Germany and 200 km/h (120 mph) in Spain. It was also used on some slower lines to increase capacity. The German Linienzugbeeinflussung translates to continuous train control, literally: linear train influencing. It is also called linienförmige Zugbeeinflussung.
PZB or Indusi is an intermittent cab signalling system and train protection system used in Germany, Austria, Slovenia, Croatia, Romania, Israel, on two lines in Hungary, and on one line in Canada and the United Kingdom.
The railway signalling system used across the majority of the United Kingdom rail network uses lineside signals to control the movement of trains.
Transmission Voie-Machine is a form of in-cab signalling originally deployed in France and used on high-speed railway lines. TVM-300 was the first version, followed by TVM-430.
Railway signals in Germany are regulated by the Eisenbahn-Signalordnung. There are several signalling systems in use, including the traditional H/V (Hauptsignal/Vorsignal) system.
Sistema di Controllo della Marcia del Treno (SCMT) is a discontinuous train Cab signalling system used in Italy. It shares many features with the Ripetizione Segnali (RS) system, the two systems co-existing and working together. The main purpose of SCMT is to control the respect of the speed limit imposed by the signal aspect and the line condition.
The current French railway signalling system is in force on the Réseau Ferré de France since 1930, when the code Verlant was applied.
Japanese railway signals, according to the ministerial decree defining technical standards of railways, are defined as indicating operational conditions for railway staff driving trains.
Pulse code cab signaling is a form of cab signaling technology developed in the United States by the Union Switch and Signal corporation for the Pennsylvania Railroad in the 1920s. The 4-aspect system widely adopted by the PRR and its successor railroads has become the dominant railroad cab signaling system in North America with versions of the technology also being adopted in Europe and rapid transit systems. In its home territory on former PRR successor Conrail owned lines and on railroads operating under the NORAC Rulebook it is known simply as Cab Signaling System or CSS.
Swiss railway signalling describes the railway signalling systems used in Switzerland by the different railway companies. There are two main types of signal, used up to 160 km/h, above which speed cab signalling is required.
The Italian railway signalling currently in use, employed on the Italian national railway network, is regulated by the "Regulation on signals", issued by the Italian railway infrastructure manager, RFI.
The application of railway signals on a rail layout is determined by various factors, principally the location of points of potential conflict, as well as the speed and frequency of trains and the movements they require to make.
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