SIEMENS

As Brigitte Schäfer leaves her house in Nuremberg, Germany, she thinks about a headline in her morning paper that says, “The world is growing closer together.” While this may be true in a cultural sense, it doesn't change the length of her trip to the office, where she works as a business consultant, or to her meeting in Paris the next day. Today she's taking her car to the office; tomorrow she'll fly to Paris. Still, the mode of transport that would yield the best energy balance for both trips would be a train. That's because Schäfer's drive to work generates three times the CO₂ emissions of a subway ride—and her flight to Paris will produce emissions roughly seven times higher than the same trip by train. Reliability and comfort are very important to Schäfer, however, which is why she has no desire to stand in an overcrowded subway car or wait for a train that's been delayed.

Experts predict that, on a global level, travel will increase by around 1.6 % per year between now and 2030—and that only mass transit systems such as railroads and subways can prevent an equivalent rise in primary energy consumption and CO₂ emissions. One way to make rail travel more dependable and thus more attractive would be to introduce real-time schedules for transit authorities. Siemens Mobility's Falko software, for instance, is a planning and dispatch system that uses optimization algorithms to generate new schedules, adapt them during operation to any disturbance, and implement them in real time.

The software also simulates energy consumption and CO₂ emissions for a variety of routes. What's more, Falko can coordinate the braking and acceleration of different trains on the same line so precisely that the energy fed back into the grid by electric motors during braking can be utilized by other trains for acceleration. This eliminates the need for expensive temporary energy storage units along routes or in trains, resulting in energy savings as high as 25 %. Falko is already in use in 21 local transport systems around the world, and with an industrial rail line for transporting ore in Australia.

“Experience shows, however, that computer-generated processes rarely function optimally when the machines involved are operated by people,” says Horst Ernst, who is responsible for product and portfolio strategy at Siemens Rail Automation. That's why rail driver assistance systems are increasingly taking over the controls. Such systems enable the greatest possible number of trains to run on a single line by optimizing headway distances. They also ensure maximum energy efficiency and punctuality.

One example here is ATO (Automatic Train Operation), which was developed by Siemens and can be integrated into the Trainguard MT control system. With ATO, a train operator only sends out a signal for departure or stopping, and only intervenes in the train's operation in the event of danger. A stored route profile enables the system to calculate how rapidly it should accelerate a train or brake it for curves to ensure that it arrives at the next station on time while using the least amount of energy possible. Tests show that ATO reduces energy consumption by up to 30 % versus human drivers, who tend to brake too sharply and thus have to reaccelerate.

A new standard known as “moving block” operation enables very short headways in conjunction with Trainguard MT. With previous “fixed block” systems, each route was divided into sections delineated by balises—small metal plates equipped with transponders that are placed along tracks. The units register passing trains and then switch signals in the previous section to “stop.” Only after the train has passed over subsequent balises, and the first section is free, can the next train enter that section.

But in moving block operation, balises not only register passing trains but also their speed, which enables the required safe distance between two trains to be calculated much more precisely. The next train on the line therefore doesn't necessarily have to stop, but can instead just be slowed. When used in a subway system, this technology can shorten headways to between 90 and 100 seconds, corresponding to a 50 % increase in the transport capacity of a subway line. Trainguard MT is now deployed in 21 subways around the globe, making it the most widely used train control system. Trainguard MT with ATO is in use in several major Chinese cities, including in the Guangzhou and Beijing subway systems.

Subway riders in Nuremberg are also benefiting from the system. The city's transit authority has operated its U2 and U3 lines fully automatically and without drivers since mid-2008. Trainguard MT allows the company to react very flexibly to an unexpectedly sharp increase in passengers and place additional trains in service in record time, if necessary. The problem of overcrowded trains has thus largely been eliminated (see Pictures of the Future, Spring 2008, Nuremberg's Driverless Subway).

“It's relatively easy to automate a subway line in this manner because all train parameters are known,” says Ernst. “Things are more difficult on long-distance lines, where trains are often joined and decoupled every day.” Because moving block operation requires complete trains with no decoupling of cars along the route, such solutions are therefore only possible at the moment for specific applications involving complete trains, like the high-speed ICE. “Rail system innovation cycles are relatively long,” says Ernst. “Once something's procured, it has to remain in service for 20 or 25 years.”

Good-bye to Locomotive Switching. The European rail system is still waiting for the broad scale introduction of ETCS (European Train Control System). ETCS will eventually replace national control systems for regional and long-distance trains, enabling cross-border travel without having to change locomotives. Siemens has played a key role in defining the system's standards and also supplied equipment for the first regular service ETCS route (Jüterborg-Halle-Leipzig) in 2005. With 50 million operating kilometers through 2009, the company also has the most extensive experience with ETCS technology.

ETCS stores all route data, including grades and maximum permissible speeds. The system continually checks whether a train is traveling on the right route and in the right direction. It also examines whether a train is suitable for its route and is adhering to stipulations such as speed limits through construction sites and in station approaches. ETCS is divided into several levels.

Depending on its configuration, the system ensures adherence to route signals (Level 1), eliminates the need for such signals through continuous transmission (Level 2), and can support moving block operation in the future (Level 3). An ETCS-equipped train could thus travel from Nuremberg directly to Athens, Greece, without switching locomotives, something hardly possible these days due to the very different national control systems still in use. The system would therefore significantly reduce travel times.

Europe is still a long way from full transition to ETCS, however, with initial widespread implementation not expected until 2014. Nevertheless, ETCS technology is already helping to make train connections safer, more reliable, and in some cases more energy efficient. Spain's Velaro train, for example, uses ETCS technology from Siemens to cover the roughly 650 km from Madrid to Barcelona in under three hours. In China, new high-speed trains equipped with ETCS technology have an on-time performance of 98 %.

Such figures make trains more attractive to new customers. Brigitte Schäfer, for her part, has decided on the spur of the moment to take a train to Paris because she needs to prepare for her meeting—and that can be done more comfortably in a train than in a cramped plane, not to mention a car.