Kimiaki Sasaki

Carbody tilting – technologies and benefits

Carbody tilting is today a mature and inexpensive technology allowing higher speeds in curves and thus reduced travel time. The technology is accepted by many train operators. Today more than 5000 tilting vehicles, defined as tilting carbodies, have been produced world-wide by different suppliers. Tilting trains can be divided into naturally tilted trains and actively tilted trains. However, also natural tilting will often include actuation to ensure satisfactory dynamic performance. The mechanical solutions for tilting involving pendulums or rollers are well proven. They have also become compact enough to avoid passenger area intrusion. The proportion of the lateral acceleration compensated by tilt has decreased over the years. In the early days of tilting train development, it was often assumed that the compensation should be 100%. Compensation of 50–70% are typically used in todays actively tilting trains, while natural tilting ones still retain compensation close to 100%. Recent developments in control have provided the market with more clever systems erasing the former problem with time delays. The result is beneficial for both ride comfort and low risk of motion sickness. As an example, running time simulations on the Swedish mainline Stockholm–Gothenburg have shown that the running time benefit for a tilting train vs. a non-tilting train, both with a top speed 275 km/h, is about 10%.