Rocking trains

While I was reading about the Shinkansen on the internet  few days ago, some links led me to the wiki article about the Pendolino tilting train developed by FIAT of Italy. The Pendolino gets its name from Pendolo - Italian for pendulum and the suffix ino as in bambino or topolino.

The Pendolino design has since been evaluated by multiple train operators in many countries including RENFE of Spain, Cisalpina of Switzerland, PKP of Poland, Ceske Drahy of the Czech Republic and Virgin Trains of the UK. Spanish CAF (translated: Construction & Auxiliary of Railways) and Bombardier transportation of Canada have developed their own tilting trains as has the engineering team that builds the Shinkansen.

There are essentially three different approaches that engineers have taken to get the train to tilt as it goes into a corner. The Pendolino uses hydraulic actuators to push up one side of the car while the bogie remains flat with respect to the rail. The Spanish Talgo Pendular adopts a passive suspension and the Shinkansen uses airbags that inflate to raise the side on the outside of the curve.

All of these approaches were attempts at trying to achieve higher speeds on regular, i.e. Non HSR tracks.

I was under the impression that tilting trains helped the train travel faster along the same curve than a non tilting train without the risk of derailment. Not true. The only way to get trains to travel faster around a curve is to bank the track, i.e. raise the outside rail so that the bogie is inclined into the curve. Clearly, you can only go so far with raising one of the two rails without running the risk of a slower travelling train tipping over. In Japan, an early warning system against earthquakes on the Shinkansen brings the train to a complete halt in case tremors are detected and you definitely wouldn't want to stop on a part of the track where the incline is 45 degrees.

The trains tilt not to travel faster around a banked track but to make the travel more comfortable for travellers. For some strange reason, humans wearing formal clothes prefer to be pushed into their seats as against being pushed into the armrest, and tilting the train achieves this objective. In denim jeans and T-shirts, the same humans want to feel the G Forces laterally, transversely and longitudinally. We want to rock. It is for those times that we have roller coasters.