Originally Posted by
Macchi30
But I thought that since this train is able to tilt on the rail, that it can actually sustain higher speeds for longer periods of time
There are three ways to handle curves at high speed...
1. Veeeery shallow curve, so you hardly feel the G's. Problem here is you have to move buildings, roads, mountains, lakes, etc out of the way in order to lay the track along the desired route.
2. Banked curve, but the bank only works at the speed it was intended for, too slow or two fast and it's uncomfortable for pax and at some point the train will tip over. I don't think a stationary or very slow train could sit upright on a tight curve banked for 200 mph, pretty sure it would tip over. That's a problem if you have to slow or stop unexpectedly.
3. Wheel system that locks onto the rails, like a roller coaster. But this adds cost and complexity to both the wheels and rails, and would very uncomfortable for pax. They'd be in four-point harnesses and the ride would resemble, well a roller coaster. You could in theory combine this with a cabin which swivels to the appropriate back angle to curve (like a plane in coordinated flight) to eliminate side forces for the pax, but you'd still get every bit of the G's in the down direction. A tight curve at speed would be too many G's for pax safety.