Surely the maximum cant would be more influenced by damage on the inner rail inflicted by heavy freights moving very slowly around the curve, which is always possible no matter how fast the passenger trains can go.
My concern is the extra weight of tilt-equipped rolling stock and the effect that has had on acceleration, as demonstrated by Voyagers, and fuel consumption and wheel/rail wear maintenance. More modern active bogie and suspension designs could eliminate much of the additional weight of traditional tilting, and improve the ride and reduce lateral sway of car bodies. Proponents of this new technology claim major savings in rail and wheel wear are possible with active steering and roll compensation incorporated in a much more compact and lighter bogie. It is interesting that both Bombardier and Hitachi have experience in this modern form of 'mechatronic' active suspension and these firms are collaborating on a joint HS2 bid.
In an ideal world, cant would be set so that all trains would pass at the same speed. However, in the real world we have a mixed traffic railway and compromises must be made. Track must be set to allow for all speeds from zero up to the maximum required. This may involve reducing the maximum speed, accepting enhanced wear or straightening the track. My original suggestion was that cant had been increased with the increase in freight traffic speed. Any extra wear would be noticed for slow freights but if you can keep them running at their maximum speed by regulation there should be a lower level of wear to the inner rail.
I can well believe that, as in the early days of tilt on the 221s I believe there were a fair number of unexpected brake appliications & failures resulting from tilt system faults , regardless of whether they were actually running on tilt or non tilt routes, however that appears to have been largely fixed nowadays on the remaining Virgin Voyagers, happy to be corrected if wrong
