Why Amtrak trains will stay slower
+ an important conclusion
Looking at the last 10 pages, it's now time for a summary, which curve speeds might be achievable under the operating conditions in the USA.
Unless there is a modernization of regulations, operation at an cant deficiency of
11.8 inches cannot be expected in the USA, because the necessary low axleload, and the heavyweight
carbodies for the FRA regulations are not compatible.
A realistic expectation, for dedicated passenger railroad track of high standard, might be 9 or 10 inches.
- Track maintenance by freight operators is no precision work. On mixed usage freight railroads, substraction of another two inches should be expected. This would mean a maximum of 7 or 8 inches.
- While the allowed superelevation in the USA is 6 inches, freight railroads use much less on mountain routes. More than 3 inches of physical superelevation shouldn't be expected, maybe 4 inches in some special cases.
For a translation into practical implications, the following table gives examples of speed results for a given radius. Passenger priority track and freight track is compared to the maximum, that is currently allowed in Europe: