OH Oh...pick me!! Pick me !!! I remember this subject from years back.Superelevation is based on max track speed. In the US...I found some information for 1:1 US railroads that run both freight and passenger trains online and bookmarked it.... Normally, passenger trains run above the balancing speed, and the difference between the balancing superelevation for the speed and curvature and the actual superelevation on the curve is known as unbalanced superelevation. Track superelevation is usually limited to 6 inches (150 mm), and is often lower on routes with slow heavy freight trains in order to reduce wear on the inner rail. Track unbalanced superelevation in the U.S. is restricted to 3 inches (76 mm), though 6 inches (152 mm) is permissible by waiver. There is no hard maximum set for European railways, some of which have curves with over 11 inches (280 mm) of unbalanced superelevation to permit high-speed transportation. The allowed unbalanced superelevation will cause trains to run with normal flange contact. The points of wheel-rail contact are influenced by the tire profile of the wheels. Allowance has to be made for the different speeds of trains. Slower trains will tend to make flange contact with the inner rail on curves, while faster trains will tend to ride outwards and make contact with the outer rail. Either contact causes wear and tear and may lead to derailment if speeds and superelevation are not within the permitted limits. Many high-speed lines do not permit the use of slower freight trains, particularly with heavier axle loads. In some cases, the wear or friction of flange contact on curves is reduced by the use of flange lubrication.