Oh, most new track is designed for operation speeds far beyond what's commercially expected: it's very cheap to do (the primary requirement, after all, is about

Oh, most new track is designed for operation speeds far beyond what's commercially expected: it's very cheap to do (the primary requirement, after all, is about curve radius, which just affects your choice of route). The signalling, the overhead line equipment, the rolling-stock… all of that is all designed for the initial operational speed, because that does become expensive (or non-existent) if you want to push the speed up.