Actually, when we updated our track safety rules, this is why we made track geometry testing as well as rail flaw detection mandatory, to measure exactly what you're talking about. Depending on the tonnage being used on a track, there are different levels of inspection they have to carry out. That gives us the level to know that the track is up to date. If it's not, they have to fix it.
On June 12th, 2014. See this statement in context.