Passengers struggling with oversize luggage on escalators is a problem, and not just at airports; I have witnessed several incidents on the London Underground where passengers have lost their grip on large suitcases. Escalators are simply not designed to safely carry large suitcases on wheels, and the consequences of an accident are potentially very serious. Rather than imposing arbitrary limits on the size of luggage that can be safely taken on escalators - and dealing with the ensuing arguments - it seems sensible to limit it to hand luggage only.