westr wrote:With well cars, longer containers don't necessarily have to be on top; I have seen 40-foot containers on top of longer containers. However, some older well cars can only accomodate a 40-foot or 48-foot container on the bottom, requiring that 48-foot or 53-foot containers be on top. Newer well cars are built to accomodate 53-foot containers on the bottom.
A slight correction to this post (that I just realized is two years old!): 40' well cars aren't necessarily older and 53' wells aren't necessarily newer. They're built to serve two distinct markets, those being the international market (dominated by 20', 40' and 45' equipment) and the domestic market (now almost exclusively 53' equipment). Overall, the NA 53' fleet is newer, but only because the 53' container is, itself, pretty new. Sure, (most) 53' wells can carry 20'/40' boxes, which makes them more versatile as a 40' ART well car can't carry 53' boxes even on the top deck. However, the roads often try to segregate their international and domestic business... and they really frown on putting a 40' in a 53' as it's highly inefficient from a train-length perspective.
By the way, David Benton... we use the same term (twistlocks) for IBCs in the US... must be a universal term.