A couple of things have happened. One is that over the last 20 years, to keep freight rates down and keep them going down, we have increased the weight per car. Just in the last five years the weight per freight car has gone up from 263,000 pounds to 284,000 pounds as the new standard. That's almost 35 tons per axle. The European trains are typically 20 to 22 tons, the Russian up to 25 tons. So we're way up there in getting heavy loads on our infrastructure.
One of our problems with this is that although we can change out the rail as it wears and put in a little heavier rail, we have bridges that are 75 or 100 years old. They're well designed, for sure, with lots of room for additional weights and additional loads, but there are something like 3,000 steel railway bridges on each of CN and CP across Canada. If you have to change just one percent of those every year, that's 30 bridges a year, just to do one percent. So there's a constant drain on availability of capital for these kinds of infrastructure upgrades.