I wonder if anyone has taken the wheel loading weight of the B40-8s into account. Those units have the highest wheel loading of any unit out there, because they are quite heavy (even heavier than some older 6-axles) and spread the weight to the rail through 8 wheels instead of 12. I have come across plenty of folks at the shortlines who have no idea that a 4-axle can be worse on track than a 6-axle locomotive. All 4-axles are not the same, to say the least. If you're dealing with tight gauge, the 4-axle is the answer, but if you're dealing with light rail or less than ideal track conditions, a heavy loading like the B40-8s introduce is bad news.
Mike Derrick