The following empty cars are susceptiple to stringlining: propane tank cars, pig flats, auto parts cars, bulkhead flats, 35 ton cars at the right place, etc. Many cars are in the 65 to 80 foot range. More important is curvature, weight of cars and amperage draw.

A good engineer knows where all of his train is- in relation to curves, valleys, and crests. That gets really difficult to visualize beyond 8,500 feet. Even harder to control is what all that slack is doing two miles or more back. Now try and control all of that two miles back and also set up the power for the up-coming crest and valley, then into a permanent speed resriction. How will the DP respond to all of this?

It's the usual deal: Get more bang for your buck! That may be fine in manufacturing, but probably less so with public safety. How big should the largest jet airplane be? How big should a semi-tractor be?