The big boys have a problem with the pectin left behind by train wheels crushing leaves on the track. It’s always worse on rainy fall days. In years past I’ve seen the P&W’s CT-2 stone train (20-40 loads) with six engines - four on point and two pushing just to make the ruling grade.
When I used to ride RDC’s on the Metro North Danbury line they would often have take two or three attempts to get up a steep grade in the fall.
“With the leaves on the rail, the leaves break down into what looks like a grease. The leaves crush under the wheels — and that literally turns to what has the consistency of grease. Steel wheels on grease don’t work very well, but this aqua train helps keep this under control, keeps our rail system moving. It’s definitely been a great advantage for us.”