Why would a train have an unloaded car between two heavily loaded sections?
Doesn’t that risk derailment if the train makes an emergency stop?
I would think that the risk of the light car lifting would prevent them from having it there. What am I missing?
Those cars are likely there as spacers, so as to not stress structures (ie, bridges) along the line.
Such movements often have specific requirements that need to be met.
Car is a 65 foot flat car with a empty weight of 65500 pounds. Actually I am surprised there isn’t a spacer car between the locomotives and the load on the depressed center four truck car that is hauling the high wide and HEAVY load. The car seems to be QTTX 130605 which has a tare weight of 160000 pounds and a load limit of 366000 pounds and a maximum allowed weight on rails of 526000 pounds.
Clearance restrictions for oversized and/or overweight loads will frequently require nominally empty spacer cars - Windmill blades are an example of a long load that requires more the one car for their tranportation.
When spacer cars are mentioned, the bottle train operated by PRR/PC/CR/NS over the years to the steel mill in Riverdale (also various owners) has always had one or two spacers between each bottle car, which also has 20 or 24 wheels to spread the weight.
When Beth Steel at Sparrow Point was still in operation they would ship out poducts of a length that required a spacer car on either end to accomidate the overhangs.
It depends on a lot of things.
Curvature, grade, car and adjacent car geometry, slack condition before emergency, where in train emergency was initiated…
Movements of high, wide, and really heavy loads are not common, and already have restrictions. As such, empty buffer cars, etc, are not the problem that a mix of loads and empties in a conventional manifest train are.