NS GP60s

[silicon212]

This is true, but in the case of Magma, the trip from Magma into Phoenix is mostly on a downgrade (Phoenix is 1100' above sea level, Magma is over 2000 feet ASL), and the territory going west is mostly flat - so the Magma turn had gravity on their side with the acid loads.  Generally, acid loads totaled somewhere around 2-6 cars per train, while the BP trains have considerably more.