Each engine centers on a regenerative braking system that can recover up to 5MW of energy, much of which goes back to the power grid. The machinery is smarter, too: it can self-diagnose problems and mitigate the impact until repairs are possible. Commuters won't immediately notice the difference when ACS-64 trains reach the rails between this fall and 2016, but there should be important behind-the-scenes savings.With a simple enough locomotive, sufficient instrumentation, and a competent engineer, you can cut out the misbehaving circuits and roll on. Regeneration is a simple flick of a switch.
Contemporary control circuitry, with a.c. transmission and thyristors, achieves results that the traction pioneers could only dream about.
You put all that technology over fewer wheels and less unsprung weight.
On the other hand, that Bi-Polar is more distinctive than the beefed-up Class 87 profile of Amtrak's latest power.