Originally Posted by
nfmisso
If you go to the heaviest of land based transport systems (freight railroads), you will find "Dynamic Brakes"; which use the traction motors as generators dumping electrical power into resistor grids (toaster wires), generating MegaWatts of heat and drag. Why do railroads use this technology - overall it is cheaper than totally relying on friction brakes.
On a typical diesel-electric locomotive, they already have the traction motors there for power anyway, plus they aren't concerned about weight- I understand they have to add weight in the frame to get the traction they need- so altogether totally different from bicycle needs.