Every time energy prices jump, railroads will go back and update their electrification studies. There would be an advantage if the railroads electrified the high density mains between the Los Angeles basin to Bakersfield and Barstow/Yermo. In both cases, you would have to get BNSF and UP to agree how to split costs. As pointed out, there is an advantage of using regenerative braking to put power back into the grid instead of throwing it away as heat. (I wonder if anyone every calculated how much heat is added to the atmosphere by heat/friction created by braking various vehicles? Global Warming?) There are certain operating advantages of electric locomotives compared to diesel-electric.

Now for the down side. Mainline electric road locomotives have pretty much been custom designs, and are much more expensive than diesel-electrics. Electric locos still have to be maintained, so I would guess they might actually cost the same or more than a comparable diesel-electric. You also have to create an entire cantenary system and pay for the electrical supply to it. Raw copper prices are $3+ per pound. I was recently quoted around $6 per foot for 2/0 insulated locomotive cable, which probably 1/4 to a 1/3 of the copper used for modern cantenary. True, the supply cabling would be aluminum and the carrier wires would be galvanized steel - but they aren't giving any of that away these days either. And don't forget that the signal system has to be compatible with the propulsion power using the rails as the return ground, not to mention the "noise". And once the train gets to the end of electrified territory or a track, now you have to change engines. (My idea is to put a small diesel on the engines to allow them to enter yards or secondary tracks that do not have overhead, but something else to maintain.) Add all these costs together, and the costs, even split between BNSF, UP and some commuter agencies would be many multiples of billions of dollars for even this limited territory.

Now assuming that the government printed money for grants or just plain outlawed the diesel locos in the basin, now you have to deal with the electric power supply itself. Urban California is out of water and power, far outstripping the supply within its borders. You would have to obtain a reliable and cost effective supply of electricity (1.21 gigawatts?) on a long term contract. When the grid fails due to an electrical shortage, the railroads would be cut off in favor of people's needs. A 4400 hp diesel-electric needs around 3,150 kw each under full load, so figure 100 locos under 1/2 load on average would be 157,500 kw or 15.75 megawatts and if they were lucky might regenerate 1/4-1/3 of that. (I think I got the math right?) And the current administration has a war on any fossil fuel power plants, so where would that much power come from. It would obviously be generated outside California and require new transmission lines to be built.

And all of this would take a completely new infastructure, which would require creating its own "pollution" to create. The railroads won't electrify the LA Basin or any other substantial territory for the simple reason it would bankrupt them. I do think the government will eventually force electrification in the name of the environment.

Now anyone care to consider the amount of pollution being created by millions of commuters in urban areas in their personal automobiles (regardless how clean) versus a mass transit system - or the emissions per passenger mile for airlines?