[wsh]

As I understand it, the Southern Pacific was concerned less with avoiding competition for its Peninsula Commute service than with ensuring that it wouldn’t ever be required to take over BART and bear its operating losses. This was long before Amtrak or the 4R Act, and railroads were still under strict economic regulation by the ICC and CPUC, so the prospect of being ordered to take over a money-losing passenger operation was a real concern.

That’s also the actual reason, or so the story goes, for BART’s non-standard 5′6″ (1676 mm) track gauge: the physical impossibility of interchange with SP’s lines was one more assurance that the SP wouldn’t be entangled with BART or its costs.