You're forgetting about all of the additional computer equipment, as well as the additional substations required, to extend traditional BART to Antioch. When BART is talking about the cost per mile, they're talking about more than just the r.o.w. and track. You also have to include the additional power needed (i.e. substations), third rail, and trackside computer equipment. Eliminating those three items alone saved millions of dollars. Do some research.