SF and BART...

http://switchingmodes.com/proposals/bart-capacity-tbt

http://fc01.deviantart.net/fs24/f/2009/237/2/5/San_Francisco_streetcar_map_by_qweqwe321.png

https://www.flickr.com/photos/walkingsf/5069356670/in/set-72157622518181915 ,
https://www.flickr.com/photos/walkingsf/4948162685/in/set-72157622518181915

http://burritojustice.com/page/3/?archives-list=1 1961

https://www.flickr.com/photos/walkingsf/sets/72157622518181915/page2 1956

Mt. D. BART test track
https://www.flickr.com/photos/walkingsf/5430314884/in/set-72157622518181915,
http://trid.trb.org/view.aspx?id=11953

https://www.google.ca/search?q=2nd+bart+tunnel+plans&es_sm=93&tbm=isch&tbo=u&source=univ&sa=X&ei=5ib4U6eIGuroigLC1YH4Bg&ved=0CB4QsAQ&biw=1422&bih=776&dpr=0.9

http://www.counterweights.ca/2014/08/the-troubled-usa-today-%E2%80%94-august-for-the-people-in-the-bay-area-waiting-for-river-falcon-at-walnut-creek/