It will be interesting to see what kind of truck the new BART car has. Rail-wheel interaction has a lot to do with the truck design. The original BART truck was designed by Gustav B. Sundby of LFM Atchison (Rockwell Mfg. during BART era). As I understand, before LFM, Gus worked on the EMD Flexicoil family for locomotive application. Budd and others had been working on lightweight, inside-bearing truck designs for passenger and transit equipment in the late 50s and into the 60s. A number of these were tried on the various lab cars at the BARTD Concord test track in the 60s. For more details on the Sundby designs, see US patents 3,646,893 (key ingredients of BART truck) and US 3,313,245 for earlier instantiations with the novel pivoted transom. FPO and other on-line sites like that of the USPTO can be searched to find these and prior art.