I referred to SMART as heavy rail on another site and was corrected (rightly). If you are British you are correct, but in US usage SMART is not heavy rail. It has nothing to do with being FRA compliant. BART is heavy rail, although it may pain you to hear it.

Here is the APTA definition:

"Heavy Rail is a mode of transit service (also called metro, subway, rapid transit, or rapid rail) operating on an electric railway with the capacity for a heavy volume of traffic. It is characterized by high speed and rapid acceleration passenger rail cars operating singly or in multi-car trains on fixed rails; separate rights-of-way from which all other vehicular and foot traffic are excluded; sophisticated signaling, and high platform loading."