SMART is already largely irrelevant due to its design and routing limitations.

IMHO 79mph relates better to rural areas and dates better to maybe mid-20th Century California with like one quarter of the people and automobiles.

SMART's heavy FRA freight albatross renders it impossible to add grade separations like flyovers and its diesel propulsion makes it impossible for subway, necessary to reach the magnet destination of the City.

The SMART ROW is 19th century, which brings up the prima facie concept of "speed greater than is reasonable and prudent under the circumstances, conditions and actual and potential hazards then existing." Those crossing gates can be easily smashed thru as the box truck wreck demonstrates. Where can you drive a car legally at 66mph or 77 mph except on a grade separated highway?

Consider ebart, sister doodlebug op to SMART: all grade separated and top speed of 75mph. Or think 66mph or 77mph as typical speeds of Imperial BART. Can you picture BART 10 cattlecar trains doing grade crossings?