You Must Be This Tall to Ride
There are no seat belts or air bags on the MTC buses, let alone convertible seats like some newer cars feature. It's worse on light rail, where the brief stopping times wouldn't allow the time necessary to properly seat such children even if the train seats had such accommodations.
No, the risk is too great, and it falls disproportionately on the poor who must use public transit. Post signs that say "you must be this tall to ride the Hiawatha line."