Two longs, a short, and a long is the standard born sequence for trains approaching road crossings, and has been so for a century.
Engineers who skip the sequence for ANY road crossings do so at their peril and possible disciplinary action.
(Note: there are some exceptions to this rule airhorized by the feds for special road crossings in urban areas with safety gares protecting all possible ways to enter the rr right of way. And stil, collisions between trains and vehicles or pedestrians occur on a seemingly daily basis.