When two passenger or freight trains approach a crossing at the same time, the train on the road first built shall have precedence if the tracks are both main tracks over which all passengers and freights on the road are transported. If only one track is such main track, and the other is a side or depot track, the train on the main track shall take precedence. If one of the trains is a passenger train and the other a freight train, the passenger train shall take precedence, and regular trains on time take precedence over trains of the same grade not on time. Engines with the cars attached, not on time, shall take precedence over engines without cars attached, not on time.