A bus is stopped at a railroad crossing with a green traffic signal. What is the Maryland manual's listed approach for that type of exception?

1. A full stop is not required, but the driver must slow down and carefully check for other vehicles and trains
2. The bus may cross without slowing or checking
3. The driver must still stop between 15 and 50 feet in every green-signal case
4. The driver should shift gears on the crossing to match the signal