You have to wait because a rail-crossing barrier is lowered. How can you now help protect the environment at this point?

Using the automatic start-stop system helps protect the environment when waiting at a lowered rail-crossing barrier because it turns off the engine automatically when the vehicle is stationary. This reduces fuel consumption and emissions since the engine is not idling unnecessarily. Simply putting the vehicle in first gear or activating the parking brake does not reduce fuel use or emissions; these actions are more related to safety and vehicle control. Therefore, using the start-stop system is the environmentally friendly choice in this situation.