At first, you believe safety depends on making the driver know you are there.
So you knock louder. You explain more clearly. You hope the person holding the power will recognize your position and act carefully.
Then another possibility appears:
You can move.
The position you occupy is not necessarily the position you must remain in. Agency is not controlling the vehicle, the driver, or the traffic. Sometimes it is remembering that you still have a body, a voice, and a way out from underneath what frightens you.
Move when the opening appears.