Upon all roadways a vehicle shall be driven upon the right half of the roadway, except as follows:
(a) When overtaking and passing another vehicle proceeding in the same direction under the rules covering such movement.
(b) When placing a vehicle in a lawful position for, and when the vehicle is lawfully making a left turn.
(c) When the right half of the roadway is closed to traffic.
(d) Upon a roadway designated. and sign posted for one-way traffic.
(e) When the roadway is not of sufficient width.