§ 1116. Lane direction control indications. Whenever traffic is controlled by lane direction control signals located over the individual lanes of a highway, only the colors green, yellow and red shall be used, and said signals shall indicate and apply as follows: (a) Traffic facing a steady downward pointing green arrow signal may travel in any lane over which such signal is located. (b) Traffic facing a steady yellow X signal is thereby warned that the related green downward arrow indication is being terminated and that a red X indication will be exhibited immediately thereafter and such traffic shall vacate, in a safe manner, the lane over which such signal is located. (c) Traffic facing a flashing yellow X signal may travel in any lane over which such signal is shown preparatory to making a left turn, using proper caution. (d) Traffic facing a steady red X signal shall not enter or travel in any lane over which such signal is located.