Whenever traffic is controlled by traffic-control signals exhibiting the words "go,""caution" or "stop," or exhibiting different colored lights successively one at a time, or with arrows, the following colors only shall be used and said terms and lights shall indicate and apply to drivers of vehicles and pedestrians as follows:
(a) Green alone or "go":
(1) Vehicular traffic facing the signal, except when prohibited under section two, article twelve of this chapter may proceed straight through or turn right or left unless a sign at such place prohibits either such turn. But vehicular traffic, including vehicles turning right or left, shall yield the right-of-way to other vehicles and to pedestrians lawfully within the intersection or an adjacent crosswalk at the time such signal is exhibited.