The Highway Department shall install and maintain traffic control
devices when and as required under the provisions of this chapter,
to make effective the provisions of this chapter, and may install
and maintain such additional traffic control devices as it may deem
necessary to regulate, warn or guide traffic under the Vehicle and
Traffic Law of the State of New York, subject to the provisions of
§ 1682 and § 1684 of that law, and in accordance
with the Manual of Uniform Traffic Control Devices as published by
New York State.