§ 1682. Local traffic-control devices. Local authorities in their
respective jurisdiction shall place and maintain such traffic-control
devices, conforming to the state manual and specifications, as they may
deem necessary to indicate and carry out the provisions of this chapter
or local traffic ordinances, orders, rules or regulations or to
regulate, warn, or guide traffic, except that a city having a population
in excess of one million shall conform to the state manual and
specifications only insofar as such local authority in its discretion
deems practicable.