2009 California Vehicle Code - Section 21400-21401 :: Article 2. Official Traffic Control Devices

21400.  The Department of Transportation shall, after consultation
with local agencies and public hearings, adopt rules and regulations
prescribing uniform standards and specifications for all official
traffic control devices placed pursuant to this code, including, but
not limited to, stop signs, yield right-of-way signs, speed
restriction signs, railroad warning approach signs, street name
signs, lines and markings on the roadway, and stock crossing signs
placed pursuant to Section 21364.
   The Department of Transportation shall, after notice and public
hearing, determine and publicize the specifications for uniform types
of warning signs, lights, and devices to be placed upon a highway by
any person engaged in performing work which interferes with or
endangers the safe movement of traffic upon that highway.
   Only those signs, lights, and devices as are provided for in this
section shall be placed upon a highway to warn traffic of work which
is being performed on the highway.
   Any control devices or markings installed upon traffic barriers on
or after January 1, 1984, shall conform to the uniform standards and
specifications required by this section.

21401.  (a) Except as provided in Section 21374, only those official
traffic control devices that conform to the uniform standards and
specifications promulgated by the Department of Transportation shall
be placed upon a street or highway.
   (b) Any traffic signal controller that is newly installed or
upgraded by the Department of Transportation shall be of a standard
traffic signal communication protocol capable of two-way
communications. A local authority may follow this requirement.
   (c) In recognition of the state and local interests served by the
action made optional for a local authority in subdivision (b), the
Legislature encourages local agencies to continue taking the action
formerly mandated by this section. However nothing in this
subdivision may be construed to impose any liability on a local
agency that does not continue to take the formerly mandated action.