California Code, Vehicle Code - VEH § 21373

The governing board of any school district may request the appropriate city, county, city and county or state agency to install traffic control devices in accordance with the warrants established pursuant to Section 21372.  Within 90 days thereafter, the city, county, city and county or state agency involved shall undertake an engineering and traffic survey to determine whether the requested crossing protection meets the warrants established pursuant to Section 21372.  The city, county, city and county, or state agency involved may require the requesting school district to pay an amount not to exceed 50 percent of the cost of the survey.  If it is determined that such requested protection is warranted, it shall be installed by the city, county, city and county or state agency involved.