California Code of Regulations
Title 8 - Industrial Relations
Division 1 - Department of Industrial Relations
Chapter 4 - Division of Industrial Safety
Subchapter 7 - General Industry Safety Orders
Group 2 - Safe Practices and Personal Protection
Article 7 - Miscellaneous Safe Practices
Section 3333 - Blue Stop Signs, Blue Flags and Blue Lights

(a) The employer shall provide blue stop signs (signs) or blue flags for use by day, and in addition, blue lights for use if night work is necessary, and cause them to be displayed before employees are permitted to work in, upon, or under any standing railroad car or cars under conditions where unanticipated movement or disturbance of such car or cars might endanger employees or equipment.

EXCEPTION: Railroad cars on portions of industrial tracks served by common carrier railroad corporations shall be provided with protective signs and lights as required by the operating railroad's rules filed with the Public Utilities Commission pursuant to their General Order 108.

(b) The cars shall be adequately secured by positive mechanical brakes, blocking or chocking of wheels or other means that will prevent their movement. Blocks or chocks shall be stored out of the track area when not in use.

(c) Required signs, blue flags, and blue lights shall be placed on the track at a height of 3 to 5 feet and not less than 10 feet from either or both ends of the cars as necessary to afford protection and in such position as to provide a clear and unobstructed view of the signs, flags and lights from any approaching railroad equipment.

(d) Required signs, blue flags, and blue lights shall be placed and removed by one of the employees working in and about the car. This employee shall be selected, instructed and directed by the employer in the safe procedures involved in placing and removing the signs, flags and lights.

(e) Blue stop signs shall be of substantial material not less than 12 inches by 15 inches in size and shall bear the word "STOP" in letters not less than 4 inches in height. Other words may be placed thereon in letters not less than 2 inches in height. The letters shall be white on a blue background.

(f) Signs, blue flags and blue lights shall be mounted suitably for proper display.

(g) Signs, blue flags and blue lights shall be maintained so as to assure effective display and shall be available to enable compliance with this order.