Cal. Code Regs. tit. 8, § 7021 – Haulage Vehicle Operation Procedure.

(a) When operating vehicles, consideration shall be given to the condition of the roadway, weather, curves, grades and mechanical condition of the vehicle.
The vehicle shall not be operated at a speed which will endanger the driver or traffic.
On curves, the vehicle speed shall be limited so that it can be stopped within one-half the visible distance of the roadway.
(b) (9-23) (9-24) Haulage vehicles shall at all time be operated under positive control. When descending grades, the vehicle shall be kept in gear.
(c) (9-5) Where other warning signals are not provided, the vehicle's warning device shall be sounded before moving the haulage vehicle.
(d) (9-45) The loaded haulage vehicle shall not be moved away from the shovel or loader until the load is balanced and trimmed.
(e) Haulage vehicles shall not be driven unnecessarily while the body is in the dump position.
(f) No workman shall be permitted under the raised body of a haulage vehicle until such body is secured in its raised position.
(g) The hands or feet shall not be used to guide a hoist or winch cable on a haulage vehicle. When necessary to control a moving cable, the drum and sheaves shall be equipped with a device that will guide the cable to its proper position without being handled, or the employee shall be provided with a device which will enable him to guide the cable safely.
(h) (9-12) Cabs of mobile equipment shall be kept free of extraneous materials.
(i) (9-45) Equipment which is to be hauled shall be loaded and protected so as to prevent sliding or spillage.
(j) (9-58) If truck spotters are used, they shall be well in the clear while trucks are backing into dumping position and dumping; lights shall be used at night to direct trucks.
(k) (9-68) Lights, flares, or other warning devices shall be posted when parked equipment creates a hazard to vehicular traffic.