In addition to any codified vehicle safety requirements, what other safety equipment may be required on a special permit move? The following items may be required on a vehicle or vehicle combination making a move under special permit:

(1) Brakes.

(a) Braking equipment must comply with the performance and maintenance requirements of RCW 46.37.360, unless specifically stated on the special permit.

(b) A special permit will not be issued to a vehicle "in tow" of another vehicle without brakes unless a three-axle truck or truck-tractor with a minimum unladen weight of fifteen thousand pounds is employed as the power unit. The power unit must also have sufficient power and brakes to control the towed unit at all times.

(2) Drawbar—Towline.

(a) The drawbar or other connection between vehicles in combination must be of sufficient strength to hold the weight of the towed vehicle on any grade where operated.

(b) No trailing unit shall whip, weave, or oscillate or fail to follow substantially in the course of the towing vehicle.

(3) Flags.

(a) Flags must be displayed on all four corners of all overwidth loads, and at the extreme ends of all protrusions, projections, or overhangs as required by RCW 46.37.140. During hours of darkness, lights as required by RCW 46.37.140 shall be located at each point where flags are required.

(b) When the distance between the towed vehicle and the towing vehicle exceeds fifteen feet, a white flag or cloth not less than eighteen inches square must be fastened at the approximate middle of the span.

(4) Lights. Vehicles, whether factory direct or custom built, used in the transport of extra-legal loads must be equipped with brake lights and turn signals as required by RCW 46.37.200.

(5) Two-way communications. When pilot/escort vehicle(s) are required, the transport vehicle must be equipped with a two-way radio communications system capable of providing reliable two-way voice communications at all times between the operators of the pilot/escort vehicle(s) and the transport vehicle.

(6) Rear-view mirrors.

(a) Rear-view mirrors must be mounted in compliance with RCW 46.37.400.

(b) Pilot/escort vehicles may be used in lieu of the two hundred-foot rear sight/distance requirement in RCW 46.37.400.

(7) Safety chains and devices.

(a) A load being moved by special permit must be securely fastened and protected by safety chains or other load securing devices pursuant to Code of Federal Regulation, 49 C.F.R. Part 393.100.

(b) Dragging of the load on the highway shall not be permitted.

(c) A vehicle with a boom or other aerial device attached must have the boom or device secured in such a manner that it cannot elevate (ratchet up) or sway during transport.

(8) Signs.

(a) Warning signs displaying "OVERSIZE LOAD" shall be mounted in the front and rear of the transporting vehicle where the lights and license plate(s) are not blocked and the sign is visible from the front and rear of the transport vehicle.

(b) Signs are to be displayed only during transit of an over dimensional load and must be removed or retracted at all other times.

(c) An "OVERSIZE LOAD" sign must be at least seven feet wide and eighteen inches high with black lettering at least ten inches high in with a brush stroke between 1.4 and 1.5 inches on yellow background.