49 CFR § 399.207 - Truck and truck-tractor access requirements.
(a) General rule. Any person entering or exiting the cab or accessing the rear portion of a high profile COE truck or truck-tractor shall be afforded sufficient steps and handholds, and/or deck plates to allow the user to have at least 3 limbs in contact with the truck or truck-tractor at any time. This rule applies to intermediate positions as well as transition between intermediate positions. To allow for changes in climbing sequence, the step design shall include, as a minimum, one intermediate step of sufficient size to accommodate two feet. Exception. If air and electrical connections necessary to couple or uncouple a truck-tractor from a trailer are accessible from the ground, no step, handholds or deck plates are required to permit access to the rear of the cab.
(b) Performance requirements. All high profile COE trucks or truck-tractors shall be equipped on each side of the vehicle where a seat is located, with a sufficient number of steps and handholds to conform with the requirements of paragraph (a) of this section and shall meet the performance requirements:
(1) Vertical height. All measurements of vertical height shall be made from ground level with the vehicle at unladen weight.
(2) Distance between steps. The distance between steps, up to and including the door sill step, shall provide any person a stable resting position which can be sustained without body motion and by exerting no more arm force than 35 percent of the person's body weight per grasp during all stages of entry and exit. This criterion applies to intermediate positions as well as transition between intermediate positions above ground level.
(i) When the ground provides the person foot support during entry or is the final step in the sequence during exit, and the step is 508 millimeters (20 inches) or more above ground, the stable resting position shall be achievable by the person using both hands to grasp the handhold(s) and requiring no more arm force than 35 percent of body weight per grasp.
(ii) The vertical height of the first step shall be no more than 609 millimeters (24 inches) from ground level.
(3) Construction. Each step or deck plate shall be of a slip resistant design which minimizes the accumulation of foreign material. Wherever practicable, a self-cleaning material should be used.
(4) Foot accommodation. Step depth or clearance and step width necessary to accommodate a climbing person are defined by using a minimum 127 millimeter (5 inch) diameter disc as shown in Illustration III.
(i) Single foot accommodation. The disc shall fit on a tread rung, or in a step recess, with no exterior overhang.
(ii) Two-foot accommodation. Two discs shall fit on a tread rung, or in a step recess, with no exterior overhang.
The 127 millimeter (5 inch) disc is only intended to test for a minimum depth and width requirement. The step need not retain the disc at rest.
(5) Step strength. Each step must withstand a vertical static load of at least 204 kilograms (450 pounds) uniformly distributed over any 127 millimeter (5 inch) increment of step width.
(7) Exterior mounting specifications for handholds. Each handhold, affixed to the exterior of the vehicle, shall have at least 38 millimeters (1.5 inches) clearance between the handhold and the surface to which it is mounted for the distance between its mounting points.
(9) Handhold strength. Each handhold shall withstand a horizontal static load of at least 114 kilograms (250 pounds) uniformly distributed over the area of a hand print and applied away from the mounting surface.
(11) Deck plate strength. Each deck plate shall be capable of withstanding the vertical static load of at least 205 kilograms (450 pounds) uniformly distributed over a 127 millimeter (5 inch) diameter disc.