Appendix F to Part 238 - Alternative Dynamic Performance Requirements for Front End Structures of Cab Cars and MU Locomotives

Appendix F to Part 238 - Alternative Dynamic Performance Requirements for Front End Structures of Cab Cars and MU Locomotives

As specified in § 238.209(b), the forward end of a cab car or an MU locomotive may comply with the requirements of this appendix in lieu of the requirements of either § 238.211 (Collision posts) or § 238.213 (Corner posts), or both. The requirements of this appendix are intended to be equivalent to the requirements of those sections and allow for the application of dynamic performance criteria to cab cars and MU locomotives as an alternative to the requirements of those sections. The alternative dynamic performance requirements are applicable to all cab cars and MU locomotives, and may in particular be helpful for evaluating the compliance of cab cars and MU locomotives with shaped-noses or crash energy management designs, or both. In any case, the end structure must be designed to protect the occupied volume for its full height, from the underframe to the anti-telescoping plate (if used) or roof rails.

The requirements of this appendix are provided only as alternatives to the requirements of §§ 238.211 and 238.213, not in addition to the requirements of those sections. Cab cars and MU locomotives are not required to comply with both the requirements of those sections and the requirements of this appendix, together.

Although the requirements of this appendix are stated in terms applicable to Tier I passenger equipment, they are also applicable to Tier III passenger trainsets under § 238.711. Specifically, the cab ends of Tier III trainsets shall comply with the requirements of this appendix to demonstrate the integrity of the end structure.

Alternative Requirements for Collision Posts

(a)

(1) In lieu of meeting the requirements of § 238.211, the front end frame acting together with its supporting car body structure shall be capable of absorbing a minimum of 135,000 foot-pounds of energy (0.18 megajoule) prior to or during structural deformation by withstanding a frontal impact with a rigid object in accordance with all of the requirements set forth in paragraphs (a)(2) through (a)(4) of this appendix:

(2)

(i) The striking surface of the object shall be centered at a height of 30 inches above the top of the underframe;

(ii) The striking surface of the object shall have a width of no more than 36 inches and a diameter of no more than 48 inches;

(iii) The center of the striking surface shall be offset by 19 inches laterally from the center of the cab car or MU locomotive, and on the weaker side of the end frame if the end frame's strength is not symmetrical; and

(iv) Only the striking surface of the object interacts with the end frame structure.

(3) As a result of the impact, there shall be no more than 10 inches of longitudinal, permanent deformation into the occupied volume. There shall also be no complete separation of the post, its connection to the underframe, its connection to either the roof structure or the anti-telescoping plate (if used), or of its supporting car body structure. (A graphical description of the frontal impact is provided in Figure 1 to this appendix.)

(4) The nominal weights of the object and the cab car or MU locomotive, as ballasted, and the speed of the object may be adjusted to impart the minimum of 135,000 foot-pounds of energy (0.18 megajoule) to be absorbed (Ea), in accordance with the following formula:

E_a = E₀−E_f

Where:

E₀ = Energy of initially moving object at impact = 1⁄2 m₁*V₀².

E_f = Energy after impact = 1⁄2 (m₁ + m₂)*V_f².

V₀ = Speed of initially moving object at impact.

V_f = Speed of both objects after collision = m₁*V₀/(m₁ + m₂).

m₁ = Mass of initially moving object.

m₂ = Mass of initially standing object.

(Figure 1 shows as an example a cab car or an MU locomotive having a weight of 100,000 pounds and the impact object having a weight of 14,000 pounds, so that a minimum speed of 18.2 mph would satisfy the collision-energy requirement.)

Alternative Requirements for Corner Posts

(b)

(1) In lieu of meeting the requirements of § 238.213, the front end frame acting together with its supporting car body structure shall be capable of absorbing a minimum of 120,000 foot-pounds of energy (0.16 megajoule) prior to or during structural deformation by withstanding a frontal impact with a rigid object in accordance with all of the requirements set forth in paragraphs (b)(2) through (b)(4) of this appendix:

(2)

(i) The striking surface of the object shall be centered at a height of 30 inches above the top of the underframe;

(ii) The striking surface of the object shall have a width of no more than 36 inches and a diameter of no more than 48 inches;

(iii) The center of the striking surface shall be aligned with the outboard edge of the cab car or MU locomotive, and on the weaker side of the end frame if the end frame's strength is not symmetrical; and

(iv) Only the striking surface of the object interacts with the end frame structure.

(3)

(i) Except as provided in paragraph (b)(3)(ii) of this appendix, as a result of the impact, there shall be no more than 10 inches of longitudinal, permanent deformation into the occupied volume. There shall also be no complete separation of the post, its connection to the underframe, its connection to either the roof structure or the anti-telescoping plate (if used), or of its supporting car body structure. (A graphical description of the frontal impact is provided in Figure 2 to this appendix.); and

(ii) After FRA review and approval of a plan, including acceptance criteria, to evaluate compliance with this paragraph (b), cab cars and MU locomotives utilizing low-level passenger boarding on the non-operating side of the cab may have two, full-height corner posts on that side, one post located ahead of the stepwell and one located behind it, so that the corner post located ahead of the stepwell is permitted to fail provided that -

(A) The corner post located behind the stepwell shall have no more than 10 inches of longitudinal, permanent deformation; and

(B) There shall be no complete separation of that post, its connection to the underframe, its connection to either the roof structure or the anti-telescoping plate (if used), or of its supporting car body structure.

(4) The nominal weights of the object and the cab car or MU locomotive, as ballasted, and the speed of the object may be adjusted to impart the minimum of 120,000 foot-pounds of energy (0.16 megajoule) to be absorbed (Ea), in accordance with the following formula:

E_a = E₀−E_f

Where:

E₀ = Energy of initially moving object at impact = 1⁄2 m₁*V₀².

E_f = Energy after impact = 1⁄2 (m₁ + m₂)*V_f².

V₀ = Speed of initially moving object at impact.

V_f = Speed of both objects after collision = m₁*V₀/(m₁ + m₂).

m₁ = Mass of initially moving object.

m₂ = Mass of initially standing object.

(Figure 2 shows as an example a cab car or an MU locomotive having a weight of 100,000 pounds and the impact object having a weight of 14,000 pounds, so that a minimum speed of 17.1 mph would satisfy the collision-energy requirement.)

[75 FR 1230, Jan. 8, 2010, as amended at 83 FR 59228, Nov. 21, 2018]