49 CFR 238.707: Override protection.

(a) Colliding equipment. (1) Using the dynamic collision scenario described in § 238.705(a), anti-climbing performance shall be evaluated for each of the following sets of initial conditions:

(i) All vehicles in the initially-moving trainset and initially-standing train consists are positioned at their nominal running heights;

(ii) The lead vehicle of the initially-moving trainset shall be perturbed laterally and vertically upwards by 3 inches at the colliding interface; and

(iii) The lead vehicle of the initially-moving trainset shall be perturbed laterally and vertically downwards by 3 inches at the colliding interface.

(2) For each set of initial conditions specified in paragraph (a)(1) of this section, compliance with the following conditions shall be demonstrated after a dynamic impact:

(i) The relative difference in elevation between the underframes of the colliding equipment in the initially-moving trainset and initially-standing train consists shall not change by more than 4 inches; and

(ii) The tread of any wheel of the first vehicle of the initially-moving trainset shall not rise above the top of the rail by more than 4 inches

(b) Connected equipment override. (1) Using the dynamic collision scenario described in § 238.705(a), anti-climbing performance shall be evaluated for each of the following sets of initial conditions:

(i) All vehicles in the initially-moving trainset and initially-standing train consists are positioned at their nominal running heights;

(ii) One vehicle is perturbed laterally and vertically upwards by 2 inches, relative to the adjacent vehicle, at the first vehicle-to-vehicle interface in the initially-moving trainset; and,

(iii) One vehicle is perturbed laterally and vertically downwards by 2 inches, relative to the adjacent vehicle, at the first vehicle-to-vehicle interface in the initially-moving trainset.

(2) For each set of initial conditions specified in paragraph (b)(1) of this section, compliance with the following conditions shall be demonstrated after a dynamic impact:

(i) The relative difference in elevation between the underframes of the connected equipment in the initially-moving trainset shall not change by more than 4 inches; and

(ii) The tread of any wheel of the initially-moving trainset shall not rise above the top of rail by more than 4 inches.