Section 238.705 - Dynamic collision scenario(a)General. In addition to the requirements of § 238.703 , occupied volume integrity (OVI) shall also be demonstrated for each individual vehicle in a Tier III trainset through an evaluation of a dynamic collision scenario in which a moving train impacts a standing train under the following conditions: (1) The initially-moving trainset is made up of the equipment undergoing evaluation at its AW0 ready-to-run weight;(2) If trainsets of varying consist lengths are intended for use in service, then the shortest and longest consist lengths shall be evaluated;(3) If the initially-moving trainset is intended for use in push-pull service, then, as applicable, each configuration of leading vehicle shall be evaluated separately;(4) The initially-standing train is led by a rigid locomotive and also made up of five identical passenger coaches having the following characteristics:(i) The rigid locomotive weighs 260,000 pounds and each coach weighs 95,000 pounds;(ii) The rigid locomotive and each passenger coach crush in response to applied force as specified in Table 1 to this section; and(iii) The rigid locomotive shall be modeled using the data inputs listed in appendix H to this part so that it has a geometric design as depicted in Figure 1 to appendix H to this part;(5) The scenario shall be evaluated on tangent, level track;(6) The initially-moving trainset shall have an initial velocity of 20 mph if it is an integrated trainset, or an initial velocity of 25 mph if the lead vehicle of the trainset is not part of the integrated design;(7) The coupler knuckles on the colliding equipment shall be closed and centered;(8) The initially-moving trainset and initially-standing train consists are not braked;(9) The initially-standing train has only one degree-of-freedom (longitudinal displacement); and(10) The model used to demonstrate compliance with the dynamic collision requirements must be validated. Model validation shall be documented and submitted to FRA for review and approval.(b)Dynamic collision requirements. As a result of the impact described in paragraph (a) of this section- (1) One of the following two conditions must be met for the occupied volume of the initially-moving trainset: (i) There shall be no more than 10 inches of longitudinal permanent deformation; or(ii) Global vehicle shortening shall not exceed 1 percent over any 15-foot length of occupied volume.(2) If Railway Group Standard GM/RT2100, Issue Four, "Requirements for Rail Vehicle Structures," Rail Safety and Standards Board Ltd., December 2010, is used to demonstrate compliance with any of the requirements in §§ 238.733 , 238.735 , 238.737 , or 238.743 , then the average longitudinal deceleration of the center of gravity (CG) of each vehicle in the initially-moving trainset during the dynamic collision scenario shall not exceed 5g during any 100-millisecond (ms) time period. The maximum interval between data points so averaged in the 100-ms time period shall be no greater than 1-ms.(3) Compliance with each of the following conditions shall also be demonstrated for the cab of the initially-moving trainset after the impact: (i) For each seat provided for an employee in the cab, and any floor-mounted seat in the cab, a survival space shall be maintained where there is no intrusion for a minimum of 12 inches from each edge of the seat. Walls or other items originally within this defined space, not including the operating console, shall not further intrude more than 1.5 inches towards the seat under evaluation;(ii) There shall be a clear exit path for the occupants of the cab;(iii) The vertical height of the cab (floor to ceiling) shall not be reduced by more than 20 percent; and(iv) The operating console shall not have moved more than 2 inches closer to the engineer's seat; if the engineer's seat is part of a set of adjacent seats, the requirements of this paragraph (b)(3) apply to both seats. Table 1-Force-Versus-Crush Relationships for Passenger Coach and Conventional Locomotive
| Vehicle | Crush
(in) | Force
(lbf) |
| Passenger Coach | 0 | 0 |
| 3 | 80,000 |
| 6 | 2,500,000 |
| Conventional Locomotive | 0 | 0 |
| 2.5 | 100,000 |
| 5 | 2,500,000 |