§ 238.721 Glazing. ( a ) *Cab glazing; end-facing.* ( 1 ) Each end-facing exterior window in a cab of a Tier III trainset shall comply with the requirements for Type I glazing in appendix A to part 223 of this chapter, except as provided in paragraphs (a)(2) through (4) of this section.
( 2 ) Instead of the large object impact test specified in appendix A to part 223, each end-facing exterior window in a cab shall demonstrate compliance with the following requirements of this paragraph (a): ( i ) The glazing article shall be impacted with a cylindrical projectile that complies with the following design specifications as depicted in Figure 1 to this subpart: ( A ) The projectile shall be constructed of aluminum alloy such as ISO 6362-2:1990, grade 2017A, or its demonstrated equivalent;
( B ) The projectile end cap shall be made of steel;
( C ) The projectile assembly shall weigh 2.2 pounds (−0, +0.044 pounds) or 1 kilogram (kg) (−0, +0.020 kg) and shall have a hemispherical tip. Material may be removed from the interior of the aluminum portion to adjust the projectile mass according to the prescribed tolerance. The hemispherical tip shall have a milled surface with 0.04 inch (1 mm) grooves; and
( D ) The projectile shall have an overall diameter of 3.7 inches (94 mm) with a nominal internal diameter of 2.76 inches (70 mm).
( ii ) The test of the glazing article shall be deemed satisfactory if the test projectile does not penetrate the windscreen, the windscreen remains in its frame, and the witness plate is not marked by spall.
( iii ) A new projectile shall be used for each test.
( iv ) The glazing article to be tested shall be that which has the smallest area for each design type. For the test, the glazing article shall be fixed in a frame of the same construction as that mounted on the vehicle.
( v ) A minimum of four tests shall be conducted and all must be deemed satisfactory. Two tests shall be conducted with the complete glazing article at 32 °F ± 9 °F (0 °C ± 5 °C) and two tests shall be conducted with the complete glazing article at 68 °F ± 9 °F (20 °C ± 5 °C). For the tests to be valid they shall demonstrate that the core temperature of the complete glazing article during each test is within the required temperature range.
( vi ) The test glazing article shall be mounted at the same angle relative to the projectile path as it will be to the direction of travel when mounted on the vehicle.
( vii ) The projectile's impact velocity shall equal the maximum operating speed of the Tier III trainset plus 100 mph (160 km/h). The projectile velocity shall be measured within 13 feet (4 m) of the point of impact.
( viii ) The point of impact shall be at the geometrical center of the glazing article.
( 3 ) Representative samples for large object impact testing of large Tier III end-facing cab glazing articles may be used instead of the actual design size, provided that the following conditions are met: ( i ) Testing of glazing articles having dimensions greater than 39.4 by 27.6 inches (1,000 mm by 700 mm), excluding framing, may be performed using a flat sample having the same composition as the glazing article for which compliance is to be demonstrated. The glazing manufacturer shall provide documentation containing its technical justification that testing a flat sample is sufficient to verify compliance of the glazing article with the requirements of this paragraph (a).
( ii ) Flat sample testing is permitted only when no surface of the full-size glazing article contains curvature with a radius less than 98 inches (2,500 mm), and when a complete, finished glazing article is laid (convex side uppermost) on a flat horizontal surface, the distance (measured perpendicularly to the flat surface) between the flat surface and the inside face of the glazing article is not greater than 8 inches (200 mm).
( 4 ) End-facing glazing shall demonstrate sufficient resistance to spalling, as verified by the large impact projectile test under the following conditions: ( i ) An annealed aluminum witness plate of maximum thickness 0.006 inch (0.15 mm) and of dimension 19.7 by 19.7 inches (500 mm by 500 mm) is placed vertically behind the sample under test, at a horizontal distance of 500 mm from the point of impact in the direction of travel of the projectile or the distance between the point of impact of the projectile and the location of the engineer's eyes in the engineer's normal operating position, whichever is less. The center of the witness plate is aligned with the point of impact.
( ii ) Spalling performance shall be deemed satisfactory if the aluminum witness plate is not marked.
( iii ) For the purposes of this subpart, materials used specifically to protect the cab occupants from spall (*i.e.,* spall shields) shall not be required to meet the flammability and smoke emission performance requirements of appendix B to this part.
( 5 ) Each end-facing exterior window in a cab shall, at a minimum, provide ballistic penetration resistance that meets the requirements of appendix A to part 223.
( 6 ) Each end-facing exterior window in a cab shall be permanently marked, before installation, in such a manner that the marking is clearly visible after the material has been installed. The marking shall include: ( i ) The words “FRA TYPE IHS” to indicate that the material has successfully passed the testing requirements specified in this paragraph (a);
( ii ) The name of the manufacturer; and
( iii ) The type or brand identification of the material.
( b ) *Cab glazing; side-facing.* Each side-facing exterior window in a cab of a Tier III trainset shall— ( 1 ) Comply with the requirements for Type II glazing contained in appendix A to part 223 of this chapter, for large-object impact; and
( 2 ) Maintain the minimum ballistics penetration resistance as required for end-facing glazing in paragraph (a)(5) of this section.
( c ) *Non-cab glazing; side-facing.* ( 1 ) Except as provided in paragraph (c)(2) of this section, each side-facing exterior window in other than a cab shall comply with the requirements for Type II glazing contained in appendix A to part 223 of this chapter.
( 2 ) Instead of the requirements specified in paragraph (c)(1) of this section, a side-facing exterior window intended to be breakable and serve as an emergency window exit may comply with an alternative standard that provides an equivalent level of safety and is approved for use by FRA.
( d ) *Glazing securement.* Each exterior window shall remain in place when subjected to: ( 1 ) The forces due to air pressure differences caused when two trains pass at the minimum separation for two adjacent tracks, while traveling in opposite directions, each train traveling at the maximum authorized speed; and
( 2 ) The impact forces that the exterior window is required to resist as specified in this section.
( e ) *Glazing certification.* ( 1 ) Each manufacturer that provides glazing materials, intended by the manufacturer for use in achieving compliance with the requirements of this section, shall certify that each type of glazing material being supplied for this purpose has been successfully tested. Tests performed on glazing materials for demonstration of compliance with this section, relied on by the glazing manufacturer in furtherance of certification, may be performed by either: ( i ) An independent third-party (laboratory, facility, underwriter); or
( ii ) The glazing manufacturer, by providing FRA the opportunity to witness all tests by written notice at least 30 days prior to testing.
( 2 ) Any glazing material certified to meet the requirements of this section shall be re-certified by the same means (as originally certified) if any changes are made to the glazing that may affect its mechanical properties or its mounting arrangement on the vehicle.
( 3 ) All certification/re-certification documentation shall be made available to FRA upon request.