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Interpretation ID: 244424aogm

    Mr. Martin Krenn
    Concept Technologic GmbH
    Fischeraustrasse 13
    A-8051 Graz Austria


    Dear Mr. Krenn:

    This is in response to several questions contained in your electronic mail message to Ms. Karen Nuschler regarding test procedures under the head impact protection provisions contained in Standard No. 201, Occupant protection in interior impact. Your electronic mail message states that your company is developing a motorhome. The development of this vehicle has raised questions regarding the location of targets and target zones and test procedures under Standard No. 201.

    Under the provisions of Standard No. 201, vehicles must meet certain performance criteria when specific targets in the interior are struck by an instrumented headform representative of a human head. The targets are located by a mapping procedure found in the Standard. Once a target point is located, a 12.7 mm target circle centered on the target point serves as the test target. Any part of that target circle may be struck by the headform during a test.

    Your first question relates to the proper procedure for locating targets on the upper roof. The head protection requirements of Standard No. 201 require manufacturers to meet performance requirements only at those targets that are located using the procedures found in S10 of the standard. In the case of the upper roof, S10.9 specifies that the upper roof target (target UR) may be located anywhere within the upper roof zone. Therefore, once the boundaries of the upper roof zone are established as set forth in the standard, UR may be located at any point within those boundaries. Your message contains a photograph of the interior of a vehicle. Referring to the photograph, you ask if a point on an area of the vehicle depicted in the photo represents the proper location of the transverse vertical plane described in S8.15(b).

    The boundaries of the upper roof are located through use of the procedures set forth in S8.15(a) through (h). S8.15(b) directs that a transverse vertical plane, plane B, be located at the rearmost point where it contacts the interior roof (including trim) at the vehicle centerline. Once located, plane B serves as the rearmost boundary of the upper roof. The photograph incorporated into your electronic mail message depicts what appears to be the cab area of a motorhome and shows the passenger side B-pillar and what appears to be the rear of the front outboard passenger seat. The photograph also depicts that the interior roof of the vehicle is comprised of at least two sections. The first section is located over the driver and front passenger seat and continues from the front header to the rear edge of the B-Pillar. This section meets a transverse vertical panel that extends upward until it contacts the remainder of the roof, which then continues to the rear of the vehicle. A drawing of the vehicle also embedded in your message indicates that this front section of the interior roof also serves as the floor of a storage compartment that is enclosed on the sides and top by the raised exterior roof of the vehicle.

    A notation and arrow on the photograph point to an area on the rearmost section of the interior roof segment located over the driver and passenger seats. You ask if this point is the proper location for plane B under S8.15(b). The answer is no. The area depicted in your photograph is not located at the rearmost point where a the transverse plane "B" contacts the interior roof. The photographs and drawings in your email message indicate that the point you have marked is located at what appears to be the rearmost point of a section of the interior roof. However, the interior roof of the vehicle does not terminate at this point. Although the interior roof is bisected by a transverse vertical section that serves as the door for an overhead storage compartment, the interior roof extends rearward from the aft edge of this door to the rear of the vehicle. For the purposes of defining the upper roof under S8.15(b), the entire interior roof, not just the rearmost point of a discontinuity in the interior roof, must be considered when locating plane B.

    It should be noted, however, that because the vehicle in question is a motorhome, the range of potential targets within the upper roof is restricted by S6.3(c). S6.3(c) provides that the performance requirements found in S6.1 and S6.2 do not apply to any target located rearward of a vertical plane 600 mm behind the seating reference point of the driver's seating position in an ambulance or a motor home. As the vehicle described in your message appears to be a motorhome for the purposes of Standard No. 201, it must only comply with the performance requirements of S6.1 and S6.2 for those targets located forward of the transverse vertical plane located less than 600 mm to the rear of the seating reference point.

    Your message also indicates your concern about the location of the side rail target known as SR3 within your vehicle. You correctly observe that the procedure for locating this target is set forth in S10.7 of Standard No. 201. However, you note that if you follow this procedure to locate the target in your companys product, the particular configuration of the roof results in the SR3 target being located well above the actual side rail. As indicated by the photographs incorporated in your message, the use of the procedure in S10.7 results in the target being located some distance above the side rail. You further indicate that these target locations are so high in the vehicle that it is unlikely that they would even be struck by a standing person in the event of a crash. As it appears unlikely that an occupant might strike this target location, you ask what procedure the National Highway Traffic Safety Administration (NHTSA) would follow in locating and testing this target.

    When NHTSA performs compliance testing, it does so in accordance with the procedures and requirements found in the applicable standard. In the case of the vehicle depicted in your electronic mail message, or a similar vehicle, the agency would perform testing using the target location dictated by S10.7.

    Your last question regards the proper procedure for determining the proper vertical approach angles for testing. Your message notes that the procedure for determining the maximum vertical approach angle is found in S8.13.4.2 of Standard No. 201. You ask what the proper procedure would be in a case where a target was relocated to a point where rotation of the free motion headform (FMH) in accordance with S8.12.4.2(a) does not result in any contact between the lower portion of the FMH and the vehicle. In such a case, you ask if the target must be relocated again or if the test should be performed without rotating the FMH downward by 5 degrees as set forth in S8.12.4.2(b)(1).

    S8.13.4 specifies a range of permissible horizontal and vertical approach angles that constrain the direction of the FMH when approaching a particular type of target. If an approach angle for a particular target is within the range of permissible approach angles, that angle may be used in testing a target area. S8.13.4.2(b) directs that one step in determining the maximum vertical approach angle is to rotate the FMH while keeping the forehead impact zone in contact with the target until the lowerportion of the FMH contacts the vehicle. Once this angle is derived, S8.13.4.2(b)(1) and S8.13.4.2(b)(2) direct that the maximum vertical approach angle is the angle that results from rotating the FMH downward by either 5 or 10 degrees from the angle found by following S8.13.4.2(b).

    In a case where the configuration of the vehicle is such that the rotation of the FMH specified in S8.12.4.2(b) does not result in any contact between the lower portion of the FMH and the vehicle, the FMH should be rotated upward until the forehead impact zone is no longer in contact with any part of the target. For the purposes of S8.12.4.2(b), NHTSA considers the angle at which the forehead impact zone loses contact with any part of the target to be equivalent to the angle found when the FMH can no longer be physically rotated upward. If a target is located above a window opening or is otherwise located where there is no vehicle structure to impede upward rotation, the lack of an impediment to this upward rotation should not, in NHTSAs view, require relocation of an otherwise valid target.

    As your company is apparently in the process of developing a motorhome, you should be aware that the Recreation Vehicle Industry Association (RVIA) filed a petition for rulemaking on October 4, 2001, requesting that the agency modify Standard No. 201 to exclude conversion vans and motor homes with gross vehicle weight rating of 4,536 kilograms (10,000 pounds) or less, from the application of the upper interior head protection requirements of the Standard. The National Truck Equipment Association (NTEA) filed a petition for rulemaking on November 27, 2001, seeking similar relief for multi-stage vehicles. Both petitions requested that NHTSA extend the existing phase-in for manufacturers of multi-stage vehicles from September 1, 2002, to March 1, 2004. By letters dated March 28 and April 5, 2002, NHTSA indicated it was granting the petitions. The agency is currently embarking on a rulemaking proceeding to address the issues raised in the petitions and anticipates issuing a notice regarding its response to the petitions in the near future. In the interim, the agency published a notice in the Federal Register on June 18, 2002, (67 FR 41348) providing final stage manufacturers and alterers with an additional year to comply with the upper interior head protection requirements.

    I hope that this is responsive to your inquiry. If you have any questions, please contact Otto Matheke of this office at (202) 366-5263 or by electronic mail at omatheke@nhtsa.dot.gov.

    Sincerely,

    Jacqueline Glassman
    Chief Counsel

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    d.8/22/02