News

NHTSA Proposes Changes to Improve LATCH

Can regulatory amendments help LATCH meet its full potential?

This article originated in the January/February 2015 issue of Safe Ride News.

A line drawing showing a vehicle seat with 3 sets of lower anchors.

On January 23, NHTSA published a Notice of Proposed Rulemaking (NPRM) regarding updates it plans for FMVSS 225 and 213 in order to improve the usability of the LATCH system. This NPRM is an important step toward improving ease of use and accessibility of lower and tether anchors, a topic that hasn’t been addressed through regulation since LATCH was initially introduced 15 years ago. It outlines some basic proposals for new regulations from NHTSA and seeks comment on the necessity of further regulation.

Although this is the first step of the process that involves the public, NHTSA has been conducting research and analysis over the past few years as the basis for the proposed rule changes. The documents for this supporting research, as well as the NPRM document, are available to view at www.regulations.gov (Docket #NHTSA-2014-0123). Among the posted documents are reports on how LA spacing and TA location affect loads on anchor hardware and the feasibility of center LATCH.

NHTSA requests comments on any aspect of the NPRM through March 24, 2015. This provides an opportunity for any citizen who has struggled with using LATCH to provide feedback to NHTSA before amendments are finalized.

Proposals Affecting Vehicle LAs

  • LA clearance, force, and depth: To make lower anchors (LAs) more usable, NHTSA considered the approaches of three groups (the Society of Automotive Engineers, the International Standards Organization, and the University of Michigan Transportation Research Institute [UMTRI]). Of these, NHTSA decided to base its proposals mainly on the UMTRI approach because that group’s work also demonstrated that particular LA features have a measurable impact on CR installations in user trials. (The study, “Keys to Better LATCH,” was conducted in partnership with the Insurance Institute for Highway Safety and can be found in the April 12, 2012, issue of Status Report. It was also covered in SRN (March/April 2012) and is summarized on page 76 of the 2015 LATCH Manual.) NHTSA also drew from these groups to identify the tools that manufacturers would be required to use to measure whether vehicles are in compliance.

Based on the usability study, NHTSA proposes changes to LA-related regulations in FMVSS 225 in these three ways:

  • Clearance Angle: A proposed requirement is intended to assure easy access to the LA. Some anchors are currently hard to connect to due to interference from parts of the seat structure or very stiff cushion material. A new tool would be used to make sure that there’s space (or soft padding) in the area above the anchor bar.
  • Attachment Force: Another new requirement would put a maximum of 40 pounds (178 newtons) on the force needed to push an LA attachment onto an LA. Another new tool will measure the attachment force.
  • Anchorage Depth: FMVSS 225 already specifies how deep an LA can be relative to a reference point near the seat bight, but the UMTRI study and feedback to NHTSA from the field indicate that that range is too liberal, and LAs are often too deep behind the seat bight for consumers to use easily. Therefore, NHTSA proposes to require LAs be placed within the seat bight no deeper than 2 cm (0.8 in.). Again, a special tool has been developed to measure this. (Note: NHTSA’s current limit on how far forward of the bight an LA can be would remain in force.)
  • LA Markings: Currently, FMVSS 225 only requires marking those LAs that are not visible. Markings, when provided, can (and do) differ in appearance from one vehicle model to another. Since this can contribute to consumer confusion, NHTSA proposes to require all LAs to be marked, and that the mark be standardized. The meaning of the mark would be explained in the owner’s manual.
  • LA Exclusions: As originally written, FMVSS 225 was sensitive to the possibility that the transmission and/or suspension components of some vehicles would be in the required zone for LAs, making LAs difficult to install. As a result, LAs were not required in these models. NHTSA proposes deleting this exception due to the fact that manufacturers have now gained ample experience in designing and installing LAs and should be able to work around these types of challenges.

Proposals Affecting Vehicle TAs

  • TA design: Currently, FMVSS 225 does not place any requirement on the design of TAs, other than that the TA be able to accept the required CR tether hook. The NPRM proposes to require all TAs to be “rigid bar(s) of any cross-section shape.” While this criterion describes most TAs, it disallows the cable loop and cargo strap types currently found in many trucks and SUVs. This proposed change is intended to make the appearance of TAs more uniform so they are easier to identify. Although the agency has tentatively decided not to specify dimensions for TAs (in order to give manufacturers some design flexibility to meet TA strength requirements), it requests comments on this issue.
  • TA allowed zone: The zone for TA locations would no longer allow for TAs to be placed underneath vehicle seats. (Although this TA location is not found in recent models, NHTSA makes this proposal to prevent such a design from reappearing.) NHTSA estimates that 78 percent of TAs are located on the seatback and rear-window shelf, and it has tentatively decided to continue to permit placement in other locations (such as the roof, floor, or back wall) in order to allow vehicle makers to select an appropriately strong location that is also convenient for use in the vehicle. Note: NHTSA also researched whether the allowable zone should be adjusted on the basis of TA performance. In sled tests, which are described in detail in the NPRM, NHTSA found no difference in performance when CRs were anchored to TAs in a variety of extreme locations within the allowable zone.
  • TA accessibility: NHTSA proposes that TAs must be in a location that’s accessible without moving any vehicle component, such as the vehicle seat or carpeting. However, a cover like a cap or flap would still be acceptable provided it was marked and accessible without use of any tools (including a screwdriver or coin).
  • TA clearance: NHTSA is concerned about the interference of vehicle parts around the TA, especially head restraints. Based on analysis of the UMTRI research, it proposes that a minimum distance of 6.5 inches be required between the TA and a reference point on the front of the vehicle seatback in order to allow enough distance to tighten the tether strap properly. (See “Proposals Affecting CRs,” next page, for corresponding limits on tether assembly length.)
  • TA marking: FMVSS 225 currently does not require TAs to be marked, which may contribute to the problem of lack of awareness. NHTSA proposes that the standard be amended to require all TAs to be marked, even if plainly visible. Either of two anchor symbols could be used. The mark would have to be placed so that it is aligned with the TA bar with the distance from the nearest edge of the mark to the center of the bar not to exceed 1 inch (in order to eliminate confusion with other vehicle hardware that can frequently be mistaken for a TA). TAs with a cover that can be removed must have a marking both on the cover and underneath the cover near the TA (in case the cover becomes lost). An explanation of the symbol would be required in the vehicle owner’s manual.
  • TA exclusions: NHTSA proposes deleting the exclusion of convertible vehicles from the requirement to provide TAs. The agency says that the challenges that existed when TAs were first required can more easily be overcome after years of experience. (Indeed, TAs have been designed into several convertible models already.)
  • TA use: NHTSA has extensively studied tether performance and has concluded that use of tethers on forward-facing CRs should be encouraged for all installations without limitation of child weight. NHTSA requests comments on whether instructions for CR and vehicle manuals should be required to include this recommendation. (Most CR manuals already do.)

Proposals Affecting CRs

Most changes proposed affect vehicles and FMVSS 225, but a few have corresponding changes that would affect CRs and amend FMVSS 213.

  • Tether hardware assembly length: To improve compatibility between vehicles and CRs, NHTSA proposes to require the length of the tether hook and adjuster hardware to be no longer than 6.5 inches (matching the minimum distance from a point on the front of the seatback it proposes for the TA placement in FMVSS 225). UMTRI estimates that this would require a redesign for roughly 30 percent of CR tethers.
  • Tether hook and LA connector marking: NHTSA proposes to require the universal symbols (shown on page 6) it has promoted for marking LAs and TAs in vehicles to also appear with the corresponding CR hardware. The LA symbol would appear on the LA connector. Either of the symbols for tethering would appear on the tether hook or within an inch of it on the strap or on a tag. An explanation of the symbols would be required in the CR owner’s manual.

Additional Comments Requested

In addition to the changes NHTSA has proposed, it also requests comments on many other subjects, including:

  • Center use of LATCH: NHTSA has analyzed research on the topic of center LATCH, but has not made any proposals. Instead, it would like the public to comment on the importance of LATCH in the center and the merits of three possible approaches:
    1. Requiring one of the LATCH systems already required to be in a center position.
    2. Requiring LATCH to be added to the center position, in addition to the two systems usually found in the outboard positions.
    3. Requiring the inner bars of two outboard LATCH positions to be usable as a variable-width center LATCH option (which NHTSA calls a “simulated child anchorage system”). The supporting documentation includes studies performed by NHTSA that show no degradation in CR performance when bars are spaced up to 20.4 inches apart.
  • LATCH in the third row: Should LATCH systems and/or TAs be required in the third row of vehicles when such a row exists? Should more LATCH positions be required when the vehicle has more than two rows?
  • LATCH terminology: NHTSA would like to hear public opinion about whether use of uniform terminology would improve consumer education efforts and increase the likelihood of proper CR use. It proposes to use “lower anchor” and “tether anchor” for components in the vehicle, and “lower anchor attachment” and “tether” for the parts on the CR. A lower anchor attachment would be comprised of a “lower anchor connector” and (for flexible systems) a “lower anchor strap.” A tether would be comprised of a “tether hook” and a “tether strap.” (Note: SRN coordinated the terminology used in the 2015 LATCH Manual with NHTSA in order to be in alignment with this proposed terminology.)

Timing

NHTSA has asked for public comments by March 24, 2015. After that, the timing of the final rule will depend on the nature of the comments and whether further research is needed. The NPRM proposes an effective date of three years after the final rule has been published for both vehicle and CR manufacturers. Early compliance would be allowed after 60 days.

Reference:

The NPRM, supporting documents, and public comments (as they are submitted) can be viewed by going to www.regulations.gov and searching Docket No. NHTSA-2014-0123.

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