Feasibility of center LATCH

Abstract

This paper explores the geometric feasibility of installing dedicated lower anchors in the center rear seating positions of vehicles. Analysis was based on a previous research study in which the lateral spacing of seat belt and LATCH lower anchorages were measured in 85 model year 2010-2011 vehicles. The goal of this study was to determine how many vehicles would have the physical space to incorporate a third set of dedicated lower anchors in the center seating position for child restraint installation. Usability of all of the lower anchors, as well as the seat belts, was also considered. To begin, nine vehicles that currently have dedicated lower anchors in the center position were reviewed. The distances between all seat belt anchors and lower anchors across the vehicle sample were also analyzed to identify spacings that are currently feasible in production. The arrangement of seat belt and lower anchor hardware across the rear seat was also reviewed with respect to usability. Based on these analyses, a lateral distance between the outboard webbing and outboard lower anchor of 75 to 100 mm is common. The suggested minimum distance between lower anchors and seat belt hardware is 25 mm. Based on these dimensions, vehicles with 710 mm or more between the outboard lower anchor centerlines (OBLACL) should have sufficient space to provide three sets of usable, dedicated lower anchors in the right, center, and left seating positions. Providing the highest level of usability with regard to use of seat belt or LATCH hardware in adjacent seating positions would be achieved by placing each pair of lower anchors between the webbing and buckle hardware for the seating position. If the OBLACL is less than 710 mm, an improvised center LATCH position (permitting use of the inboard lower anchors from the outboard seating positions to secure a child restraint in the center seating position) may be feasible. The maximum spacing of this improvised center LATCH position would be 480 mm. If a vehicle allowed an improvised center LATCH position, placing the inboard lower anchor between the outboard buckle and nearest center seat belt hardware would maximize usability of the seat belt in the outboard seating position and lower anchors in the center seating position.