Evaluation of Proposed Protocols for Assessing Vehicle LATCH System Usability 2013-01-1155

This project assessed current or proposed protocols for improving the usability of LATCH (Lower Anchors and Tethers for Children). LATCH hardware in the left second-row position of 98 2011 or 2010 model-year vehicles was evaluated using ISO and SAE LATCH usability rating guidelines. Child restraint/vehicle interaction was assessed using ISO and NHTSA proposed procedures.

ISO ratings of vehicle LATCH usability ranged from 41% to 78%, while vehicles assessed using the SAE draft recommended practice met between 2 and all 10 of the recommendations that apply to all vehicles. There was a weak relationship between vehicle ISO usability ratings and the number of SAE recommended practices met by a vehicle. Twenty vehicles with a range of vehicle features were assessed using the ISO vehicle-child restraint form and 7 child restraints; ISO vehicle-child restraint interaction scores ranged from 14% to 86%. Twelve vehicles and 7 child restraints were evaluated using the proposed NHTSA fit criteria in the left second-row position. Most styles of child restraints met the criteria in most vehicles, with the exception that rear-facing convertible restraints did not meet the proposed criteria in most vehicles.

Testing with volunteers using 12 vehicles and three child restraints indicated that the overall ISO vehicle rating, ISO vehicle-child restraint interaction rating, or the number of SAE recommended practices that were met were not associated with the rate of correct child restraint installations performed by volunteers. Vehicle-child restraint pairings meeting the proposed NHTSA fit criteria had error-free installations four times as often as those that did not, but still few were error-free (16% vs. 4%).