Recent in-house benchmarking research has shown that seatbelt buckles in the rear seats of some passenger vehicles are becoming shorter and recessing further into the seat cushion in a possible effort to improve restraint geometry, achieve better Gabarit fit, or achieve other objectives. Despite the evident benefits associated with this trend, a major drawback could be that this recessed configuration reduces accessibility to the buckle for child occupants in booster seats.

Therefore, the objectives of this study were to:​

1. Perform a series of usability studies with children to evaluate how the recessed position of the seatbelt buckle compares to an elevated position.

2. Demonstrate the effectiveness of a motorized adjustable buckle (seatbelt buckle technology that extends or retracts via an electric motor) as a possible way to maintain the intended recessed buckle geometry in-use, while simultaneously providing improved buckle accessibility for child occupants in booster seats.

A series of studies were conducted with a mounting fixture that simulated the rear right side seat of a midsized sedan with a booster seat. The fixture was equipped with a motorized adjustable buckle which replicated two buckle modes – recessed and elevated. Children of varying age, height and weight ranges were asked to buckle themselves with the buckle in both positions and observations were made of the number of latch attempts, latch durations, occupant preferences and difficulty level.

Evaluations show that the elevated mode was preferred among the sample size due to its ease of accessibility. One specific seating configuration was used for this study – midsize right hand rear row sedan seat and average size booster seat. In order to universally confirm the study’s hypothesis, varying combinations of seat sizes and booster seats would have to be further studied.

The study also suggests that child booster seat and vehicle seat designers should increase coordination of their respective product designs to better suit the abilities of child occupants. Furthermore, motorized buckles may be a viable alternative to the conundrum of maintaining the in-use buckle position intended by certain manufacturers while improving the accessibility of seatbelt buckles for child occupants in booster seats.