Child Posture and Belt Fit in Second-Row Vehicle Seats

Abstract

Posture and belt fit were measured for 40 children ages 5 to 12 years across two phases of testing involving six vehicles and six boosters, including one integrated booster. The three-dimensional locations of landmarks on the children, belt, and seat were recorded in each condition. Belt anchorage locations and other vehicle dimensions were recorded to characterize the seating environments. Lap belt fit was quantified by the location of the edge of the belt relative to the anterior-superior iliac spine landmark on the pelvis. Shoulder belt fit was measured as the lateral distance of the belt from the occupant centerline at the height of the suprasternale landmark. Lap belt fit without a booster was generally poor, with the belt lying fully above the pelvis for most children in most conditions. Belt positioning boosters improved lap belt fit in all conditions and improved shoulder belt fit for many combinations of children and vehicle. Taller children generally experienced better belt fit, but the effects were small compared to the benefits of using a booster. Belt fit scores were correlated with predictions based on previous laboratory studies using child stature and vehicle geometry as inputs. Mean belt fit scores were well correlated across conditions with predictions based on ATD measurements.