Objective: The purpose of this study is to analyze the lifting work posture and the load on the lumbar spine in a low-roof delivery vehicle in which couriers must bend their neck and waist when handling packages.
Background: Due to COVID-19, the volume of parcel deliveries has increased significantly recently, and for safety reasons, some apartment complexes prohibit ground parking of delivery vehicles and instead require them to perform delivery tasks in underground parking lots. At this time, ordinary delivery vehicles with high garages cannot enter the underground parking lot, so there is no choice but to use lowroof delivery vehicles. In low-roof delivery vehicles, uncomfortable postures on the back and neck of couriers are inevitable when loading and unloading parcel items, which makes work uncomfortable and increases the possibility of musculoskeletal diseases.
Method: In this study, we conducted experiments by setting the ceiling height of the delivery vehicle at three stages: 1,300, 1,600, and 1,900mm. Six men aged 20~30 who participated in the experiment were asked to lift and put down a square box weighing 15kg twice under each ceiling height. A three-dimensional motion analysis device was used to track 24 markers attached to the joints of the subjects, and then the flexion angle of the waist and the flexion angle of the neck were measured. In addition, the angle of each joint was used in the 3DSSP program to calculate the compression force at L5/S1.
Conclusion: The lifting work at a height of 1,300mm in delivery vehicles showed that the compression force at the average L5/S1 based on 3DSSPP exceeded the standard value of 3,400N. In view of this, parcel delivery using low-roof delivery vehicles, which is currently a social problem, should be avoided.
Application: The results of this study can be used as basic data for designing the ceiling height of delivery vehicles and may be utilized in the establishment of relevant laws and policies.