Friction requirements for different climbing conditions in straight ladder ascending

Slips at the ladder bottom, which happen when the required friction to support activities on the ladder exceeds the available friction at the interface, are a major cause of injuries. The purpose of this study was to evaluate the effects of ladder inclined angle, climbing speed, ladder type, type of contact at the top of the ladder and body weight on the friction requirement at the bottom of the ladder. The results indicated that the ladder inclined angle and the climbing speed were the most and second most critical factors, respectively, in friction requirement among the factors evaluated. The required friction coefficient increased by 77% on average when the ladder inclined angle was decreased from 75° to 65°. Interventions to prevent ladder slips at their bases could include developing practical guidelines for the users to properly set up their ladders and reminding users not to rush on the ladder. The results also indicated that the contact at the top of the ladder and ladder type had minor effects on the required friction at the ladder base.