Solution Summary: Incorporating Horizontal Round Grab Bars on Fixed Ladders for Three-point Control
Specifying to incorporate horizontal round bars onto fixed ladders during the design stages of a project is a prevention through design (PtD) process that addresses worker exposure to fall hazards. A horizontal round bar with power grip provides a greater safety margin for preventing a fall for a worker to grab than holding onto the vertical side railing of the ladder when a fall starts.
While climbing ladders, workers should put an emphasis in using the three-point control technique (Figure 1). Unlike the traditional three-point contact technique which vaguely states a worker should use at least three limbs for stable support during a climb, the three-point control technique specifically states a worker should hold a horizontal grip for horizontal support as opposed to a vertical support member (i.e. the side railing of a ladder). The approximate circumference of the horizontal bar should be 1 to 1.5 inches.
Figure 1. Three-point control technique (left) versus three-point contact technique (right). Source: www.fallsafety.com.
Workers climbing ladders are at risk of falling from heights. When workers use vertical support members on the ladder for contact support during climbing or descending, there may potentially be uncontrolled sliding of the hand(s) in the event of a fall. Robinovitch, Normandubm Stitzm et al. (2005) shows that a full physical human muscular response typically takes 1/3 second which is too late of a response for a sliding hand to fully grip the next fixed ladder rung (12 inches below) and attempt to stop a fall as it takes 1/4 second. The result of such falls can potentially cause fractures, sprains, strains, contusions, severe damage to internal organs and even death.
How Risks are Reduced:
Although the traditional three-point contact technique offers the reassurance of continuous hand contact with the side railing under static conditions, hand grip strength may be inadequate if there is a loss of balance or if one or both feet slip off a ladder rung during a climbing or descending transition. Using the three-point control technique allows for a worker to grasp the ladder more effectively so that he or she can bear the full weight of his or her body while also evenly distributing the body weight among three or four rungs.
Through the PtD concept, designing fixed ladder systems with horizontal round grab bars considers human factors while promoting the use of the effective three-point control technique. A CPWR-funded biomechanical study shows that holding a horizontal round object or grab bar with a horizontal power grip was found to provide greater safety margin for preventing a fall than holding onto a vertical side rail or object once a fall begins. These factors include handgrip strength capacities, the maximum breakaway force if a hand is forcibly pulled away from a support (Young, et al., 2009), as well as the size, shape, orientation and spacing of grab bars.
Depending on the rung size, the horizontal power grip has been shown to result in a 75% to 94% greater breakaway force than when gripping a vertical rail of the same shape and size (Young, Wooley,m Ashton-Miller, et al., 2012). Due to this safety factor, the risk is reduced via a properly designed horizontal power grip.
To learn more about the PtD concept of specifying fixed ladders or stairways when possible, please visit our other solution Considering Fixed Ladders and/or Stairways During the Design Phase.
Le, Jean Christophe, MPH - CPWR The Center for Construction Research and Training
Alliance Program Construction Roundtable
The designation of fixed ladders with the feature of properly-designed horizontal round bars installed onto buildings will be dependent on the guidance from a competent person with structural engineering experience and federal regulatory standards. For more information regarding system applicability and this grab bar feature, please contact the fixed ladder manufacturer directly. The information in this page was adapted from the Alliance Program Construction Roundtable
NIOSH Workplace Solutions Sheet
The National Institute of Safety and Health (NIOSH) has published a series of “Workplace Solutions”, which are easy-to-understand recommendations from NIOSH research results. Related to this Construction Solution, please find more information on: Supporting Prevention through Design (PtD) Using Business Value Concepts and Preventing Falls from Heights through the Design of Embedded Safety Features