A New Grip on Reality

David W. Cooper

At the recent April 28–May 2 meeting of the ICC/ANSI A117 Accredited Standard Committee in St. Louis, MO, a proposal to allow Type II handrail profiles was approved for inclusion in the next draft of the standard. The proposal appears in the second draft of the standard that is now published for public comment.

The Type II handrail classification added to the standard is used in the building codes to describe prescriptive design specifications for handrails larger than 6-1/4 inches (159 mm) in perimeter that have graspable finger recesses on both sides. Type I is the new classification for those handrails currently allowed in the standard. The Type II specifications address a range of dimensions defining the position and minimum depth of the required recesses in relation to the crown height and the widest point of the rail above the recesses. The dimensions limits are based on the range of samples tested to be equivalently graspable or superior to those handrails currently allowed in the A117.1 standard.

This graphic aid for designing compliant Type II handrails is published and available at no cost by downloading the SMA Visual Interpretation of the IRC at www.stairways.org

Function

Although the definition of "handrail" in the building code recognizes but two of these functions it is generally agreed that handrails provide for

Guidance
Stabilization
Arresting a fall
Pulling

A stabilizing grip is critical to use for each of the functions other than guidance. For those with disabilities it is helpful to extend the handrail beyond the walking surface where the assist is needed to accommodate attaining a grip on the rail and a stable posture prior to initiating the use of a stair or ramp at either end. Other related concerns for those with disabilities include the following:

Handrail should be continuous throughout the needed distance of the walking surface and
The shape of an object is critical to the type of grip(s) that can be used
Objects should be designed to accommodate more than one type of grip
Considering alternative grips is advantageous to those with disabilities
A wider/larger diameter grip can be advantageous to those that cannot close their hand around smaller objects

Type II handrails provide new universal design options in this regard

Type I handrails are used with a full power grip encircling the handrail. In particular, contact of the fingers with the bottom of the handrail is essential to maximize the potential graspability of these shapes.

Type II handrails utilize a power-span grip, a modification of the power grip that is open at the bottom. This grip does not require contact with the bottom of the rail. Instead the fingers and thumb have purchase in the required opposing side recesses providing graspability equivalent or superior to the power grip used on Type I handrails. The graspable recesses also provide for use of an alternative hook grip by allowing the fingers a point of purchase within the recess that can stabilize transverse forces perpendicular to the rail as experienced when leaning away from the handrail.

Type I Danger Countered by Type II Advantage

Brackets, balusters, panels, a balustrade or posts that are attached to the bottom must be used to support all handrails. These supports can compromise the effective grip that can be maintained in use and endanger the user by obstructing the formation of a stabilizing grip when needed in the event of loss of balance. They can also interrupt the users ability/willingness to maintain continuous contact in the form of the needed power grip on Type I handrails. However because of the required recess locations of Type II handrails the supports attached to the bottom of the rail are lower, out of the range of extended fingers and do not cause obstructions to grip formation. Type II handrails can be also be utilized to include persons that cannot close their hand to securely grip smaller Type I rails.

Handrail brackets support a wall mounted metal rail.

Balusters and posts can interfere in gripping round handrails.

Status Quo Still an Option

No changes are being made to the current rails allowed or the exception to allow blocking up to 20% of the bottom of the rail that perpetrates the feasible use of Type I rails. The exception, unrelated to any researched level of safety, is an arbitrary compromise to accommodate practical methods of attachment. Type I handrails can be less than 80% effective. The problem is most severe when fingers must carefully straddle balusters placed close together. While moving on an adjacent walking surface such designs are impractical requiring fingers and thumb to fit between supports, nearly impossible for those with low vision. The needed power grip is ineffective and the hook grip cannot find purchase on the unobstructed upper portion of the grip surface. However that portion of the Type I grip surface is available for guidance in hope that your hand is in the right place at the right time to form a stabilizing grip. It is unlikely one can predict the critical occasions of loss of balance however it maybe possible to predict that such occasions would be more frequent for those with certain disabilities.

In the case of designing assists such as handrails and grab bars for those with disabilities the concern for providing a continuous grip surface is well understood. Obstructions in the bottom of Type I handrail at best promotes intermittent release of the users grasp and at its worst discourages use entirely. Other options, available for centuries, have now been proven to be equivalent or superior. It is hard to understand why we would continue to risk the exclusion of so many that could use them. It is not only contrary to the concepts of universal design but fuel for discrimination suits.

Functional Type II profiles have in fact been available for centuries. Although many common handrail profiles do not meet the Type II standard many do comply and are readily available. Today’s understanding of ergonomics today has proven that many objects designed to fit the hand in days of yore were well designed with little or no need of improvement. Such has been scientifically proven to be the case with many handrail profiles. It only makes sense to compound this knowledge with the ability to apply it through the use of a proven standard designers can utilize to develop and enhance the safety of the built environment for all people.

Image descriptions, clockwise

Grip of 2" round rail as in use on pitch. Note poor contact of thumb and void in of contact between thumb and first finger as well as need to twist thumb and fingers down to attain power grip. The power grip usually characterized at a right angle is very different when used on a pitched rail as is typical on stairs and ramps.
Grip on 1-3/4"h x2-5/8"w Type II rail in use on pitch. Note complete soft tissue contact and conformance of thumb with recess as well as readiness of stabilizing grip power-span grip. This contact is the reason for the exceptional longitudinal performance of Type II profiles.
Type II handrail in use keeps fingers away from supporting baluster and promotes compliant user readiness.

In Regard to the Safety of All

A graph composed by Jake Pauls from recent CPSC/NEISS 1974-2006 stairway accident data shared with the A117 committee shows a leveling or slight decrease in home accidents during the period from 2004–2006. Although this would correspond with the introduction of Type II rails in the building code, it is unlikely that this source has ever identified a citable accident or injury related to handrail shape and there is no correlation of NEISS data that could evidence warranting Type II or Type I handrails. Only a coincidence can be noted. The many variables affecting stairway accidents are well known. Only very dangerous assumptions like those that have historically restricted handrail shape can be made from such graphed data. We are better to rely on science to prove the hypothetical. Who would not rule out a common headache before submitting to brain surgery?

The advantages of Type II rails have been accepted for residential use since 2002 in the International Residential Code (IRC). In the 2006/2007 Code Development Hearing the IBC Means of Egress (MOE) committee recommended the addition of Type II rails to the IBC for all buildings. Conflict with the A117.1-2003 standard currently referenced by the IBC however ultimately lead to approval for only residential applications in the Final Action Hearing.

Familiarity of sustained successful use of Type II rails was not the only substantiation the ICC MOE Committee used in their decision. Extensive research and testing funded by the Stairway Manufacturers Association provided what was hailed as one of the most substantial studies ever brought to the code development process. The complete notated presentation as made to the A117 committee was shared with the MOE committee.

This testing and further research has been peer reviewed and on May 26, 2008 was accepted for publication in the respected peer review publication, "Applied Ergonomics" (publication date TBD). The testing provided new information pertaining to the shape of handrails and specifically determined what factors, related to certain shapes with recesses, could be used to define shapes that are equivalent in graspability to handrail shapes currently allowed in the A117.1 standard. Testing included: measuring the forces applied to a handrail in the induced falls of able bodied males; measuring the forces that could be applied to handrails in each of the primary directions to various handrail shapes by a wide population of individuals spanning age, sex, and hand size; correlation of these data across populations of varied height and weight by using computer modeling; statistical analysis of the probability of loss of grip. The results culminated in the Type II handrail definition and the accepted code language proposed for addition to the A117.1 standard.

It should be noted that handrail shape testing funded by others, performed by Brian Maki, and upon which the A117.1 based its prescriptive requirements

Excluded any shapes that qualify as Type II
Failed to disqualify any Type II shapes
Omitted all of the most common moulded profiled shapes designed and sold for specific use as handrails in wood or metal in North America.
Failed to determine what it is about a shape that makes it graspable
Tested only 20 adult subjects
Found a particular shape that worked well with one type of grip
Found a particular shape among the limited sample types that was subjectively preferred.
Measured only static pushing and pulling forces exerted by a restrained subject
Did not account for transverse forces
Normalized pushing and pulling forces based on an incorrect hypothesis of an inverted pendulum thereby exaggerating the upward element of the forces applied
Recognized the study’s limitations and called for further study prior to codification

New Opportunities

No research of the use of any handrails by persons with disabilities has been presented in the course of the history of the A117.1 standard. An intensive international literature review done in preparation of the article for "Applied Ergonomics" did not reveal any such work. We are still awaiting Mr. Jake Pauls' cited work from Australia, which he was invited to share with the A117 committee months ago.

The questions arise: Should this adoption of new technology with such apparent benefits of equivalent graspability and specific advantages over those handrails now allowed also be permitted without the specific testing of persons with disabilities? Are not the studies of the size, shape and grip size of a handrail relative to all users regardless of disability?

There will always be more to learn. Current A117.1 handrail requirements were adopted many years ago knowing very little compared to what we now specifically understand about handrail shape. Final acceptance of Type II handrails in the standard will provide to the universal design community; more functional handrail options, improved options for attachment and support, practical use of many other materials, lower fabrication costs, and provide new design freedom that will undoubtedly be the renaissance of many improvements to access and safety for all.

Your public comment in the A117 process could make a difference. For details go to: http://www.iccsafe.org/cs/standards/publicforms.html

David W. Cooper has more than 35 years of hands on experience within the stair industry. He is the principal of Stair Manufacturing and Design Consulting and represents the Stairway Manufacturers Association (SMA) in code and standard development. He can be contacted at coderep@stairways.org or dcooper@stairconsultants.com.

References:

Dusenberry, D.O., and Simpson, H. (2006). "Handrail Graspability," Presentation to the ICC/ANSI A117 Accredited Standard Committee July 2006 Meeting, Washington D.C.

Dusenberry, D.O., and Simpson, H. (1996). "Handrail Graspability," Engineering Mechanics Proceedings of the 11th Conference, American Society of Civil Engineers, New York, NY.

Dusenberry, D.O., Simpson, H., DelloRusso, S.J., and Rao, R.S. (1999). "Evaluation of Graspability of Handrails During Falls on Stairs." Engineering Mechanics Proceedings of the 14th Conference, American Society of Civil Engineers, Reston, VA.

Maki, B.E. (1985b). "Influence of handrail shape, size and surface texture on the ability of young and elderly users to generate stabilizing forces and moments." Report prepared under Contract No. OSR84-00197 for the National Research Council of Canada, Toronto, ON.

Maki, B.E., Perry, S.D (1996), "Influence of Handrail Design on Postural Stabilization: Pilot Phase." Report prepared for the Stairway Manufacturers Association under contract to Simpson Gumpertz and Heger, Inc.

Maki, B.E., Perry, S.D., and McIlroy, W.E. (1998). "Efficacy of Handrails in Preventing Stairway Falls: A New Experimental Approach," Safety Science, Apr. 1998, Vol. 28, No. 3, pp. 189 – 206.

Steinfeld, E. (1986). "Executive Summary," Hands-on Architecture. Volume 3, Part 1. Adaptive Environments Laboratory, Department of Architecture, SUNY/Buffalo, Dec.

Pauls, J. (1991a). "Are functional handrails within our grasp?" Building Standards, Jan/Feb, Vol. 60, No. 1, pp. 6 – 12.

Templer, J. (1992). The Staircase. The MIT Press, Cambridge, MA.