by Geoff Fernie, PhD, PEng, CCE
Centre for Studies in Health and Aging,
Sunnybrook Hospital and Women's College Hospital
North York, Ontario
It would obviously be safer and easier if we all lived on one level
as we got older. This is not the reality and we are likely to have to
use some form of assistive technology to make the change in elevation
possible, less tiring or perhaps, simply less hazardous. For those
who are no longer able to climb stairs, options include the
installation of elevators and stair-climbing platforms. We will
address these in a later article.
The focus of this article is on how to specify and install handrails
that will reduce the risk of a falling accident as much as possible.
Good sturdy rails will also provide significant assistance for many
people in climbing the stairs.
The greatest dangers are of falling while descending the stairs.
Catching the heel on the edge of a tread (under stepping), missing a
step (overstepping) or simply losing balance may result in toppling
forward down the stairs. Note that a tread is the surface of a step,
whereas the vertical board is called the riser (i.e. each step
consists of a tread and a riser).
Studies in Dr. Brian Maki's
laboratory at the Centre for Studies in Aging at Sunnybrook & Women's College Health Sciences
Centre have recorded the sequence of actions that occurs when a person tries to recover from such
a falling incident on the stairs. It is very interesting to note that the hands start moving almost
immediately in the direction of the handrail.
Although the arm movement is reflexive, this targeting must be
preplanned since it occurs within approximately one-half the time
that would be required to initiate a voluntarily controlled movement.
Dr. Maki has hypothesized that, as we move around our environment,
the brain forms emergency plans and stores them such that they can
be recruited very rapidly, in a reflexive manner.
As the hand shoots out toward the rail, it is fully open, apparently
to increase the chances of contacting the rail. Typically, the palm
or the thumb contacts first and then the fingers flex quickly,
wrapping themselves around the rail. In order to arrest the fall, the
hand must generate substantial forces pulling along the axis of the
rail, pushing against the rail surface and pulling away from the
rail. It is, therefore, important that there be enough clearance
between the rail and the wall to allow for this free movement of the
fingers.
It is also important that the rail should be circular, or
near-circular in cross-section, so that the hands can grasp it firmly
and generate the required forces. Rails with different
cross-sectional forms, that do not allow the hand to grasp all the
way around, are much less adequate since they must rely on friction
generated by a pinch grip. Smaller diameter rails are also less
effective since they allow interference between the thumb and fingers
that may decrease the effectiveness of the grasp.
Some building codes emphasize the need to restrict the space between
the rail and the wall in order to avoid arms from becoming caught
between the two and being injured. In our view, a broken arm is the
lesser of potential evils, which include hip fractures and head
injuries.
Rails with different cross-sectional forms, that do not allow the
hand to grasp all the way around, are much less adequate since they
must rely on friction generated by a pinch grip.
Many rails are installed much too low and many building codes allow
minimum heights that are too low. It is really important to make
certain to install the handrail at an appropriately high height. In
order to explain why height is important, we must recall that the
term 'moment' means the turning effect of a force. For example, if we
use a short handle on a boat winch we must apply a lot more force to
tighten the sail than if we use a longer handle. This is because the
longer handle allows the sailor to generate a larger turning moment
on the winch for the same applied force. You may remember that the
size of a moment that is generated by a force is equal to the product
of the force and the length of the lever arm. Since many falls
involve rotating forwards or backwards, pivoting about a foot, rather
than simply crumpling downward, the rail is needed to allow the
faller to generate a moment that counteracts this falling rotation.
The higher the handrail the greater the moments that can be generated about
the faller's foot. The upper limit in height corresponds to the point at which people
begin to avoid reaching for the rail and
resting their hands on it as they descend. Obviously, it is better if
the rail is designed to encourage this activity so that the hand is
already in place when a fall occurs. For this reason, also, the
supports for the rail should be designed so as not to cause the user
to have to relax the grasp around the rail as the hand slides down.
The supports should, therefore, be slender and should be attached to
the bottom of the rail.
Falls often occur close to the top or the bottom of the stairs before
and after a steady rhythm is established. It is, therefore, important
to extend the rail at both the top and the bottom beyond the end of
the stairs and to curve it so that, if possible, it is parallel to
the level landing surfaces. This will also provide a tactile cue that
the end of the stairway is close.
The finishing of the rail is important. Dr. Barbara Cooper of
McMaster University discovered a safety yellow finish that is not
only more visible, but also apparently cues people to use it. One
might speculate that it helps people form their subconscious
emergency plan. If safety yellow is not acceptable, then, at least,
select a colour that contrasts with the wall.
The stairs should be appropriately lit and the tread surface should
be in good condition. Sometimes a contrasting colour strip is placed
along the nose of the stair, although studies have shown that a
contrasting coloured stripe running down either side of the stair may
be a more effective way of delineating the steps.
Unfortunately, there seem to be no good stair rail kits available on
the market. I have had to resort to going to a local welding shop to
have them make up an external rail from a 1.5" diameter steel tubing.
It is also hard to find appropriate and sturdy brackets that are
suitable for indoor stair rails.
In conclusion, a good stair handrail is 1.5" in diameter. It is
installed at a height of 36" above the nose of a step with 6"
clearance between the rail and the wall. The rail is continuous
around corners and continues at least 12" beyond the top and bottom
stair. It is attached sturdily using brackets that do not interfere
with the grasp of a hand sliding along the rail. The colour contrasts
with the wall and the stairs are lit avoiding strong shadows and
glare. Attention is also paid to the even spacing of the steps and
the condition of the tread surface. In order to get a good handrail,
you will probably either have to make one yourself or instruct a
contractor on how to make one. Fortunately, it is not a difficult
task for a typical welding or machine shop and should not cost more
than about $300 to $600, depending on the number of bends and the
length.
