The "Traction Index" Report
Title: ''The Traction Index - A New Method for
Measuring the Relative Slip Resistance of Footwear and
Objective: To establish a slip
resistance measuring technique which eliminates the
variability of the leather and rubber sensor pads when
measuring the SCOF of flooring and utilizes standard test
surfaces when measuring the SCOF of both footwear materials
and complete footwear and footwear sole and heel materials.
Method: Standard test surfaces are
used for standardizing the leather and rubber sensors in
order to calculate both the leather and rubber correction
factors when testing leather dry and a synthetic rubber
(Monarch EVA) both dry and wet. The ''standard SCOF'' of
leather is marked on the back of a polypropylene leather
(and synthetic leather) test panel. The ''standard SCOF"
Monarch EVA, both dry and wet (distilled water), is marked
on the back of the ASTM C1028 ceramic calibration tile.
These same surfaces are used to test complete footwear soles
and heels and footwear materials.
The complete shoe heel and sole, depending
on whether they are leather, synthetic leather or rubber, is
placed alternately on the polypropylene and ceramic tile
test surfaces. A 10-lb. weight is placed above the heel or
sole with a string loop, taped to the edge of the sole,
which is hooked to the force gage. A horizontal force is
applied to the string until the sole or heel starts to slip.
This force, divided by the weight of the shoe plus the
10-lb. weight, is the SCOF of the heel or sole. This SCOF,
divided by the ''standard scof" marked on the test panels,
is the ''Traction Index'' of the heel or sole. This compares
the footwear sole and heel materials to "standard
leather" and "standard rubber (EVA)".
This method is novel because the slip
resistance of any floor or floor coating, using leather and
rubber sensors, can be compared to the minimum SCOF required
for a slip-resistant floor by determining the ratio of the
measured SCOF to the minimum required SCOF. In this manner a
''Traction Index'' is calculated which provides a direct
indication of the slip resistance of the floor to ''standard
leather'' dry and ''standard rubber'' dry and wet. The
leather sensor is tested dry against polypropylene and the
rubber sensor (Monarch EVA) is tested dry and wet (distilled
water) against the ASTM C1028 ceramic calibration tile in
order to determine leather and rubber correction factors for
correcting the average SCOF of 8 onsite tests to
"standard leather" and "standard rubber
These same surfaces are then used to measure
the traction index of the heels and soles of complete
footwear. The footwear heel and sole traction indices are
the ratio of the measured SCOF to the standard SCOF of
''standard leather'' and ''standard rubber'' marked on the
back of the two test panels as previously stated.
This measuring technique permits forensic
engineers, who investigate slip/fall accidents, to determine
the traction index of both the floor at the accident site
and the victim's footwear. This test method permits both
flooring and footwear manufacturers to rate their products
based on the ''Traction Index''.
The flooring "Traction Index"
finally solves the problem of accurately measuring the slip
resistance of flooring, both dry and wet, with standardized
leather and rubber sensors. Valid measurements cannot be
obtained without standardizing the sensors.
The footwear (sole & heel)
"Traction Index" finally establishes standard test
surfaces for measuring leather type footwear materials dry
and rubber type footwear materials dry and wet.
This method makes every other slip
resistance test method obsolete i.e. ASTM flooring and
footwear test methods specified in VOSI V41.23X and VOSI
Donald Meserlian, P.E.,
VOSI Chairman Voices
of Safety International (VOSI)