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SOTTER ENGINEERING CORPORATION Consultants

26705 Loma Verde, Mission Viejo, CA 92691-6055

Telephone/FAX: 949-582-0889

July 13, 2012 Mr. Robert Randolph Soil Stabilization Products Co., Inc. PO Box 2779 Merced, CA 95344 SUBJECT: Field testing of NaturalPAVE XL Resin Pavement in situ at Buena Vista Park and McCoppin Square Park in the City and County of San Francisco Dear Mr. Randolph: On July 9, 2012 Sotter Engineering Corporation assessed the pedestrian slip resistance potential of and also performed the ASTM C1028-07 test on NaturalPAVE XL Resin Pavement at the Buena Vista Park and McCoppin Square Park in the City and County of San Francisco. We also tested broomed finish concrete and asphalt installations. The Buena Vista Park is located at the corner of Haight Street and Buena Vista Avenue East, San Francisco. City and County of San Francisco staff observing the ASTM C 1028 and Pendulum testing of the NaturalPAVE XL Resin Pavement installation at Buena Vista Park, and of the broomed finish Portland Cement Concrete pavement across the street from the park were: John Paul Scott and Jim Whipple from the Mayor's Office on Disability; Kevin Jensen, Disability Access Coordinator for the Department of Public Works; and Koa Pickering, Landscape Architect, Recreation and Parks Department. McCoppin Square Park is located at 1300 Taraval Street, San Francisco. City and County of San Francisco staff observing the ASTM C 1028 and Pendulum testing of the NaturalPAVE XL Resin Pavement and Hot Mix Asphalt installations at McCoppin Square Park were: Kevin Jensen, Disability Access Coordinator for the Department of Public Works, and Koa Pickering, Landscape Architect, Recreation and Parks Department.

Licensed by the State of California Board for Professional Engineers and Land Surveyors Approved by City of Los Angeles for testing slip resistance

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Test methods. We tested the various areas using the pendulum method for slip resistance and the ASTM

C1028-07 for static coefficient of friction.

Pendulum tester. We consider the pendulum to be the primary standard for pedestrian slip

resistance, as recommended since 2001 by Ceramic Tile Institute of America (ctioa.org,

Test Report #1: Portable Methods). Figures 1 and 2 show the pendulum.

Figure 1. Pendulum tester, endorsed by Ceramic Tile Institute of America (CTIOA)

Figure 2. The trailing edge of the pendulum’s three-inch-wide slider (left) slides to left

along the floor, where friction prevents the pointer (right) from returning to zero

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The test method is based on American Society for Testing and Materials Standard E 303.

The pendulum device is a national standard for pedestrian slip resistance testing in at

least 49 nations on four continents, which makes it by far the most-accepted method

worldwide. Decades of extensive research into slip and fall accidents using the pendulum

test method in the United Kingdom, Australia and New Zealand has led to the present

safety standards, which are endorsed by the CTIOA.

ASTM C1028-07 Static Coefficient of Friction test method. In the C1028-07 static

coefficient of friction test, the operator pulls on a 50 pound weight that is placed on top of

a slider assembly, which has Neolite rubber contacting the floor. The operator attempts to

pull smoothly on a dynamometer until the slider assembly and weight go into motion.

The amount of pounds force recorded on the dynamometer is then recorded.

The Americans with Disabilities Act (ADA) requires that accessible floors be “slip-

resistant,” but does not define what that means. American Society for Testing and

Materials (ASTM) has established that its method C 1028, Static Coefficient of Friction,

is not adequate for assessing pedestrian safety. Tile Council of North America, CTIOA,

University of Southern California Medical Center, and Sotter Engineering Corporation

concur. “Safe” readings are too often obtained on dangerously slippery surfaces, and the

test does not evaluate hydroplaning potential, a common cause of slip and fall accidents.

Please see www.C1028.info for information on this obsolete test method. The test was

done at the request of the City and County of San Francisco officials, and a

demonstration was performed showing how this test method gives misleading results. We

believe the use of this test method in assessing pedestrian slip resistance is fraudulent.

Figure 3. C1028-07 test in action. A 50 pound weight on top of a slider assembly with

Neolite rubber contacting the floor is pulled by the operator. The pulling is done with a

dynamometer, which records the force required to set the assembly and weight in motion.

Sotter Engineering Corporation does NOT recommend using this test for assessing

pedestrian slip resistance. This test often gives misleading results.

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Test results

Table 1 shows the test data, safety criterion, and associated assessment of slip potential

for each test. Results apply only to the samples tested.

Instrument Measurand

Threshold

value

Test

result

Slip

potential

Pendulum Pendulum Test Value PTV

Buena Vista, NaturalPAVE Four S hard rubber, dry 63 Low

wet 52 Low

Buena Vista, broomed concrete Four S hard rubber, dry 67 Low

wet 60 Low

McCoppin, NaturalPAVE Four S hard rubber, dry 70 Low

wet 62 Low

McCoppin, asphalt wet 60 Low

C1028-07 Static Coefficient of Friction

Buena Vista, NaturalPAVE Neolite rubber, dry 0.85 ?

wet 0.83 ?

Buena Vista, broomed concrete Neolite rubber, dry 1.01 ?

wet 0.99 ?

McCoppin, NaturalPAVE Neolite rubber, dry 0.98 ?

wet 0.88 ?

McCoppin, asphalt Neolite rubber, dry 0.88 ?

wet 0.87 ?

Unknown

36

Table 1. Safety criterion and test data

In addition to test data the table shows a “threshold value,” which is the normal minimum

safety criterion used for Pendulum Test Value. The C1028 test does not have a threshold

value, and is therefore of little use in assessing safety of moving pedestrians.

While the usual PTV safety criterion is 36, more detailed safety standards for the

Pendulum Test Value from Ceramic Tile Institute of America (ctioa.org) are

PTV Slip potential

0–24 High

25-35 Moderate

36 and higher Low

The PTVs of all surfaces tested were well into the “low slip potential” regime. The PTVs

of NaturalPAVE were slightly above those of asphalt measured at McCoppin Park, and

slightly below that of broomed concrete measured at Buena Vista Park.

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Conclusion

All the test data showed low slip potential. We find no results of concern regarding initial

slip resistance hazard for the surfaces tested for this report. NaturalPAVE has a PTV that

lies between those of asphalt and broomed concrete, both of which are considered to be

safe in regards to slip resistance.

Should you require any further assistance, information or clarification, please contact our

office. We appreciate the opportunity to provide this service.

Respectfully submitted,

SOTTER ENGINEERING CORPORATION

J. George Sotter, P.E., Ph.D.

President