Figure 16. Effect of pavement texture on skid resistance.

Fluid Pressure

Texture

Alleviation

Figure 15. Pavement surface charac-

3). However, it is important at all speeds and is a

vital component for overall skid resistance. Sec-

ond, the use of rounded coarse or fine aggregates

60

results in low skid resistance values (sample 2

5

and 4 in Figure 16).

Several laboratory tests are available to study

40

the change in macro- and microtextures under

3

repeated loading in the laboratory. Methods for

measuring texture can be categorized into volu-

20

4

metric, profile, topography, contact, drainage,

and miscellaneous measurements (Rose et al.

1

2

1972). Brief descriptions of some of the tests are

0

provided here. Details and references to these

0

20

40

60

80

and other devices can be found in Rose et al.

Speed, mph

(1972).

It must be realized that different test methods

1

Smooth

produce different results. It may not be possible

to correlate results from one test to another. The

2

Fine Textured, Rounded

most common test used today for determining

the macrotexture depth is the sand patch test,

3

Fine Textured, Gritty

described in the next subsection.

Volumetric measurements are commonly used

4

Coarse Textured, Rounded

for macrotexture depth determinations. These

include the sand patch, modified sand patch,

5

Coarse Textured, Gritty

vibrating sand patch, sand track, grease smear,

and silicone putty tests. These tests differ in the

Figure 16. Effect of pavement texture on skid

test materials and the patch geometry.

resistance.

11

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