-This test needs traffic control and lane closure.

-It does not always simulate pavement?tire characteristics.

-It cannot be used for network evaluation because of its spot measurement.

-This test is highly repeatabile and reproducibile and is unaffected by operators procedure or wind.

-Results of this method produce friction coefficients that are representative of high speed values.

-The IFI statistics have good correlate with BPN.

The Dynamic Friction Tester (DFT) produces these indices:

-DFT numbers or friction coefficients

-Peak friction

-Associated peak slip speed -International Friction Index (IFI), designated by F(60) and SP.

This device also presents the graph of the friction coefficient for different rotational speeds.

ASTM E1911

Dynamic friction test

-It’s a hard method which has poor Repeatability.

-Method is time consuming and requires traffic control and lane closure.

-Results of this test Only represent characteristics of macro-texture of a small area.

-It is sensitive to operator procedure.

-It is a simple and low cost method and its equipment are inexpensive.

-It’s a widespread method.

-A combination of this test’s results with other data can provide friction information.

It measures the sample volume and average diameter of materials and mean texture depth is computed as:

where:

MTD = Mean texture depth, in (mm)

V = Sample volume(mm³)

D = Average material diameter (mm)

ASTM E 965,

ISO10844

Sand patch

-This test can be used only for non-porous surfaces.

-The method is slow and requires traffic control and lane closure.

-Results of this test only represent characteristics of a small surface area.

-Its results have a low correlation with MPD or MTD

-It is a simple method and its equipment is relatively inexpensive.

-Its results are an indication of hydroplaning potential in wet weather conditions.

It measures the time in milliseconds for outflow of specified volume of water called Outflow time (OFT). Shorter outflow time means rougher surface texture.

ASTM E380 FHWA

Outflow test

-The method is a little slow.

-Requires lane closure and traffic control.

-Only represents characteristics of a small surface area.

-This method is repeatable and reproducible and it has portable equipment.

-It is possible to measure the same diameter as DFT, for texture?friction comparisons.

-It is insensitive to operators’ procedure.

-Its output correlates well with MTD.

-Its setup time is quite short.

CTM provides these indices:

-Mean profile depth (MPD) -Root mean square (RMS)

ASTM E2157

Circular texture meter

-It only has the ability of measuring the texture of aggregates.

-It needs large data storage capacity.

-It is non-contact and very high-speed.

-It provides detailed information on all sizes of paving aggregates.

Indices provided by the AIMS include the estimated texture depth (ETD).

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AIMS