-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). | - | AIMS |