Graduation Year


Document Type




Degree Granting Department

Civil and Environmental Engineering

Major Professor

Manjriker Gunaratne, Ph.D.

Co-Major Professor

Daniel Hess, Ph.D.

Committee Member

Gray Mullins, Ph.D.

Committee Member

Jian John Lu, Ph.D.

Committee Member

George Yanev, Ph.D.


Skid resistance, IFI, Roughness, Speed constant, Macrotexture


This dissertation is compiled of the findings of several phases of a detailed research study

that was aimed at investigating the Skid Resistance phenomenon.

In the first phase of the dissertation research a study was performed to evaluate the

different factors that influence frictional measurements obtained using the Dynamic

Friction Tester (DFT). A temperature calibration factor that would account for

temperature effects on DFT readings and IFI computations was developed. In addition,

other variables that also affect the friction measurements obtained using the DFT are


In the next phase of the dissertation research the effect of pavement roughness on the

Skid Resistance was investigated. The variation of the normal load and its nonlinear

relation to SN was used to explain lower SN values measured on relatively rougher

surfaces. The feasibility of using the International Roughness Index (IRI) and the

Dynamic Load Coefficient (DLC) as predictors of the reduction in SN due to pavement

roughness was also investigated.

In the final phase of the dissertation research an in-depth investigation was carried out to

better understand the principles underlying the concept of the International Friction Index

(IFI), and specifically the role played by the Speed Constant (

Sp) parameter in the IFI

computations. The parameter

Sp dictates the speed variation of the wet friction

measurements taken on a given pavement surface. The results of the current investigation

suggest the revision of the procedure for computation of the

Sp parameter to incorporate

device specific properties.

Furthermore, the incorporation of vehicle characteristics in the

Sp parameter

computations would help address a well known deficiency of the IFI, which is the


FR60 (predicted friction at 60 km/h) obtained from the friction values

measured at two different slip speeds on the same surface. This study also showed that

the modification of the

Sp parameter reduces significantly the slip speed dependency of

the device calibration parameters

A and B.

Finally, a modified IFI procedure that incorporates device specific slip conditions is

presented. The modified IFI procedure showed consistently better predictive capability

than the conventional ASTM procedure on all the different devices considered in this