Pavement friction have become a characteristic of interest due to its impact on road safety. The demand of the transportation agencies for equipment to measure the friction of their pavements grew. Different companies developed in parallel way different devices to satisfy that demand. This generate that the different transportation agencies are using different devices to measure the same characteristic. In order to determine a threshold for the adequate friction levels, the need to compare those data was created. Several attempts to harmonize those measurements have been developed, but have demonstrate that not produce harmonious results among some devices. Also, there are new equipment like the Continuous Friction Measurement Equipment (CFME) that offer some advantages compared to the traditional Locked Wheel Trailer (LWST) that also generate the need to compare historical data to the collected with the new device. This thesis is proposing an interconversion method between the measurements from a CFME as the SCRIM and the LWST. / Master of Science / This thesis compares two devices that measure the friction of the pavement surface. One of the devices, the Locked Wheel Skid Tester (LWST) is the one that have traditionally used for the Departments of Transportation (DOT) in the US. The other one is a newer technology that is able to measure the friction in a continuous way (SCRIM). The comparison of measurement is difficult because there are many factors that affect the tire-pavement friction. The International Friction Index (IFI) provides a comparison approach but require taking static reference measurements that are time consuming and require road closures. This thesis proposes a simplified method to convert measurements with the LWST using only the SCRIM that do not require these reference measurements.

State highway agencies have an obligation to provide users with optimal surface conditions under various weather conditions throughout the year. A satisfactory pavement surface should exhibit good friction and texture depth to reduce roadway highway accidents. This is why friction is starting to receive increased attention in the pavement management process. There have been numerous research efforts by different countries and agencies to better understand the behavior of different friction testing devices and the influence of texture, speed, and other external conditions on their measurements. The first part of this thesis presents a research effort to compare and harmonize texture and skid resistance measurements taken with various devices on 24 pavement sections with a wide range of textures. Measurements were compared and the International Friction Index (IFI) calculated following PIARC and ASTM steps. The results revealed discrepancies in the IFI values calculated for the different devices, suggesting that the coefficients A, B, and C proposed by PIARC may need to be adjusted for each device considered before the IFI can be implemented by the surface properties consortium participating agencies. In this research the A, B, and C coefficients were then recalculated, and the predicted values of friction using these revised coefficients are presented. The coefficients developed were also used to obtain IFI values for high-friction surfaces (HFS). It has been found that under different conditions, different parameters and coefficients will result. It is strongly recommended equipment comparison experiments (like the NASA and Smart Road programs) continue to better determine the coefficients necessary for harmonization. HFS have emerged as viable high-friction pavement alternatives that mitigate the consequences of driver error, poor geometric alignment of the roadway, and insufficient friction at the tire-pavement interaction, especially during wet weather. This thesis presents a study of the HFS available in the U.S. market and their performance (friction and texture) in different applications, under different weather conditions, and in various locations. This thesis also presents the results of the benefit-cost analysis for the studied HFS. / Master of Science

A caracterização da macrotextura e microtextura da superfície de pavimentos asfálticos pode ser obtida por meio de diversos tipos de equipamentos que possuem características distintas. Os resultados dos ensaios obtidos por esses diferentes equipamentos foram comparados e harmonizados por uma grande pesquisa desenvolvida pela PIARC (Permanent International Association of Road Congress, atualmente denominada de World Road Association) que converteu estes diferentes valores em um índice internacional combinado denominado de IFI - International Friction Index. Posteriormente, a ASTM especificou o emprego deste índice por meio da publicação da norma E 1960-98 Standard Practice for Calculating International Friction Index of a Pavement Surface. Nesta tese foram avaliados a textura e o atrito em doze tipos de revestimentos asfálticos com características distintas: usinados a quente de diversas graduações, tratamentos superficiais, microrrevestimentos a frio e lamas asfálticas, por meio de aparelhagem portátil: ensaios de mancha de areia e Pêndulo Britânico, respectivamente. Estes diferentes revestimentos apresentam uma gama de textura variando de aberta e rugosa a fechada e polida. Os resultados geraram um banco de dados com 417 valores de campo, sendo 178 referentes à macrotextura, 166 à microtextura e 73 à drenabilidade. Com estes dados, foram calculados valores de IFI, compostos pelos parâmetros Sp e F60, resultando em 165 pares de valores. Com base na experiência prática e análises estatísticas, demonstrou-se a validade de uso de equipamentos portáveis para a determinação dos valores de IFI e estabeleceram-se critérios e faixas de classificação para a aderência em função do par de valores de IFI (Sp; F60). Esta classificação possibilita os órgãos viários a usarem o IFI (Sp; F60) como uma ferramenta de gerência de pavimentos para avaliarem as condições de aderência em pista molhada de suas vias ou de locais específicos, objetivando, quando necessária, a realização de intervenções. / The characterization of the macrotexture and microtexture of asphalt pavements surfaces can be obtained by means of different types of equipment presenting different characteristics. The results of the essays obtained by these different equipment were compared and harmonized by an ample research developed by PIARC (Permanent International Association of Road Congress, now denominated World Road Association) which converts these different values into an international combined index denominated IFI - International Friction Index. Later, the ASTM specified the employment of this index by publishing norm E 1960-98 Standard Practice for Calculating International Friction Index of a Pavement Surface. In this thesis, texture and friction were evaluated on twelve types of asphalt pavings with different characteristics: hot asphalt mixes of different gradations, asphalt surface treatments, cold-mixed micro-surfacing and slurry seals, by means of portable equipment, sand patch and British pendulum essays, respectively. These different pavings present a range of texture varying from open and rough to closed and polished. The results generated a database with 417 field values, being 178 related to macrotexture, 166 to microtexture and 73 to drainability. With these data, IFI values were calculated, composed by parameters Sp and F60, resulting in 165 pairs of values. Based on practical experience and on statistical analyses, the validity of using portable equipment for determining the IFI values was demonstrated and classification criteria and bands for adherence were established in function of the pair of IFI values (Sp; F60). This classification allows road organisms to use IFI (Sp; F60) as a pavement management tool to assess the adherence conditions on the wet lanes of their roads or on specific sites, aiming to conduct interventions, whenever necessary.

A caracterização da macrotextura e microtextura da superfície de pavimentos asfálticos pode ser obtida por meio de diversos tipos de equipamentos que possuem características distintas. Os resultados dos ensaios obtidos por esses diferentes equipamentos foram comparados e harmonizados por uma grande pesquisa desenvolvida pela PIARC (Permanent International Association of Road Congress, atualmente denominada de World Road Association) que converteu estes diferentes valores em um índice internacional combinado denominado de IFI - International Friction Index. Posteriormente, a ASTM especificou o emprego deste índice por meio da publicação da norma E 1960-98 Standard Practice for Calculating International Friction Index of a Pavement Surface. Nesta tese foram avaliados a textura e o atrito em doze tipos de revestimentos asfálticos com características distintas: usinados a quente de diversas graduações, tratamentos superficiais, microrrevestimentos a frio e lamas asfálticas, por meio de aparelhagem portátil: ensaios de mancha de areia e Pêndulo Britânico, respectivamente. Estes diferentes revestimentos apresentam uma gama de textura variando de aberta e rugosa a fechada e polida. Os resultados geraram um banco de dados com 417 valores de campo, sendo 178 referentes à macrotextura, 166 à microtextura e 73 à drenabilidade. Com estes dados, foram calculados valores de IFI, compostos pelos parâmetros Sp e F60, resultando em 165 pares de valores. Com base na experiência prática e análises estatísticas, demonstrou-se a validade de uso de equipamentos portáveis para a determinação dos valores de IFI e estabeleceram-se critérios e faixas de classificação para a aderência em função do par de valores de IFI (Sp; F60). Esta classificação possibilita os órgãos viários a usarem o IFI (Sp; F60) como uma ferramenta de gerência de pavimentos para avaliarem as condições de aderência em pista molhada de suas vias ou de locais específicos, objetivando, quando necessária, a realização de intervenções. / The characterization of the macrotexture and microtexture of asphalt pavements surfaces can be obtained by means of different types of equipment presenting different characteristics. The results of the essays obtained by these different equipment were compared and harmonized by an ample research developed by PIARC (Permanent International Association of Road Congress, now denominated World Road Association) which converts these different values into an international combined index denominated IFI - International Friction Index. Later, the ASTM specified the employment of this index by publishing norm E 1960-98 Standard Practice for Calculating International Friction Index of a Pavement Surface. In this thesis, texture and friction were evaluated on twelve types of asphalt pavings with different characteristics: hot asphalt mixes of different gradations, asphalt surface treatments, cold-mixed micro-surfacing and slurry seals, by means of portable equipment, sand patch and British pendulum essays, respectively. These different pavings present a range of texture varying from open and rough to closed and polished. The results generated a database with 417 field values, being 178 related to macrotexture, 166 to microtexture and 73 to drainability. With these data, IFI values were calculated, composed by parameters Sp and F60, resulting in 165 pairs of values. Based on practical experience and on statistical analyses, the validity of using portable equipment for determining the IFI values was demonstrated and classification criteria and bands for adherence were established in function of the pair of IFI values (Sp; F60). This classification allows road organisms to use IFI (Sp; F60) as a pavement management tool to assess the adherence conditions on the wet lanes of their roads or on specific sites, aiming to conduct interventions, whenever necessary.