The KDOT （Kansas Department of Transportation） is currently adopting MEPDG （mechanistic-empirical pavement design guide） to replace the 1993 AASHTO （American Association of State Highway and Transportation Offici...The KDOT （Kansas Department of Transportation） is currently adopting MEPDG （mechanistic-empirical pavement design guide） to replace the 1993 AASHTO （American Association of State Highway and Transportation Officials） design method. The main objective of this study was to compare flexible pavement design using 1993 AASHTO design guide and MEPDG. Five newly built Superior PERforming Asphalt PAVEments （Superpave）, designed using the 1993 AASHTO Design Guide, were selected as test sections for the design simulation study. Deflection data were collected approximately 8 to 10 weeks after construction using FWD （falling weight deflectometer）. The FWD deflection data were used to back-calculate the pavement layer moduli using three different back-calculation programs. The existing pavement structures were analyzed for a 10-year analysis period. The maximum numbers of years the existing pavement structures will be in a serviceable condition as well as the minimum thicknesses of different layers to serve for 10-years were also determined. Effects of changing subgrade modulus, target distress, and reliability were also investigated. The MEPDG design analysis shows that the 1993 AASHTO Guide-designed flexible pavements do not show the distresses currently observed in Kansas for the 10-year design period. The MEPDG design simulation shows that the thinner the pavement sections, the higher the permanent deformation. The existing pavement structures can serve for more than 20 years as per the MEPDG design analysis if the default failure criteria and nationally-calibrated models are used.展开更多
Service life is often used by state transportation agencies to evaluate alternative flexible pavement designs.The design that keeps the pavement in acceptable condition longest before it needs another maintenance trea...Service life is often used by state transportation agencies to evaluate alternative flexible pavement designs.The design that keeps the pavement in acceptable condition longest before it needs another maintenance treatment is the preferred design.For a given rehabilitation design,this study evaluates the pavement service life using AASHTO 1972 pavement design guide and mechanistic-empirical(M-E)pavement design guide.The service life here is referred as the duration from last completed rehabilitation to the next maintenance treatment.The goal is not to determine which method is better,but rather,it is to understand how their estimated service lives differ and what factors contribute to their differences.To perform the evaluation,rehabilitation designs developed by the SCDOT for a research project are used.These designs take into account existing pavement distresses obtained through field investigation of 28 actual rehabilitation projects on primary routes.Service life is determined using MAP-21 criteria for good and fair pavements.Analysis results indicated that(1)the predicted service life using the M-E method has lower variation than the AASHTO 1972 method and is affected by the location(rural vs.urban)of the routes,(2)the predicted service life using the AASHTO 1972 method is generally lower than that of the M-E method and is affected by the difference between the design structural number(SN)and required SN,(3)the M-E service life for good pavement is generally longer for routes that include CMRB design and the percentage of trucks lower than 10%,and(4)the AASHTO 1972 service life is higher if the existing SN is already exceeding the required SN from the previous maintenance.展开更多
文摘The KDOT （Kansas Department of Transportation） is currently adopting MEPDG （mechanistic-empirical pavement design guide） to replace the 1993 AASHTO （American Association of State Highway and Transportation Officials） design method. The main objective of this study was to compare flexible pavement design using 1993 AASHTO design guide and MEPDG. Five newly built Superior PERforming Asphalt PAVEments （Superpave）, designed using the 1993 AASHTO Design Guide, were selected as test sections for the design simulation study. Deflection data were collected approximately 8 to 10 weeks after construction using FWD （falling weight deflectometer）. The FWD deflection data were used to back-calculate the pavement layer moduli using three different back-calculation programs. The existing pavement structures were analyzed for a 10-year analysis period. The maximum numbers of years the existing pavement structures will be in a serviceable condition as well as the minimum thicknesses of different layers to serve for 10-years were also determined. Effects of changing subgrade modulus, target distress, and reliability were also investigated. The MEPDG design analysis shows that the 1993 AASHTO Guide-designed flexible pavements do not show the distresses currently observed in Kansas for the 10-year design period. The MEPDG design simulation shows that the thinner the pavement sections, the higher the permanent deformation. The existing pavement structures can serve for more than 20 years as per the MEPDG design analysis if the default failure criteria and nationally-calibrated models are used.
文摘Service life is often used by state transportation agencies to evaluate alternative flexible pavement designs.The design that keeps the pavement in acceptable condition longest before it needs another maintenance treatment is the preferred design.For a given rehabilitation design,this study evaluates the pavement service life using AASHTO 1972 pavement design guide and mechanistic-empirical(M-E)pavement design guide.The service life here is referred as the duration from last completed rehabilitation to the next maintenance treatment.The goal is not to determine which method is better,but rather,it is to understand how their estimated service lives differ and what factors contribute to their differences.To perform the evaluation,rehabilitation designs developed by the SCDOT for a research project are used.These designs take into account existing pavement distresses obtained through field investigation of 28 actual rehabilitation projects on primary routes.Service life is determined using MAP-21 criteria for good and fair pavements.Analysis results indicated that(1)the predicted service life using the M-E method has lower variation than the AASHTO 1972 method and is affected by the location(rural vs.urban)of the routes,(2)the predicted service life using the AASHTO 1972 method is generally lower than that of the M-E method and is affected by the difference between the design structural number(SN)and required SN,(3)the M-E service life for good pavement is generally longer for routes that include CMRB design and the percentage of trucks lower than 10%,and(4)the AASHTO 1972 service life is higher if the existing SN is already exceeding the required SN from the previous maintenance.
