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17.1 Introduction
Flexible pavement is a structure designed for a certain period known as design life
to resist traffic and environment. The structure is designed to safeguard the subgrade
and maintain safety and cost of operation within a reasonable limit. The fundamental
inputs for designing the pavement include the strength of the subgrade, environmental
conditions, strength of the layer materials and the predicted traffic load (McElvaney
and Snaith 2012). The pavements could be designed by many different empirical
procedures, even though they are convenient to use, research proved that, some of
these methods provide undesirable results. This major drawback of the procedures
has led to the development of mechanistic procedures over the last 40 years (Allen
et al. 2015).
Many comparative studies were conducted to compare the different flexible pavement design procedures. For example, Yahya et al. compares cost of flexible pavement in Nigeria designed using the contemporary methods and found CBR method
to be cost effective (Yahaya et al. 2018). Saha et al. 2012 compares the American
association of state highway and transportation officials (AASHTO) mechanistic
empirical design guide (MEPDG) and the Alberta transportation flexible pavement
design procedure. It was found that, when using the MEPDG, only the cases with a
strong subgrade material and a low level of traffic meet the default limit value for total
pavement rutting. El-Badawy et al. (2011) also compares Idaho Pavement Design
Procedure with AASHTO 1993 and MEPDG Methods. The findings shows that, the
Idaho pavement design method overestimates the pavement thickness in comparison to the AASHTO 1993 and MEPDG. Chidozie and Joshua (2016) compared the
traffic loading obtained using the Road Note 29, HD 26/01, and LR1132 procedures
for designing flexible pavement. Perraton et al. (2010) made a comparison between
pavement design methods from a fatigue point of view.
In this paper a comparative analysis of some flexible pavement design methods was
done using fuzzy preference ranking organization method for enrichment evaluations
(PROMETHEE) technique to identify the best method to be used for design flexible
pavement considering multiple criteria.
17.2 Flexible Pavement Design Method
17.2.1 Asphalt Institute Method
Multi-layered elastic system is used to represent the pavement structure in the Asphalt
Institute design method. The load from the traffic is applied as a uniform vertical
stress through the tire which is spread by the different pavement layers and finally
to the subgrade as a lower stress. Established theories, experience and test results
are applied to determine the two stress–strain situations. Firstly, the change of the
stress through the pavement layer and secondly the tensile and compressive stresses
and strains imposed on the asphalt due to the deflection caused by wheel loads. The
I. K. Umar et al.
17.1 Introduction
Flexible pavement is a structure designed for a certain period known as design life
to resist traffic and environment. The structure is designed to safeguard the subgrade
and maintain safety and cost of operation within a reasonable limit. The fundamental
inputs for designing the pavement include the strength of the subgrade, environmental
conditions, strength of the layer materials and the predicted traffic load (McElvaney
and Snaith 2012). The pavements could be designed by many different empirical
procedures, even though they are convenient to use, research proved that, some of
these methods provide undesirable results. This major drawback of the procedures
has led to the development of mechanistic procedures over the last 40 years (Allen
et al. 2015).
Many comparative studies were conducted to compare the different flexible pavement design procedures. For example, Yahya et al. compares cost of flexible pavement in Nigeria designed using the contemporary methods and found CBR method
to be cost effective (Yahaya et al. 2018). Saha et al. 2012 compares the American
association of state highway and transportation officials (AASHTO) mechanistic
empirical design guide (MEPDG) and the Alberta transportation flexible pavement
design procedure. It was found that, when using the MEPDG, only the cases with a
strong subgrade material and a low level of traffic meet the default limit value for total
pavement rutting. El-Badawy et al. (2011) also compares Idaho Pavement Design
Procedure with AASHTO 1993 and MEPDG Methods. The findings shows that, the
Idaho pavement design method overestimates the pavement thickness in comparison to the AASHTO 1993 and MEPDG. Chidozie and Joshua (2016) compared the
traffic loading obtained using the Road Note 29, HD 26/01, and LR1132 procedures
for designing flexible pavement. Perraton et al. (2010) made a comparison between
pavement design methods from a fatigue point of view.
In this paper a comparative analysis of some flexible pavement design methods was
done using fuzzy preference ranking organization method for enrichment evaluations
(PROMETHEE) technique to identify the best method to be used for design flexible
pavement considering multiple criteria.
17.2 Flexible Pavement Design Method
17.2.1 Asphalt Institute Method
Multi-layered elastic system is used to represent the pavement structure in the Asphalt
Institute design method. The load from the traffic is applied as a uniform vertical
stress through the tire which is spread by the different pavement layers and finally
to the subgrade as a lower stress. Established theories, experience and test results
are applied to determine the two stress–strain situations. Firstly, the change of the
stress through the pavement layer and secondly the tensile and compressive stresses
and strains imposed on the asphalt due to the deflection caused by wheel loads. The