Design Traffic Loading Computation and Input Parameters in ESAL
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Questions and Answers

What does the reliability factor R% in pavement design represent?

  • The resilient modulus of the subgrade
  • The overall standard deviation
  • The probability that the pavement designed will not reach the terminal serviceability level before the end of the design period (correct)
  • The predicted traffic loading

    • What is the purpose of incorporating a reliability factor R% in pavement design?

  • To calculate the resilient modulus of the subgrade
  • To determine the effective roadbed soil
  • To account for uncertainties in traffic prediction and pavement performance (correct)
  • To establish the overall standard deviation

    • What does So represent in the context of flexible and rigid pavements?

  • Traffic loading distribution
  • Overall traffic loading
  • Standard deviation for flexible and rigid pavements (correct)
  • Resilient modulus of subgrade

    • Which functional classification requires the highest level of reliability according to AASHTO guidelines?

    <p>Interstates and other Freeways in urban areas</p> Signup and view all the answers

    Which parameter is used to determine the resilience of the subgrade in pavement design?

    <p>Resilient modulus of the subgrade</p> Signup and view all the answers

    What is recommended as the level of reliability for local roads in both urban and rural areas?

    <p>50 - 80%</p> Signup and view all the answers

    What is the initial serviceability index of the highway?

    <p>4.2</p> Signup and view all the answers

    What is the Marshall stability of the asphalt concrete surface layer?

    <p>1600 Ib</p> Signup and view all the answers

    What is the resilient modulus of the subgrade?

    <p>5 ksi</p> Signup and view all the answers

    What is the required subbase thickness if the thicknesses are not satisfactory?

    <p>7 in.</p> Signup and view all the answers

    What is the percentage that the pavement is exposed to saturation?

    <p>25%</p> Signup and view all the answers

    What is the reliability of the highway?

    <p>95%</p> Signup and view all the answers

    What is the elastic modulus of the surface course?

    <p>360,000 psi</p> Signup and view all the answers

    What is the terminal serviceability level of the pavement?

    <p>2.5</p> Signup and view all the answers

    What is the drainage coefficient of the base course?

    <p>1.20</p> Signup and view all the answers

    What is the value of a1 obtained from Fig. 5?

    <p>0.40</p> Signup and view all the answers

    What is the thickness of the subbase course (D3) rounded to the nearest whole number?

    <p>13.5 in.</p> Signup and view all the answers

    What is the total estimated traffic that the flexible pavement is designed to carry over the design period?

    <p>2.5 million ESAL</p> Signup and view all the answers

    What is the function of the total pavement thickness requirement?

    <p>Dependent on the resilient modulus of subgrade soil</p> Signup and view all the answers

    What is a common practice when laboratories are not equipped to perform the resilient modulus test for soils?

    <p>Estimate Mr through empirical correlation with other soil properties</p> Signup and view all the answers

    Which equation provides a correlation suggested by AASHTO for fine-grained soils with soaked CBR of 10 or less?

    <p>Equation (62.11)</p> Signup and view all the answers

    In computing the effective Mr, how does AASHTO suggest estimating relative damage corresponding to each seasonal modulus?

    <p>$\text{Relative damage} = \frac{Mr}{1000}$</p> Signup and view all the answers

    According to AASHTO, what is the purpose of an effective roadbed soil Mr?

    <p>To represent the combined effect of all seasonal modulus values</p> Signup and view all the answers

    What is the typical range of values for the regression constant K1?

    <p>1500-6000</p> Signup and view all the answers

    What is the first step suggested by AASHTO in computing the effective Mr?

    <p>Divide the year into equal-length time intervals</p> Signup and view all the answers

    How is the total structural number required above the subgrade soil, denoted SN3, determined?

    <p>Using the nomograph in Fig. 3 with Mr as input</p> Signup and view all the answers

    What is used to replace Mr to determine SN2?

    <p>E2 (stiffness modulus of base course material)</p> Signup and view all the answers

    What is used to replace Mr to determine SN1?

    <p>E3 (stiffness modulus of subbase material)</p> Signup and view all the answers

    What is the typical range of values for the regression constant K2?

    <p>0.4-0.6</p> Signup and view all the answers

    In Example 62.9, what is the design lane ESAL to be carried by the constructed pavement on the subgrade with Mr 5655psi?

    <p>5 x 10^6</p> Signup and view all the answers

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