Design Traffic Loading Computation and Input Parameters in ESAL

Play an AI-generated podcast conversation about this lesson

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?

Interstates and other Freeways in urban areas (D) Signup and view all the answers

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

Resilient modulus of the subgrade (A) Signup and view all the answers

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

50 - 80% (C) Signup and view all the answers

What is the initial serviceability index of the highway?

4.2 (D) Signup and view all the answers

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

1600 Ib (C) Signup and view all the answers

What is the resilient modulus of the subgrade?

5 ksi (D) Signup and view all the answers

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

7 in. (C) Signup and view all the answers

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

25% (A) Signup and view all the answers

What is the reliability of the highway?

95% (B) Signup and view all the answers

What is the elastic modulus of the surface course?

360,000 psi (B) Signup and view all the answers

What is the terminal serviceability level of the pavement?

2.5 (B) Signup and view all the answers

What is the drainage coefficient of the base course?

1.20 (A) Signup and view all the answers

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

0.40 (D) Signup and view all the answers

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

13.5 in. (B) Signup and view all the answers

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

2.5 million ESAL (B) Signup and view all the answers

What is the function of the total pavement thickness requirement?

Dependent on the resilient modulus of subgrade soil (D) Signup and view all the answers

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

Estimate Mr through empirical correlation with other soil properties (D) 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?

Equation (62.11) (C) Signup and view all the answers

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

$\text{Relative damage} = \frac{Mr}{1000}$ (B) Signup and view all the answers

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

To represent the combined effect of all seasonal modulus values (B) Signup and view all the answers

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

1500-6000 (C) Signup and view all the answers

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

Divide the year into equal-length time intervals (A) Signup and view all the answers

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

Using the nomograph in Fig. 3 with Mr as input (D) Signup and view all the answers

What is used to replace Mr to determine SN2?

E2 (stiffness modulus of base course material) (C) Signup and view all the answers

What is used to replace Mr to determine SN1?

E3 (stiffness modulus of subbase material) (A) Signup and view all the answers

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

0.4-0.6 (C) 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?

5 x 10^6 (A) Signup and view all the answers