(Solved): Question 3: The first year AADT on a six-lane freeway located in an urban area is expected to be 25 ...

Question 3: The first year AADT on a six-lane freeway located in an urban area is expected to be 25,000 veh/day. The growth rate for all the categories of vehicles is expected to be $2\%$ per annum throughout the life of the pavement. The design life of the pavement is 20 years and the projected vehicle mix during the first life of operation is: - Passenger cars $=50\%$ - Single-unit trucks, two-axle, four-tire $=28\%$ 16-Civ-A6 May 2019 Page 3 of 5 - Single-unit trucks, two-axle, six-tire $=18\%$ - Single-unit trucks, six-axle or more $=4\%$ a) Determine the design ESAL for the service life of the pavement. b) Design the flexible pavement to carry this design ESAL based on the following information: - The effective resilient modulus of the subgrade $\mathrm{Mr}=10,000\mathrm{psi}$. - The subbase layer is an untreated silty sand with a resilient modulus (ESB) of 18,000 psi. - The base layer is an untreated granular material with a resilient modulus ( ${\mathrm{E}}_{\mathrm{B}}$ ) of $30,000\mathrm{psi}$. - The elastic modulus of the asphalt concrete at $20^{?}\mathrm{C}\left({\mathrm{E}}_{\mathrm{AC}}\right)$ is $450,000\mathrm{psi}$. - The pavement structure will be exposed to moisture levels approaching saturation $15\%$ of the time and it would take about 1 day to drain the water. - The use of modern pavers allows the achieving of high level of serviceability values after the construction $\left({\mathrm{p}}_0=4.5\right)$ and the lowest acceptable value of the serviceability index is 2.5 . - The overall standard deviation is 0.5 and the required level of reliability is $90\%$