The predicted traffic mix of a proposed four-lane urban non-interstate freeway is as follows. Passenger cars = 78% Single-unit trucks: 2-axle, 5,000 lb/axle = 12% 2-axle, 9,000 lb/axle = 4% 3-axle or more, 23,000 lb/axle = 3% Tractor semitrailers and combinations: 3-axle, 20,000 lb/axle = 3% The projected AADT during the first year of operation is 3,900 (both directions). If the traffic growth rate is estimated at 3 percent and the CBR of the subgrade is 7.5, determine the depth of a full-asphalt pavement (in inches) using the AASHTO method and n = 20 years. The resilient modulus of the asphalt (EAC) is 320,000 lb/in2. Assume mi for the subgrade is 1 and the percent of traffic on the design lane is 42 percent, pt = 2.5, and SN = 4. Use a reliability level of 90 percent, a standard deviation of 0.45, and a design serviceability loss of 2.0. Assume the design lane factor fd is 0.42. (Use single-axle load equivalency factors for 2-axle vehicles and tandem-axle load equivalency factors for 3-axle vehicles.)
The predicted traffic mix of a proposed four-lane urban non-interstate freeway is as follows.
Passenger cars = 78% Single-unit trucks: 2-axle, 5,000 lb/axle = 12% 2-axle, 9,000 lb/axle = 4% 3-axle or more, 23,000 lb/axle = 3% Tractor semitrailers and combinations: 3-axle, 20,000 lb/axle = 3%
The projected AADT during the first year of operation is 3,900 (both directions). If the traffic growth rate is estimated at 3 percent and the CBR of the subgrade is 7.5, determine the depth of a full-asphalt pavement (in inches) using the AASHTO method and
The resilient modulus of the asphalt
is 320,000 lb/in2. Assume
for the subgrade is 1 and the percent of traffic on the design lane is 42 percent,
and
Use a reliability level of 90 percent, a standard deviation of 0.45, and a design serviceability loss of 2.0. Assume the design lane factor
is 0.42. (Use single-axle load equivalency factors for 2-axle vehicles and tandem-axle load equivalency factors for 3-axle vehicles.)

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