Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 19, Problem 14P
To determine
The design of a flexible pavement using the 1993 AASHTO procedure.
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Q2: The traffic on the design lane of a proposed four-lane rural interstate highway consists of 40% trucks. If classification studies have shown that the truck factor can be taken as 0.45, design a suitable flexible pavement using the 1993 AASHTO procedure if the AADT on the design lane during the first year of operation is 1150, pi = 4.5, and pt = 2.5 .
Growth rate = 3%
Design life = 20 years
Reliability level = 95%
Standard deviation = 0.45
The pavement structure will be exposed to moisture levels approaching saturation 20% of the time, and it will take about one week for drainage of water.
Effective CBR of the subgrade material is 7. CBR of the base and subbase are 70 and 22, respectively, and Mr for the asphalt mixture, 3102 MPa (450,000 lb/in2).
The traffic on the design lane of a proposed four-lane rural interstate highway consists of 40 percent trucks. If classification studies have shown that the truck factor can be taken as 0.45, design a suitable flexible pavement if the Average Annual Daily Traffic (AADT) on the design lane during the first year of operation is 1000, initial serviceability (Po) = 4.4, and terminal serviceability (Pt) = 2.5.
Growth rate = 4 percent Design life = 20 years Reliability level = 95 percent
The pavement structure will be exposed to moisture levels approaching saturation 20 percent of the time, and will take about one week for drainage of water. California Bearing Ratio (CBR) of the subgrade material is 7. CBR of the base and subbase are 70 and 22 respectively, and Resilient Modulus (Mr) for asphalt concrete is 450,000 lb/in2.
A pavement was designed to have 50 mm bituminous surface course, bituminous
binder course 190 mm, 200 mm crushed aggregate road base, and 150 mm granular
subbase. The designed was based on the number of ESALs for the base year is 1.4
million, design period is 20 years and average annual traffic growth factor is 4.5%.
Using these data:
Determine the Subgrade modulus design input value and Estimate the design traffic (ESAL DES).
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- A flexible pavement is constructed with 4 inches of hot-mix asphalt wearing surface, 10 inches soil cement base and 10 inches crushed stone subbase. The subgrade has a soil resilient modulus of 12,000 lb/in2, M2 = 1.5 and M3=1.127 for the materials of the pavement structure. The overall standard deviation is 0.5, the initial PSI = 5.0 and the terminal serviceability index (TSI) is 2.5. The daily traffic has 3000 cars, 1000 trucks and 500 trailers. The axle weights are: How long in years would the pavement last if R = 98% ? (Final answer to 2 decimal places)arrow_forwardThe AADTT of a 2-way (2-lane each way) highway is 10,000. The directional distribution may vary between 45 and 55% depending on season. The lane distribution may vary between 60 and 75%. The driving lane always carries more loads compared to the passing lane. The growth factor for the pavement is 3.5%. Based on the above information, calculate the design AADTT for the driving lane if the pavement service life is 20 years.arrow_forwardA flexible pavement has a structural number of 3.8 (all drainage coefficients are equal to 1.0). The initial PSI is 4.7 and the terminal serviceability is 2.5. The soil has a CBR of 9. The overall standard deviation is 0.40 and the reliability is 95%. The pavement is currently designed for 1800 equivalent 18-kip single-axle loads per day. If the number of 18-kip single-axle loads were to increase by 30%, by how many years would the pavement design life be reduced?arrow_forward
- 12. Refer to Figure II-1 attached. A flexible pavement is to be evaluated according to the AASHTO 1972 design guide. The existing pavement has a weighted structural number=3.4, a regional factor=2.0, and a soil support value=4.5. What would be the approximated number of daily equivalent 18-kip axles to be allowed on this road for a 20-year analysis period?a. 10b. 33c. 100d. 1490arrow_forwardC. With a 12-year design life, a flexible pavement was developed for the following daily traffic: 1300 single axles weighing 8,000 pounds each, 900 tandem axles weighing 15,000 pounds each, 20 single axles weighing 40,000 pounds each, and 200 tandem axles weighing 40,000 pounds each. 4 inches of hot-mix asphalt (HMA) wearing surface, 4 inches of hot-mix asphaltic base, and 8 inches of crushed stone subbase were used to construct the roadway. All drainage coefficients were 1.0, the total standard deviation was 0.5, the APSI was 2.0 (with a TSI of 2.5), and the reliability was 70%. What was the subgrade's soil resilient modulus when it was designed?arrow_forwardQ:Discuss various tests used for the quality of bitumen used in flexible pavements.arrow_forward
- answer with complete solution. Asap 1. determine the safe thickness of rigid pavement if the wheel load is 85 kN and f'c = 32 MPaarrow_forwardPavement Design and Analysis - Design a HMA pavement structure for a 6-lane divided urban highway using the AASHTO method to accommodate the traffic loads and conditions as follows. Give two alternative layer thickness combinations.arrow_forwardA six-lane divided highway is to be designed to replace an existing highway. The present AADT (both directions) of 6000 vehicles is expected to grow at 5% per annum. Assume SN = 4 and pt = 2.5. The percent of traffic on the design lane is 45%. The design life is 20 years and the vehicle mix is: Passenger cars (1000 lb/axle) = 60% 2-axle single-unit trucks (5000 lb/axle) = 30% 3-axle single-unit trucks (7000 lb/axle) = 10% Design a suitable pavement consisting of an asphalt mixture surface with an elastic modulus of 250,000 lb/in2, a granular base layer with a structural coefficient of 0.14 on a subgrade having a CBR of 10. Assume all mi values = 1. Use a reliability level of 85%, a standard deviation of 0.45, and a design serviceability loss of 2.0.arrow_forward
- highway engineering laboratory test CBR (California Bearing Ratio) 1. Importance of the test.2. Which of the basic properties of soil is represented by CBR test?3. How could the CBR value be used in pavement design?arrow_forwardA dual wheel having a load per tire of 5000 Ib, 70 psi pressure and μ = 0.5. Calculate thetotal pavement deflections due to the dual wheel by one-layer theory at the followingradial distances from the centerline of one tire: r=0, 3.5,10.5. (Use Pavement Thickness= 8in).arrow_forwardAssume that the overall pavement evaluation of Interstate highways in a district consists of four categories: Surface distress index = 75, drainage index = 80, roughness index = 85, and structural index = 90. For all indices, 100 represents the best condition. Calculate the overall pavement index (OPI) of the interstate highways in this district, if the relative weights of different indices are 0.20, 0.25, 0.28, and 0.27, respectively.arrow_forward
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