Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 19, Problem 14P
To determine
The design of a flexible pavement using the 1993 AASHTO procedure.
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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 1000, pi=4.2 and pt=2.5.
Growth rate= 4%
Design life= 20 years
Reliabilitylevel= 90%
Standard deviation= 0.45
The pavement will be exposed to moisture levels approaching saturation 20% of the time, and
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, 450kips/in2.
The traffic on the design lane of a proposed four-lane rural interstate highway consists of 25% 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
1885, pi = 4.2.
Growth rate = 6.5%
%3D
SN,
Design life = 20 yrs
Reliability level = 95%
Standard deviation = 0.45
Surface course
DI
%3D
SN2
%3D
D2
%3D
SN3
Base course
Subbase course
D3
Roadbed course
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 courses are 70 and 22, respectively, and Mr for the asphalt mixture, 3102 MPa
(450,000 lb/in?).
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).
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Similar questions
- 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.arrow_forwardA flexible pavement is designed to last 10 years to withstand truck traffic that consists only of trucks with two 18-kip single axles. The pavement is designed for a soil CBR of 10, an initial PSI of 5.0, a TSI of 2.5, an overall standard deviation of 0.40 and a reliability of 90%, and the structural number was determined to be 6. Determine the number of daily trucks traveling in the peak direction.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_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_forward2. You are asked to design a new flexible pavement structure for an existing road that will be totally replaced. You are provided with the following borehole results: a) Existing (Old) HMA - 135 mm b) Existing (Old) Granular A Base - 170 mm c) Existing (Old) Granular B Subbase - 340 mm d) Gravelly Silty Sand (Till) Subgrade (25 % 5-75 um) What is the current GBE for the existing pavement structure? What is the GBE for the same pavement structure when it was newly constructed?arrow_forwardQ1) If the traffic using the pavement grows at an annual rate of 4 present ,determine the design ESAL for 20 years, if ESAL for one year =78900?arrow_forward
- A flexible pavement has the following class loads during a particular hour of the day. i. ii. 80 buses with 2-axles (each axle load of 40 kN) ; ii. 160 trucks with 2-axles (from and rear axle loads of 40 kN and 80 kN, respectively) Find the equivalent standard axle load repetitions for this vehicle combination as per IRC 37-2012.arrow_forwardA flexible pavement is to be designed to last 10 years. The initial PSI is 4.2 and the TSI (the final PSI) is determined to be 2.5. The subgrade has a soil resilient modulus of 15,000 lb/in². Reliability is 95% with an overall standard deviation of 0.35. For design, the daily car, pickup truck and light van traffic is 40,000 and the daily truck traffic consists of 1500 passes of single-unit trucks with two single axles and 325 passes of tractor semi-trailer trucks with single, tandem, and triple axles. The axle weights are: Cars, pickups, light vans = two 2 kip single axles Single-unit truck = 8 kip single axle and 24 kip single axle Tractor semi-trailer truck = 10 kip single axle, 18 kip tandem axle, and 42 kip triple axle. ● ● M₂ and M3 are equal to 1 for the materials in the pavement structure. Four inches of hot- mix asphalt (HMA) is to be used as the wearing surface and 10 inches of crushed stone as the subbase. Determine the thickness required for the base if soil cement is the…arrow_forwardA flexible pavement is designed to last 10 years to withstand truck traffic that consists only of trucks with two 18-kip single axles. The pavement is designed for a soil CBR of 10, an initial PSI of 5.0, a TSI of 2.5, an overall standard deviation of 0.40 and a reliability of 90%, and the structural number was determined to be 6. On one section of this roadway, beneath an underpass, an engineer uses an 8-inch rigid pavement in an attempt to have it last longer before resurfacing. How many years will this rigid-pavement section last? (Given the same traffic conditions, modulus of rupture = 800 lb/in2, modulus of elasticity = 5,000,000 lb/in2, load transfer coefficient of 3.0 and drainage coefficient of 1.0.).arrow_forward
- 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).arrow_forwardExample: Design a new flexible pavement for a major interstate highway using the following conditions: Pavement location : Rural Number of lanes :2 lanes in each direction Total traffic during peak hour : 267 ESAL Design period : 16 years Growth factor : 12% Traffic distribution design of lane factor Lf: 65% Sub-grade CBR : 8% Standard deviation : 40% Overall serviceability loss: Po - Pt 4.2 -2 = 2.2 Solution: Step 1: Reliability (R) = 90% , Rural (Table 8.5) Step 2: Standard deviation (So) = 40% (Given) Step 3: Cumulative expected ESAL during design life in the design lane (W18) W18 = ADT x 365 x G x Df x Lf ADT = (Total traffic during peak hour) x 24 = 267 x 24 = 6408 EASL (1+i)"f-1 (1+0.12)16-1 G = = 45.613 i 0.12 22 Df = 0.93 2 lanes each direction (Table 8.6) W18 = 6408 x 365 x 45.613 x 0.93 x 0.65 = 64491246 x 64 x 106 ESAL D1 = ? D2 = ? D3 = ?arrow_forwardA flexible pavement is designed to last 10 years to withstand truck traffic that consists only of trucks with two 18-kip single axles. The pavement is designed for a soil CBR of 10, an initial PSI of 5.0, a TSI of 2.5, an overall standard deviation of 0.40 and a reliability of 90%, and the structural number was determined to be 6. Determine the number of daily trucks traveling in the peak direction. 150,814 B 75,407 C) 37,704 18,852arrow_forward
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