Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 19, Problem 8P
To determine
A suitable depth of the asphalt pavement using the AASHTO method.
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section of a two-lane rural highway is to be realigned and replaced by a four-lane highway
with a full-depth asphalt pavement. 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. It is expected that construction will be completed five years from now, and
pi =4.5 and pt = 2.5. Growth rate = 4%. Design life = 20 years.
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 (Mr=30000 lb/in2
) and 22 (Mr=13500
lb/in2
), respectively, and Mr for the asphalt mixture, 400,000 lb/in2
.
A section of a two-lane rural highway is to be realigned and replaced by a four-lane highway with a full-depth asphalt pavement. The AADT (both ways) on the existing section can be represented by 500 ESAL. It
is expected that construction will be completed 5 years from now. If the traffic growth rate is 5 percent and the effective CBR the subgrade on the new alignment is 8.5, determine a suitable depth of the
asphalt pavement (in inches) using the AASHTO method. Take the design life of the pavement as 20 years. The resilient modulus of the asphalt (EAC) is 400,000 lb/in.². Assume m, for the subgrade is 1 and the
percent of traffic on the design lane is 45 percent. Use a reliability level of 90 percent, a standard deviation of 0.45, and a design serviceability loss of 2.0.
inches
A section of a two-lane rural highway is to be realigned and replaced by a four-lane highway with a full-depth asphalt pavement. The AADT (both ways) on the existing section can be represented by 750 ESAL. It is expected that construction will be completed 5 years from now. If the traffic growth rate is 2 percent and the effective CBR of the subgrade on the new alignment is 9.0, determine a suitable depth of the asphalt pavement (in inches) using the AASHTO method. Take the design life of the pavement as 20 years. The resilient modulus of the asphalt
(EAC)
is 450,000 lb/in.2. Assume
mi
for the subgrade is 1 and the percent of traffic on the design lane is 45 percent. Use a reliability level of 90 percent, a standard deviation of 0.45, and a design serviceability loss of 2.0.
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- A section of a two-lane rural highway is to be realigned and replaced by a four-lane highway with a full-depth asphalt pavement. The AADT (both ways) on the existing section can be represented by 750 ESAL. It is expected that construction will be completed 5 years from now. If the traffic growth rate is 2 percent and the effective CBR of the subgrade on the new alignment is 9.0, determine a suitable depth of the asphalt pavement (in inches) using the AASHTO method. Take the design life of the pavement as 20 years. The resilient modulus of the asphalt (EAC) is 450,000 lb/in. ². Assume m; for the subgrade is 1 and the percent of traffic on the design lane is 45 percent. Use a reliability level of 90 percent, a standard deviation of 0.45, and a design serviceability loss of 2.0. 8.25 inchesarrow_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_forwardQ2: 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).arrow_forward
- A 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_forwardDetermine the total thickness of flexible pavement (in mm) for a two Lane undivided carriageway using the following data:arrow_forwardNonearrow_forward
- Case Study 2: Determine the expected AADT over the 10 year design period in one direction if the initial traffic in 2020 data is 1970, the first 5 year has 5% growth rate and the remaining years is 4%. The total traffic distribution is car/jeep 44%, buses = 26% and truck = 30%. Design the thickness of the flexible %3D pavement using the Road Note Catalogue 31 and the CBR of the subgrade is 5%. What is 80 equivalent single application load of the significant damage to pavement of bus = 0.45 and truck = 1.0.arrow_forward12. 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_forwardA flexible pavement was designed for the following daily traffic with a 12-year design life: 1300 single axles at 8,000 lb each, 900 tandem axles at 15,000 lb each, 20 single axles at 40,000 lb each, and 200 tandem axles at 40,000 lb each. The highway was designed with 4 inches of hot-mix asphalt (HMA) wearing surface, 4 inches of hot-mix asphaltic base, and 8 inches of crushed stone subbase. The reliability was 70%, overall standard deviation was 0.5, ¨PSI was 2.0 (with a TSI of 2.5), and all drainage coefficients were 1.0. What was the soil resilient modulus of the subgrade used in design?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_forwardThe 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.arrow_forward▪ A roadway is determined to have 400 18-kip single axles, 200 24-kip single axles, and 100 40- kip tandem axles per day. The subgrade CBR is 10 and the roadway pavement is designed for an overall standard deviation of 0.45, a reliability 99.9% and the initial PSI is 4.5 and the TSI is 2.5. One newly constructed section of this roadway is a rigid pavement designed with a 10- inch slab with a modulus of rupture of 900lb/in², and a modulus of elasticity of 4.5x10 lb/ in², and a joint transfer coefficient of 3.2. Another newly constructed section of the same roadway is a flexible pavement with a 4-in sand-mix asphaltic concrete surface, 9-in dense- graded crushed stone base and a 9-in crushed-stone subbase. If the roadway has three lanes in each direction and is conservatively designed, which of the pavement sections will last longer and by how many years if all drainage coefficients are 1.0?arrow_forward
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