### Designing Flexible Pavement for a 10-Year Lifespan#### IntroductionThe project involves designing a flexible pavement to last 10 years. The initial Present Serviceability Index (PSI) is 4.2, and the Terminal Serviceability Index (TSI, or final PSI) is determined to be 2.5. #### Soil and Reliability Specifications- **Subgrade Soil Resilience Modulus**: 15,000 lb/in².- **Reliability**: 95% with an overall standard deviation of 0.35.#### Traffic Data- **Daily Traffic**: - **Cars, Pickup Trucks, Light Vans**: 40,000 passes. - **Single-Unit Trucks**: 1,500 passes. - **Tractor Semi-Trailer Trucks**: 325 passes.#### Axle WeightsThe axle weights for different vehicle categories are as follows:- **Cars, Pickups, Light Vans**: Two 2 kip single axles.- **Single-Unit Truck**: - 8 kip single axle. - 24 kip single axle.- **Tractor Semi-Trailer Truck**: - 10 kip single axle. - 18 kip tandem axle. - 42 kip triple axle.#### Material and Structural Layer Details- **Materials Multiplier**: Values \(M_2\) and \(M_3\) are both equal to 1.- **Layer Composition**: - 4 inches of Hot-Mix Asphalt (HMA) to be used as the wearing surface. - 10 inches of crushed stone as the subbase.#### ObjectiveDetermine the thickness required for the base layer if soil cement is to be used as the material for the base.### AnalysisThe following steps should be performed to determine the base thickness:1. **Traffic Analysis**: Calculate the Equivalent Single Axle Load (ESAL) for the 10-year period.2. **Structural Number (SN) Calculation**: Utilize the AASHTO pavement design formula to find the required Structural Number.3. **Layer Coefficients & Thicknesses**: - Derive coefficients for HMA, crushed stone, and soil cement. - Calculate respective layer thicknesses to meet the structural number requirement.### ConclusionThis detailed engineering analysis will ensure the designed pavement meets the specified durability and performance criteria

Design period = 10 yearsIntial PSI = 4.2Final PSI =2.5Soil resilient modulus, MR = 15,000 lb/in²For…

A 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 material to be used.

A 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 material to be used.

Structural Analysis

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ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Concept explainers

Drainage of Pavements

Pavement Drainage holds ample significance, as it prevents the accumulation of water or any liquid on the surface of pavements and ensures proper drainage system. With proper design and gradual slopes provided, the water gets easily removed from the surface into the drains, which are essential during heavy rains and unusual weather conditions keeping it less prone to accidents and increasing the durability of the pavement structure.

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### Designing Flexible Pavement for a 10-Year Lifespan

#### Introduction
The project involves designing a flexible pavement to last 10 years. The initial Present Serviceability Index (PSI) is 4.2, and the Terminal Serviceability Index (TSI, or final PSI) is determined to be 2.5.

#### Soil and Reliability Specifications
- **Subgrade Soil Resilience Modulus**: 15,000 lb/in².
- **Reliability**: 95% with an overall standard deviation of 0.35.

#### Traffic Data
- **Daily Traffic**:
- **Cars, Pickup Trucks, Light Vans**: 40,000 passes.
- **Single-Unit Trucks**: 1,500 passes.
- **Tractor Semi-Trailer Trucks**: 325 passes.

#### Axle Weights
The axle weights for different vehicle categories are as follows:
- **Cars, Pickups, Light Vans**: Two 2 kip single axles.
- **Single-Unit Truck**:
- 8 kip single axle.
- 24 kip single axle.
- **Tractor Semi-Trailer Truck**:
- 10 kip single axle.
- 18 kip tandem axle.
- 42 kip triple axle.

#### Material and Structural Layer Details
- **Materials Multiplier**: Values \(M_2\) and \(M_3\) are both equal to 1.
- **Layer Composition**:
- 4 inches of Hot-Mix Asphalt (HMA) to be used as the wearing surface.
- 10 inches of crushed stone as the subbase.

#### Objective
Determine the thickness required for the base layer if soil cement is to be used as the material for the base.

### Analysis
The following steps should be performed to determine the base thickness:
1. **Traffic Analysis**: Calculate the Equivalent Single Axle Load (ESAL) for the 10-year period.
2. **Structural Number (SN) Calculation**: Utilize the AASHTO pavement design formula to find the required Structural Number.
3. **Layer Coefficients & Thicknesses**:
- Derive coefficients for HMA, crushed stone, and soil cement.
- Calculate respective layer thicknesses to meet the structural number requirement.

### Conclusion
This detailed engineering analysis will ensure the designed pavement meets the specified durability and performance criteria

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2 a. The scales reading the weight of each truck were reading 10% low. Calculate the ESAL for the following truck, assuming flexible pavement for both the axle/axle group weight and the weight increased by 10% 12,000 lbs 40,000 lb shoporst 20,000 b. Calculate the ESAL for the above truck, assuming rigid pavement. 20,000
A rigid pavement is designed with an 11-inch slab thickness, 90% Rellability (ZR = -1.282), Es = 4 million psi, modulus of rupture of 600 psi, modulus of subgrade reaction of 150 lb/in?, a 2.8 load transfer coefficient, initial PSI = 4.8, final PSI of 2.5, overall standard deviation of 0.35, and a drainage coefficient of 0.80. The pavement has a 20-year design life. The pavement has three lanes in one direction (PDL = 0.80) and is conservatively designed for trucks that have one 20,000-lb single axle load (1.58), one 26,000-lb tandem axle (0.619), and one 34,000-b triple axle (0.593). What is the daily estimated truck traffic on the three lanes? logia (APSI) S,C¢(D@7% – 1.132) 3.0 [1.62410x10 |(D + 1)*46 | log10 (W) = Zg5, + 7.35 (log,0( D + 1)) – 0.06 +: +(4.22 - 0.327SI) log10 1+ 18.42 215.63/ De75 - 0.25
1. During the AASHO road test, ONLY flexible pavements were constructed and tested.a. Trueb. False2. The AASHO present serviceability rating (PSR) was considered an objective quantity used to establish the performance of highway pavement in terms of applied traffic.a. Trueb. False3. The AASHTO present serviceability index (PSI) correlates the PSR to actual pavement performance in terms of applied traffic, and select distresses.a. Trueb. False4. There is only one AASHTO PSI equation that applies to both flexible and rigid pavements.a. Trueb. False5. The AASHTO PSI scale ranges from:a. 0-5b. 0-10c. 0-100d. None of the above
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