Explanation Given: Number of single axle traffic at 10 , 000 lb each are 300 . Number of single axle traffic at 18 , 000 lb each are 20 . Number of single axle traffic at 23 , 000 lb each are 100 Number of tandem axle traffic at 32 , 000 lb each are 100 Number of single axle traffic at 32 , 000 lb each are 90 . Number of triple axle traffic at 40 , 000 lb each are 100 . The overall standard deviation is 0.5 . The value of initial PSI is 4.5 The value of TSI is 2.5 The drainage coefficient is 1 The thickness of asphalt wearing surface is 4 inch . The thickness of hot mix asphalticbase is 4 inch . The thickness of crushed stone sub base is 10 inch . The design life of the pavement is 20 years . The CBR value is 8 . Formula Used: Write the expression for the structural number. SN = a 1 D 1 + a 2 D 2 M 2 + a 3 D 3 M 3 …… (I) Here, a 1 is the structural layer coefficient of the hot mix asphalt wearing surface layer, a 2 is the structural layer coefficient of soil-cement base layer, a 3 is the structural coefficient of crushed stone sub-base layer, D 1 is the thickness of the wearing surface layer, D 2 is the thickness of the base layer, D 3 is the thickness of the sub-base layer, M 2 is the drainage coefficient for base and M 3 is the drainage coefficient for sub-base. Write the expression for the 18 -kips equivalent single axle load. log 10 W 18 = [ Z R S 0 + 9.36 [ log 10 ( SN+1 ) ] − 0.20 + log 10 [ Δ PSI / 2.7 ] 0.40 + [ 1094 / ( SN + 1 ) 5.19 ] + 2.32 log 10 M R − 8.07 ] ……. (II) Here, Z R is the reliability, S 0 is the overall standard deviation, Δ PSI is the loss in serviceability from the time the pavement is new until it reaches its TSI, M R is the soil resilient modulus of the subgrade and W 18 is the 18 -kips equivalent axle load. Write the expression for the soil resilient modulus. M R = 1500 × C B R …… (III) Here, M R is the soil resilient modulus and C B R is the California Bearing Ratio. Write the expression for the total axle load factor. W n = A F n × Number of axles …… (IV) Here, W n is the total axle load factor for a particular load, A F n is the axle load factor . Write the expression for the loss in serviceability. ΔPSI = Initial PSI − TSI …… (V) Here, ΔPSI is the loss in serviceability. Write the expression for the total equivalent load. Total EL = W 10 s + W 18 S + W 23 S + W 32 S + W 32 Tandem + W 40 Triple …… (VI) Write the expression for the design lane 18-kip equivalent single axle load. Des W 18 = T L Equivalent × D L × 365 …… (VII) Here, Des W 18 is the design lane 18-kip equivalent single axle load and D L is the design life. Calculation: Refer Table 4.5 “Structural-layer coefficients” of the book “Principles of Highway Engineering and traffic, 6 th Edition” For the asphalt wearing surface . a 1 = 0.575 For the asphalt base. a 2 = 0.40 For the crushed stone sub base. a 3 = 0.11 Substitute 0

The reliability of the pavement to last 20 years .

Principles of Highway Engineering and Traffic Analysi (NEW!!)

6th Edition

ISBN: 9781119305026

Author: Fred L. Mannering, Scott S. Washburn

Publisher: WILEY

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Question

Chapter 4, Problem 25P

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