8 rational design criteria for rural roa

8/6/2019 8 Rational Design Criteria for Rural Roa

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RATIONAL DESIGN CRITERIA FOR LOWRATIONAL DESIGN CRITERIA FOR LOW

VOLUME ROADSVOLUME ROADS

Dr. U. C.Dr. U. C. SahooSahoo, BIT, BIT MesraMesraDr. M.Dr. M. AmaranathaAmaranatha ReddyReddy

Prof. K.Prof. K. SudhakarSudhakar ReddyReddy

IITIIT KharagpurKharagpur, India, India

BY

PIARC Int ernat ional seminar- SUSTAINABLE MAINTENANCE OF RURAL ROADS Rural Road System and

Accessibi l i t y t o Rural Areas21-23 January 2010


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IntroductionIntroduction Other district roads (ODR) and village roads (VR)Other district roads (ODR) and village roads (VR) -- ruralrural

roads in India covering aboutroads in India covering about 80% of the total road80% of the total roadlengthlength of the countryof the country

Rural transport sector is generally deprived of fundsRural transport sector is generally deprived of funds

In the absence of rational and practical guidelines andIn the absence of rational and practical guidelines and

specifications for the design, construction andspecifications for the design, construction andmaintenance, rural roads have generally not been ablemaintenance, rural roads have generally not been able

to provide satisfactory serviceto provide satisfactory service

Rational Design Criteria for Low Volume RoadsRational Design Criteria for Low Volume Roads


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IntroductionIntroduction A large number of roads are being constructed underA large number of roads are being constructed under

the Prime Ministerthe Prime Ministers rural connectivitys rural connectivity programmeprogramme

((PMGSYPMGSY))

RoadsRoads -- designed as per the guidelines given indesigned as per the guidelines given in

IRC:SP:20 (2002) and IRC:SP:72 (2007)IRC:SP:20 (2002) and IRC:SP:72 (2007)

Do not refer to any mechanistic principlesDo not refer to any mechanistic principles and there isand there is

also no reference to any documented performance dataalso no reference to any documented performance data

that formed the basis for these documentsthat formed the basis for these documents



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Failed Road



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Failed Road



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PerformancePerformance CriteriaCriteria

Most of the mechanisticMost of the mechanistic--empirical flexible pavementempirical flexible pavement

design methods consider the cracking of bound layersdesign methods consider the cracking of bound layersand rutting along the wheel paths as main distresses toand rutting along the wheel paths as main distresses to

be addressedbe addressed

In the case of low volume roads, the bituminousIn the case of low volume roads, the bituminous

surfacing is usually thin (less than 40 mm) and is notsurfacing is usually thin (less than 40 mm) and is not

expected to contribute significantly to the structuralexpected to contribute significantly to the structural

capacitycapacity



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Performance CriteriaPerformance Criteria

Another simple parameter used to evaluateAnother simple parameter used to evaluate

pavement performance is roughness, whichpavement performance is roughness, which

reflects the user perspectivereflects the user perspective

Rutting and roughnessRutting and roughness have been identified ashave been identified as

two major distresses in case of thin surfacedtwo major distresses in case of thin surfaced

granular pavementsgranular pavements



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SubgradeSubgrade Strain CriterionStrain Criterion

Granular Layer

Subgrade

E1, 1

E2, 2

z , zh

b

zaN=



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Performance EvaluationPerformance Evaluation

Site SelectionSite Selection

PMGSY roads inPMGSY roads in PashimPashim MedinipurMedinipur, West Bengal, West Bengal

200m length200m length

19 test sections19 test sections



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Field InvestigationsField InvestigationsField Performance Evaluation

Structural Evaluation Functional Evaluation

SurfaceManifestation

In-Situ Strength Visual Assessment Roughness

Deflection Penetration

Cracking

RavellingPotholesPatching

Using

MERLIN

Falling WeightDeflectometer

Dynamic ConePenetrometer

Rutting

LongitudinalDepression



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Evaluation of Pavements using FWDEvaluation of Pavements using FWD

Evaluation of pavement condition under dynamicEvaluation of pavement condition under dynamic

loading is considered to be more rationalloading is considered to be more rational

FWDFWD developed at Indian Institute of Technologydeveloped at Indian Institute of Technology

KharagpurKharagpur (Reddy 2003) was used for the(Reddy 2003) was used for the

deflection studiesdeflection studies



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Evaluation using IITFWDEvaluation using IITFWD



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Evaluation ofEvaluation ofPavements using DCPPavements using DCP



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Laboratory InvestigationsLaboratory Investigations

Liquid Limit and Plastic LimitLiquid Limit and Plastic Limit

Percentage Passing IS 75Percentage Passing IS 75 SieveSieve

Standard Proctor Compaction TestStandard Proctor Compaction Test

California Bearing Ratio TestCalifornia Bearing Ratio Test

UnconsolidatedUnconsolidated UndrainedUndrained TriaxialTriaxial CompressionCompression

TestTest

Resilient Modulus TestResilient Modulus Test




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MECHANISTIC EVALUATION OF PAVEMENT SECTIONSMECHANISTIC EVALUATION OF PAVEMENT SECTIONS

Test sections wereTest sections were

analysedanalysed

as two layeras two layer

systems usingsystems using 3D finite element3D finite element modelmodel

KK-- model developed bymodel developed by PandeyPandey and Naiduand Naidu(1994)(1994) for granular materials has beenfor granular materials has been

adopted in the present studyadopted in the present study

( )0.7375

3.47R

M =


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TRAFFIC

Traffic Volume CountTraffic Volume Count

Axle Load dataAxle Load data

Load Equivalency FactorLoad Equivalency Factor

Vehicle Damage Factor (VDF)Vehicle Damage Factor (VDF) Traffic Growth Rate (6 %)Traffic Growth Rate (6 %)


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R ti l D i C it i f L V l R dR ti l D i C it i f L V l R d


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AvgAvg ESALsESALs for Different Commercial Vehiclesfor Different Commercial Vehicles

VehicleVehicle Type of GoodsType of Goods AverageAverageESALESAL

LCVLCV LadenLaden 0.30.3

TruckTruck EmptyEmpty 0.20.2TruckTruck MoorumMoorum, Boulder, Stones, Boulder, Stones 16.316.3

TruckTruck BricksBricks 11.211.2

TruckTruck CementCement 5.85.8TruckTruck SandSand 8.88.8

TruckTruck Wood logsWood logs 6.66.6

TruckTruck Paddy/ RicePaddy/ Rice 11.511.5TruckTruck Vegetables/ FruitsVegetables/ Fruits 5.05.0

TruckTruck Fish/ Food ItemsFish/ Food Items 1.51.5

TruckTruck Goods/ Miscellaneous ItemsGoods/ Miscellaneous Items 7.97.9BusBus PassengersPassengers 1.61.6




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Vehicle Damage FactorVehicle Damage Factor

The VDF values for individual test sections varyThe VDF values for individual test sections vary

betweenbetween 1.70 and 3.39.1.70 and 3.39.

IRC: 37 (2001) recommends a value of 1.5 for roadsIRC: 37 (2001) recommends a value of 1.5 for roads

carrying traffic less than 150 commercial vehicles percarrying traffic less than 150 commercial vehicles per

dayday




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Terminal ConditionTerminal Condition

Riding Quality SurveyRiding Quality Survey

AA panel of experts travelled over some selected lowpanel of experts travelled over some selected low

volume road sections at a speed of 50 km/hvolume road sections at a speed of 50 km/h

Rated the pavements on a scale ofRated the pavements on a scale of 0 to 50 to 5 (0 for very(0 for very

poor to 5 for very good)poor to 5 for very good)




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Threshold limitsThreshold limits

Riding QualityRoughness

IRI (m/km)

Average Rut

Depth (mm)

Average

Longitudinal

Depression(mm)

Very Good < 4.5 < 2 8.5 >25 >7.3




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Pavement LifePavement Life

Pavement life was computed in terms of cumulativePavement life was computed in terms of cumulative

standard axle load repetitions using a traffic growthstandard axle load repetitions using a traffic growth

rate of 6%.rate of 6%.

TheThe rutting and roughness trends were extrapolatedrutting and roughness trends were extrapolated

to estimate the life of pavement for reaching theto estimate the life of pavement for reaching the

terminal conditions of 25 mm rut depth and 8.5 IRIterminal conditions of 25 mm rut depth and 8.5 IRI

(m/km) respectively(m/km) respectively




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SubgradeSubgrade Strain Criterion DevelopedStrain Criterion Developed

SubgradeSubgrade Strain criterion consideringStrain criterion considering

nonlinearity of granular layernonlinearity of granular layer

0.2720.029z N

=




28/31

100

1000

10000

1.0E+02 1.0E+03 1.0E+04 1.0E+05 1.0E+06 1.0E+07 1.0E+08

Standard Axle Load Repetitions

VerticalSubgradeStrain(

South Africa (Theyse et al., 1996)

Shell (1978)

Austroads (2004)

Author




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ConclusionsConclusions

To make the roads sustainable, design should beTo make the roads sustainable, design should be

accurate and economicalaccurate and economical

Nonlinear material property of the granular layerNonlinear material property of the granular layer

should be taken into account in mechanistic analysisshould be taken into account in mechanistic analysis

Terminal conditionTerminal condition

Roughness of 8.5 IRIRoughness of 8.5 IRI

Rutting of 25 mmRutting of 25 mm

Mechanistic Empirical Performance CriterionMechanistic Empirical Performance Criterion



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Acknowledgement

National Rural Roads Development Agency,

New Delhi


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8 rational design criteria for rural roa

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