DESIGN, CONSTRUCTION AND MAINTENANCE OF FLEXIBLE PAVEMENTS

DESIGN, CONSTRUCTION AND MAINTENANCE OF FLEXIBLE PAVEMENTSB.L.RAWATB.E.(HONS.), M.E.(HONS.),MBAEXECUTIVE ENGINEER (BUILDING CELL)PWD, CE OFFICE, JAIPUR

SECTION 1: DESIGNIRC GUIDELINESIRC: 37-2001GUIDELINES FOR THE DESIGN OF FLEXIBLE PAVEMENTS

IRC: 81-1997GUIDELINES FOR STRENGTHENING OF FLEXIBLE ROAD PAVEMENTS USING BENKELMAN BEAM DEFLECTION TECHNIQUE

IRC: 37-2001GUIDELINES FOR THE DESIGN OF FLEXIBLE PAVEMENTS

ScopeIt apply to design flexible pavement for Expressways, NH, SH, MDR and ODRs.Flexible Pavements includes bituminous surfacing, granular base and sub-base course conforming to IRC standards (section 400 and 500).These guidelines apply to new pavements.

Recommended Method of DesignIRC:37-1984 were applicable to design traffic upto 30 million standard axles (msa). Empirical methods have limitations regarding their applicability and extrapolation.IRC:37-2001 analytical method of design has been used to reanalyze the existing designs and develop a new set of designs for design traffic upto 150 msa.Design Approach and CriteriaThe flexible pavement has been modelled as a three layer structure and stresses and strains at critical locations have been computed using the linear elastic model FPAVE developed under the MORT&H Research Scheme R-56 Analytical Design of Flexible Pavements.3 types of pavement distressVertical Compressive Strain at the top of the subgrade (Permanent Deformation).Horizontal Tensile Strain at the bottom of the bituminous layer (Fracture in bituminous layer).Pavement Deformation within the bituminous layer.Based on the performance of existing designs and using analytical approach, simple design charts (Figs. 1 and 2) and a catalogue of pavement designs (Plates 1 and 2) have been added for use of field engineers.Plate 1: Subgrade CBR value 2% to 10% and design traffic range from 1 msa to 10 msa for an average annual pavement temperature of 35 degree Celsius.Plate 2: Subgrade CBR value 2% to 10% and design traffic range from 10 msa to 150 msa for an average annual pavement temperature of 35 degree Celsius.TrafficStandard Axle Load: 8160 kgs.Initial traffic after construction CVPD (gross weight: 3 ton or more).Traffic growth rate during the design life in percentage by traffic survey or as per IRC:108 (if adequate data not available, take 7.5%).Design life in number of years (NH and SH: 15 yrs, Expressway: 20 yrs, other roads: 10-15 yrs).Vehicle damage factor VDF (for new roads: by axle load survey).Distribution of commercial traffic over the carriageway.Indicative VDF valuesInitial Traffic Volume CVPDRolling/ Plain TerrainHilly Terrain0-1501.50.5150-15003.51.5More than 15004.52.5Distribution FactorCarriageway WidthDistribution FactorSingle-lane roadsTotal number of commercial vehicles in both directionsTwo-lane single carriageway roads75% of total number of commercial vehicles in both directionsFour-lane single carriageway roads40% of total number of commercial vehicles in both directionsDual two-lane carriageway roads75% of the number of commercial vehicles in each directionDual three-lane carriageway roads60% of the number of commercial vehicles in each directionDual four-lane carriageway roads45% of the number of commercial vehicles in each directionComputation of Design Traffic nN = 365X[(1+r) - 1] X (A X D X F) /rwhere,N= Cumulative number of standard axles in msaA= Initial traffic (CVPD) in the yr of completion of constructionD= Lane distribution factorF= Vehicle damage factorn= Design life in yearsr= Annual growth rate of commercial vehicle in %age xA= P(1+r)P= Number of commercial vehicles as per last countx= Number of yrs between the last count and yr of completion of constructionSubgradeAs per MORT&H Specifications for Expressway, NH, SH and MDR: 97% compaction (modified proctor density as per IS:2720 Part 8).As per MORT&H Specifications for ODR and VR: 97% compaction(standard proctor density as per IS:2720Part 7).IRC:36 Recommended Practice for the Construction of Earth Embankments for Road Works should be followed.For Expressway, NH and SH, the material used for subgrade should have the dry density of not less than 1.75 gm/cc.Four day soaked CBR value should be determined as per IS:2720 Part 16 Methods of Test for Soils.Design should be based on the CBR value of the weakest soil type proposed to be used for subgrade.

CBR (percent)Maximum variation in CBR values (for 3 specimen)515-10211-30331 and above5

Permissible Variation in CBR value

Atleast 3 samples should be tested on each type of soil at the same density and moisture content. Where variation is more than the above, the design CBR value should be average of test results from atleast 6 samples and not 3.

Pavement CompositionSub-base CourseBase CourseBituminous SurfacingSub-base CoursePlate 1: 1 to 10 msa and 2-10 CBRPlate 2: 10-150 msa and 2-10 CBRSub-base course: natural sand, moorum, gravel, laterite, kankar, brick, metal, crushed stone, crushed slag, crushed concrete or combination of materials.Granular sub-base course as per MORT&H Specifications Clause 401: 3 grading, passing 425 micron sieve, should have liquid limit and plasticity index not more than 25 and 6 respectively.The sub-base material should have minimum CBR of 20% upto 2 msa and 30% exceeding 2 msa.The thickness of sub-base should not be less than 150 mm for design traffic less than 10 msa and 200 mm for design traffic of 10 msa and above.The subgrade soil should have a minimum CBR of 2%. Where the CBR value is less than 2%, the design should be based on CBR value of 2% and a capping layer of 150 mm thickness of material with a minimum CBR of 10% should be provided in addition to sub-base.For stage construction, sub-base should be provided for ultimate pavement section for the full design life.Base CourseConventional Water Bound Macadam (WBM)Wet Mix Macadam (WMM)Other equivalent granular constructionMinimum thickness: 225 mm for traffic upto 2 msa and 250 mm for traffic exceeding 2 msa.Where WBM construction is adopted, for traffic more than 10 msa, the thickness of WBM base should be increased from 250 to 300 mm (i.e. 4 layers of WBM grades II and III each of 75 mm).

Bituminous SurfacingWearing Courses: surface dressing, open-graded premix carpet(PMC), mix seal surfacing(MSS), semi-dense bituminous concrete(SDBC) and bituminous concrete(BC).Binder Courses: Bituminous Macadam(BM)-recommended upto 5 msa and Dense Bituminous Macadam(DBM)-recommended for more than 5 msa.For practical purposes 10 mm BM can be taken as equivalent to 7 mm DBM for modifying the thickness of DBM layer.

Mastic Asphalt may be used at locations like bus-stop, roundabouts, intersections and bridges.Where the wearing surface adopted is open graded PMC of thickness upto 25 mm, the thickness of surfacing should not be counted towards the total thickness of the pavement as such surfacing will be purely for wearing and will not add to the structural capacity of the pavement.For traffic exceeding 150 msa, the pavement design appropriate to 150 msa may be chosen and further strengthening carried out to extend the life at the appropriate time based on pavement deflection measurements as per IRC:81.Substitution of DBM180 mm DBM = 125 mm DBM + 75 mm BM240 mm DBM = 185 mm DBM + 75 mm BM75 mm of BM = 55.85 mm of DBMDesign of Pavements of Expansive SoilsPotentially expansive soils, such as, black cotton soils are montmorillonite clays and are characterized by their extreme hardness and deep cracks when dry and with tendency for heaving during the process of wetting.Amount of volume change depends on:The dry density of the compacted soilThe moisture contentStructure of soil and method of compositionExpansive soils swell very little when compacted at low densities and high moisture content but swell gently when compacted at high densities and low moisture.A minimum density of 95% (standard proctor density) and 1-2% wet of OMC should be achieved in the field.Design CBR4-day soaked CBRBuffer LayerNon-expansive cohesive soil cushion of 0.6-1.0 m thicknessBlanket CourseWhere buffer layer is not economically feasible, atleast blanket course of 225 mm thickness and composed of coarse/medium sand or NP moorum having PI less then 5, should be provided on the expansive soil subgrade as sub-base over the entire formation width.Alternatively, lime-stabilised black cotton sub-base.DrainageNormal camber 1:40 for the black top surface.Cross slope of 1:20 for the berms.No standing water on either side.Minimum height of 1 m between subgrade level and highest water level.Bituminous SurfacingDesirably, 40 mm thick bituminous surfacing.ShouldersImpervious material.Lime stabilised black cotton soil shoulder of 150-200 mm thickness.SECTION 2: CONSTRUCTION??????SECTION 3: MAINTENANCEPart IHeadline Jaipur Newspaper (Monsoon 2010)The Government has ordered that all potholes in Rajasthan will be filled within next 48 hoursKANDHAL

B. L. RAWAT

B. L. RAWAT

B.L. RAWAT

KANDHAL

KANDHAL

KANDHAL

What should have been done!KANDHAL

KANDHAL

KANDHAL

IRC: 81-1997GUIDELINES FOR STRENGTHENING OF FLEXIBLE ROAD PAVEMENTS USING BENKELMAN BEAM DEFLECTION TECHNIQUE

ScopeTo evaluate strengthening requirement of existing flexible road pavements using the Benkelman Beam Deflection Technique.The recommendations based on the finding of MOST Research study (R-6).

Basic Principles of Deflection MethodThe deformation or elastic deflection under a given load depends on:Subgrade soil typeMoisture content and compactionThickness and quality of the pavement coursesDrainage conditionsPavement surface temperatureThe deflection is measured by Benkelman Beam which consists of a slender beam 3.66 m long pivoted at a distance of 2.44 m from the tip.Deflection may be rebound or residual.Rebound deflection is related to pavement performance.Residual deflection is due to non-recoverable deflection.

ProcedurePavement Condition Survey

Criteria for Classification of Pavement Sections

Classification Pavement ConditionGoodNo cracking, rutting less than 10 mmFairNo cracking or cracking confined to single crack in the wheel track with rutting between 10 mm and 20 mmPoorExtensive cracking and/or rutting greater than 20 mm. Sections with cracking exceeding 20% shall be treated as failed.Actual Deflection MeasurementsIn each road section of uniform performance, minimum of 10 points should be marked at equal distance in each lane of traffic for making the deflection observation in the outer wheel path.The interval between the points should not be more than 50 m.For roads having more than 1 lane, the points marked on adjacent lanes should be staggered.For lane width less than 3.5 m, measurement points should be 60 cm from pavement edge.When lane width is more than 3.5 m, 90 cm from edge.For divided 4 lane highway, it should be 1.5 m from edge.

Correction for Temperature VariationThe standard temperature is recommended to be 35C.Correction = 0.01 mm per C change from standard temp.The correction will be positive for temperature lower than 35C and negative for temperature higher than 35C.The measurement should be made at a depth of 40 mm in a hole of about 45 mm deep and about 10 mm diameter, drilled in the pavement and filled with glycerol.

Correction for Seasonal VariationThe measurement should be taken during the season when the pavement is in its weakest condition, i.e. soon after the monsoon.When deflections are measured during the dry months, they will require a correction factor which is defined as the ratio of the maximum deflection immediately after monsoon to that of the minimum deflection in the dry months.The correction factor depends on:Type of subgrade soilMoisture contentAverage annual rainfallFor this purpose, subgrade soil is divided into 3 categories:Sandy and gravelClay with low plasticity (PI 15)Clay with high plasticity (PI > 15)

Rainfall has been divided into 2 categories:Low rainfall (Annual rainfall 1300 mm)High rainfall (Annual rainfall > 1300 mm)Moisture content factors shall be obtained from charts for given field moisture content, type of subgrade soil and annual rainfall.For field moisture content, sample should be taken from 15 cm below subgrade level and 0.6 to 0.9 m from the edge, in each km.

Analysis of data for Overlay DesignCharacteristic DeflectionFor NH and SH: Dc = X + 2For other roads: Dc = X + Dc = Characteristic deflection, mm X = Individual Deflection, mm = Standard Deviation, mm

Design of OverlayThe overlay thickness design from Overlay Thickness Design Curves.It depends on:Characteristic deflectionMillion Standard Axle (msa)It gives the thickness in terms of Bituminous Macadam (BM) Overlay in mm.Equivalency factor1 cm BM = 1.5 cm WBM/ WMM/ BUSG1 cm BM = 0.7 cm DBM/ AC/ SDCFrom structural considerations, the recommended minimum bituminous overlay thickness is 50 mm BM with an additional surfacing course of 50 mm DBM or 40 mm BC.Before implementing the overlay, the existing surface should be corrected and brought to proper profile by filling the cracks, pot holes, ruts and undulations. No part of the overlay design thickness should be used for correcting the surface irregularities.SECTION 3: MAINTENANCEPart 2Causes of Failure of Flexible Pavement High traffic/axle loads Inadequacies in initial design /specifications Inadequacies in construction standards Lack of support from underlying layers Environmental factors such as oxidation of binder, ingress of water etc.Overloaded Trucks

VEHICLE DAMAGE FACTORLiddles DefinitionThe equivalence factor of axle is defined as the No. of passes of an axle carrying a standard load of 8160 kg. Which would do the damage to the road as on passes of the axle in consideration

VDF = [x/s]p

X =Load on axlep=4S =6.00 tonne for single-wheel single axle=8.16 tonne for dual-wheel single axle=15.2 tonne for dual-wheel tandem axle

METHOD OF AXLE LOAD SURVEYStatic methodsTRRL Portable Weigh Bridge.Wheel Weighing Pad (IRD-WW-6100)Dynamic methodsWeighinMotion Technology (WIM)Strain Guage (German Design)Hydraulic Displacemetn (German Design)Piezometric Quartz Crystal (French Design)Co-axial Cable Pressure Sensitive Piezo-Electric Meter (French Design)

LEGAL PROVISIONSMotor vehicle Act: 1988Sec.113limits the driving of any vehicle which exceeds the prescribed loadSec. 114empowered the transport deptt. To get such vehicles weighted and requires the drivers to off-load the excess weight at his own riskSec. 194punishment to violate of sec. 114Sec. 200compounding the fee

Inadequate drainage system

Inadequate design/drainage system

Types of Failure in Flexible PavementsCrackingDisintegrationDistortionCracking Alligator crackingBlock cracking Longitudinal CrackingTransverse cracking Slippage crackingReflective crackingEdge cracking

CrackingAlligator crackingClosely spaced crack pattern similar to that pattern on an alligators back.

Alligator cracking is well recognized as fatigue cracking.

Alligator cracking

Pavement is stressed to the limit of fatigue life by repetitive axle load repetitions.

Loads which are too heavy for pavement structure or more number of repetitions of a given load than considered for the design

Inadequate pavement thickness, inadequate design and lack of quality control Causes of Alligator CrackingCauses of Alligator CrackingInadequate pavement drainage due to which the underlying layers becomes saturated and lose strength.

High strains experienced by the bituminous layers when the underlying layers are weakened by excess moisture and fail prematurely in fatigue Slippage CrackingSlippage is the relative movement between the surface layer and the layer beneath

They show up first in the areas where vehicles brake, turn and accelerate.

Slippage cracks form a U-shape with top of the U pointing in the direction in which force is applied.Slippage cracking

CausesPoor bonding between the surface bituminous layer and the next underlying layer in the pavement structure.Turning wheels can cause the pavement surface to slide and deform.High stress due to braking and acceleration movements.Edge cracking Cracking only located within 1 to 2 feet of the edge of the pavement.

Failure begins at the edge of the pavement and progresses toward the wheel path.

Pavement edge distress can worsen the wheel path condition as it allow moisture to enter into the sub grade soils and base materials.

Edge crackingCausesLack of lateral support from the shoulder.

Excessive traffic loading at the pavement edge.

Inadequate surface drainage, especially during flooding conditions.

Inadequate pavement width which forces traffic too close to the pavement edge.Pavement Crust Composition

Base courseSubbase Bituminous SurfacingSubgradeDisintegrationDisintegration is the break-up of the pavement structure.

It involves loss of individual pieces or the separation of the individual components of the bituminous from each other.

Disintegration typically takes the form of ravelling, stripping and pot holes. Ravelling Dislodgement of aggregate particles.

It begins with the blowing off of the fine aggregates leaving behind pock marks on the surface.

Failure of binder to hold the aggregate shown up by pock marks or eroded areas on the surface.

94Ravelling Ravelling

Causes of RavellingPoor adhesion of bitumen binder to aggregate particles due to wet aggregate and also dust coating on the aggregates.

Inadequate compaction during construction does not permit the development of sufficient cohesion in asphalt mixture.

Use of inferior quality aggregate resulting in fracture, crushing and opening of new faces.96StrippingStripping is the separation of asphalt films from aggregate surfaces primarily due to the action of water.

The loss of bond between aggregates and asphalt binder.

Stripping begins at the bottom of the bituminous layer and progresses upward.

When stripping starts at the surface and progresses downwards it results in ravelling.Stripping

Stripping of aggregate

Causes Stripping is a difficult distress to identify because the surface manifestations can take numerous forms: rutting shoving, corrugations, ravelling or cracking.

Inadequate Pavement DrainageInadequate CompactionExcessive dust coating or inadequate drying of aggregate Use of Hydrophilic aggregates without anti-stripping agentsDEFINITIONSTRIPPING THE DISPLACEMENT OF BINDER FROM THE SURFACE OF AGGREGATES USUALLY BY THE ACTION OF WATER OR THE COMBINED ACTION OF WATER AND TRAFFIC.

IS:6241-1971 (SUBJECTIVE / VISUAL OBSERVATIONS)

Example of Stripping

Example of Stripping failureTonk road, JaipurExample of Stripping

Stripping test, without anti-stripping compound and with compoundSTRIPPING TESTAs per IS : 6241-1971DIFFERENT ADHESION TESTSTest results of aggregate and stripping value with anti-stripping compoundsS. N.Name of Quarry/Location (Aggregate)Sp.gr. (gm/cc)Water absorption (%)Impact Value (%)Stripping valueWithoutanti-stripAnti-stripping agent 'C' (% by wt. of bitumen)0.250.50.7511.25(i) JAIPUR ZONE1Gunawata2.580.420.5880%550052Bagru, Chitroli2.540.7721.9798%201510503Chandwaji2.610.2418.2390%35205054Bassi (Hardi)2.640.0920.890%2555005Harmada2.650.1423.0295%1550226Bassi (Jhar)2.690.3221.7895%302510057Khertal, Alwar2.600.1714.5985%20105028Moda Pahad, Jhunjhunu2.650.5311.545%550029Ghad, Tonk2.640.2724.3795%2015500(ii) AJMER ZONE10Tolamal, KSG2.650.3420.4650%10500211Nareli, Ajmer2.650.1419.4885%15505512Palara, Ajmer2.620.4630.4590%251050013Makreda, Ajmer2.60.6024.9495%10500214Masuda, BSR2.690.1516.5670%2515105015Guhana, BWR2.780.2017.7280%10500016Kalinjar, BWR2.70.1016.6480%3520105017Jawaja, Ajmer2.730.2721.0990%1510500S. N.Name of Quarry/Location (Aggregate)Sp.gr. (gm/cc)Water absorption (%)Impact Value (%)Stripping valueWithoutanti-stripAnti-stripping agent 'C' (% by wt. of bitumen)0.250.50.7511.2518Nagaur, HMP2.700.6218.9970%656050302019Balaji, NGR2.710.6719.4170%605530252020Jahajpur, Bhil.2.790.2919.940%00000(iii) JODHPUR ZONE21Devari Mata2.610.0518.0450%10500522Bhinmal-Jalore2.590.3415.9445%55000(iv) BIKANER ZONE23Randhisar2.640.4013.1255%10500024Bhappi, BKR2.571.4519.8840%3030151010(v) UDAIPUR ZONE25Kanpura, UDR2.810.1622.3940%2515105526Rajnagar2.810.0524.7980%80807520527Manpur, CGH2.650.1918.4840%15101055(vi) KOTA ZONE28S. Madhopur2.650.6019.0060%201050029Basani, Bundi2.670.5016.9580%2515105030Satoor, Bundi2.60.6320.3715%0000231Nanta, Kota2.541.2018.3165%151050032Anantpura2.561.0021.7175%5500033Baran quarry2.560.7719.1570%5500034Baran (HMP)2.60.7522.2280%2015105035Jhalawar2.51.5619.9670%7550036Teen-Dhar Jhalawar2.511.214.7585%50022SI No.AggregateAntistripping Agent % (By wt. of Binder)0.0 %0.25 %0.50 %0.75 %1.0 %1.Basalt50 %15 %5 %0 %2 %2.Limestone25 %10 %2 %0 %5 %3.Sandstone35 %15 %3 %2 %2 %4.quartzite80 %45 %10 %5 %5 %Test result of stripping value according to type of stoneMoRTH Specifications for Anti-stripping CompoundS. No.TestMethodLimit1.AppearanceVisualLiquid/Solid2.OdourSmellingAgreeable3.Specific gravity 270 CIS: 1202-19780.860-1.034.Pour Point 0C Maximum IS :1448425.Flash point 0 (COC) minimum IS :14481506.Water content per cent Vol. MaximumIS :14481.07.Solubility in diesel oil (HDO or LDO) in the ratio of 2:98 at 500 CAs given at clause 6.2.1Complete8.Total base value mg KOH/g minimumASTM D 6642009.Nitrogen content per cent Wt. MinimumElemental Analyzer7.010.Stripping value with bitumen containing 1 per cent Wt. Anti-stripping compound at 400 C 24 hoursIS: 6241. As given at clause 6.2.2No stripping11.Under water coating test Clause 6.2.3Complete coating12.Thermal stability at 1630 C for 5 hoursClause 6.2.4Should not lose its efficacy13.Boiling water test per cent minimum coatingASTM D 362595%14.Retained Marshall stability per cent minimumAs given at clause 6.2.575%

TESTING OF ANTI- STRIPPING COMPOUNDSS. No.TestMethodLimit Anti stripping Compound Test resultsCompound "A"Compound "B"Compound "C"1.AppearanceVisualLiquid / SolidLiquidSemi-liquid pasteSemi -liquid paste2.OdourSmellingAgreeableAgreeableAgreeableAgreeable3.ColourVisual-BlackBrownDark Brown4.Pour point C MaximumIS:144842C16C33C36C5.Flash point C MinimumIS: 1448150C212 C142 C148C6.Solubility in diesel oil (HDD or LDO) in the ratio of 2:98 at 50C)MoRTH specificationComplete100%100%100%7. Stripping value with bitumen containing I% wt.IS:6241 MoRTH specificationNo strippingTable -5Table -5Table -58.Under water coating test MoRTH specificationComplete coating95%90%100%9.Thermal stability at 163C 5 hours MoRTH specificationShould not lose its efficiency98%90%100%10.Retained Marshall stability % Mini mumMoRTH specification75%80 .00%93.39%98 .57%MoRTH CIRCULARSD.O. No. RW/PL-30(95)/77Date- 15/4/85Use of Anti-stripping chemicals for bituminous Road works ANSTRIP, HINUAT TR 100RW/NH/VI/50(8)/84-NH StdDate- 19/8/87Use of anti-stripping compounds in bituminous mixer-Guidelines there inRW/NH/VI-50(8)/88/NH StdDate- 9/10/87Use of anti-stripping compounds in bituminous mixer-GuidelinesRW/NH-VI-50(8)/84-NH(Std.) DO-II Date- 15/4/88Use of anti-stripping compounds in bituminous mixers Guidelines regardingP.W.D. Rajasthan

F.11/meeting/OC/EE (D&T) D-483Date- 1/8/2001PotholesPotholes are relatively small hole that goes through the bituminous surface and down in the base course.Frequently on pavements having thin bituminous courses (25-50 mm) and rarely occurs on pavements with thickness more than 100 mm

PotholeCausesRavelling, stripping or cracking of the pavement surface. Improper drainage facilities both surface and subsurface.Freeze and thaw cycles.

Engagement of pavements without renovation, even after expiry of design period.115Distortion Distortion is characterized by a permanent change in the shape of the pavement or pavement layer. Different forms of distortion in flexible pavements are:

Rutting (rural highways)Corrugations (urban intersections)Shoving (urban sections)Rutting Ruts are depressions which occur in the wheel path

Rutting in bituminous layers is generally not significant.

Rutting is significant if the bituminous layers, underlying layers or subgrade soil is overstressed and significant densification or shear failure occurs.

RuttingCausesInadequate compaction of pavement layers. Improper Drainage

Most common causes of rutting in a bituminous layer are

High Asphalt ContentUse of too many rounded particles in both coarse and fine aggregate.Use of excessive fines.ConclusionsAdequate DesignAdequate SpecificationAdequate Construction StandardsProper DrainageQuality ControlProper Maintenance

THANKS!Open for DiscussionRecommended type and thickness of Bituminous wearing courses under different situationsSl. No.Type of Base/Binder courseType of Bituminous Wearing CourseAnnual RainfallL: 3000 mmDesign traffic (msa)1.WBM,WMM, Crushed Macadam, Built up Spray Grout20 mm PMC with sand seal coatL and M