Highway Construction

Table of Contents
1. Highway Construction
2. Earthwork
3. Embankments
4. Construction Of Earth Roads
5. Construction Of Gravel Roads
6. Construction Of Water Bound Macadam (Wbm) Roads
7. Construction Of Bituminous Pavements
8. Bituminous Construction Procedures
9. Construction Of Cement Concrete Pavements
10. Construction Of Joints In Cement Concrete Pavements
11. Construction Of Soil-stabilized Roads
12. Checks, Quality Control And Final Notes
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Highway Construction

Types of Highway Construction

• Earth roads and gravel roads
• Soil-stabilized roads
• Water Bound Macadam (WBM) roads
• Bituminous or black-top roads
• Cement concrete roads

Pavement Types - Selection Factors

The selection of base course and surface course depends on the following factors:

• Type and intensity of traffic
• Funds available for construction and for subsequent maintenance
• Subgrade soil and drainage conditions
• Availability of construction materials at site
• Climatic conditions
• Plant and equipment available
• Time available for completing the project
• Altitude at which construction must be carried out

Typical traffic capacity guidelines (general):

• Low-cost earth/gravel roads: about 30 to 200 tonnes per day
• WBM roads: may be suitable for traffic over 500 tonnes per day
• Bituminous and cement concrete pavements: suitable for heavier traffic densities

In highway construction a staged construction technique is often adopted to manage traffic and construction resources.

Earthwork

Earthmoving Equipment

• Bulldozer - used for clearing site, opening pilot roads, moving earth for short hauls (~100 m) and general grading tasks.
• Scraper - self-propelled machine that can cut, haul and discharge material in uniform layers; not suited to very stiff materials.
• Power shovel - excavates earth of most classes (except hard rock) and loads wagons; often mounted on crawler tracks for mobility at low speeds.
• Dragline - excavates soft earth and deposits near banks or loads wagons; can operate from the ground and need not enter the excavation pit.
• Clamshell - useful for excavation of soft to medium materials and loose materials at or below the natural ground surface.
• Hoe - excavates below the machine location with precise depth control; effective for stiff materials that draglines cannot handle.

Do you know? The power shovel is most effective when excavating from a lower level and when the excavation face is not too shallow.

Embankments

When the highway grade line must be raised above existing ground level, an embankment is constructed. Reasons for raising the grade include keeping the subgrade above high groundwater table, preventing damage from surface and capillary water, and maintaining vertical alignment standards.

Design Elements of Highway Embankments

• Height - depends on desired grade line, soil profile and topography; foundations of weak soils may govern allowable height.
• Fill material - granular soils are preferred; silts and clays are less desirable; organic soils (peat) are unsuitable; lightweight fills (e.g., cinder) may be used where foundation is weak.
• Settlement - consolidation of saturated foundation clays may be accelerated by vertical sand drains; typical drain diameters are 30 to 60 mm with spacings 2.5 to 6.0 m in a hexagonal pattern; a horizontal sand blanket 40-60 cm thick is often placed across the embankment bottom.
• Stability of foundation - assessment required when weak strata exist beneath the embankment; essential for high embankments.
• Stability of slopes - slopes must be designed to a minimum factor of safety of about 1.5 to prevent failure under adverse moisture and loading conditions.

Construction of Embankments

• The embankment is usually constructed by the rolled earth method, placing fill in relatively thin layers and compacting each layer. Hydraulic filling is an alternative for specific conditions.
• Compaction is carried out at or near the optimum moisture content (OMC) to achieve maximum dry density using suitable compaction equipment.
• Preparation of subgrade includes site clearance, grading to required embankment or cut section levels and compaction.

Compacting Equipment

Soil compaction in the field is achieved by rolling, ramming or vibration. Sands are compacted also by watering, ponding and jetting.

Rollers

• The principle of rolling is application of pressure, slowly increasing then decreasing to achieve density.
• Types of rollers:
• Smooth-wheeled rollers - suitable for a wide range of soils, particularly granular soils; crushing action helpful where required.
• Pneumatic-tyred rollers - suitable for non-plastic silts and fine sands; provide kneading action in addition to pressure.
• Sheepsfoot rollers - effective for clayey soils; efficiency depends on roller weight and number of feet in contact.

Rammers

• Used to compact relatively small areas or where rollers cannot operate (trenches, foundations, slopes).

Do you know? The output (productivity) of a rammer is much lower than that of a roller.

Vibrators

• Most suited for compacting dry cohesionless granular materials; vibrator-mounted rollers combine rolling and vibration effects.

Watering (Jetting/Ponding)

• Efficient for compacting cohesionless sands by reducing voids and increasing density.

Field Control for Compaction

• Two essential field control tests are measurement of moisture content and measurement of dry density.
• Moisture content may be measured by rapid site methods before compaction; if maintained near OMC, dry density is then controlled by adjusting number of passes and layer thickness.
• Dry density is commonly measured by the sand replacement method or other suitable field methods.

Construction Of Earth Roads

• Maximum cross slopes of 1 in 20 (5%) are usually recommended to avoid erosion and cross ruts.
• Steep cross slopes (1 in 20 to 1 in 33) help keep pavement free of standing water; otherwise pervious soils allow water to soften the subgrade.
• Construction steps for earth roads are given below.

1. Material

Soils suitable for earthen roads generally have the following properties:

The pavement section is generally constructed from soil available at site or nearby borrow pits to minimise haul.

2. Location

• Centre line and road edges are marked on ground using wooden pegs along the alignment.

3. Preparation of Subgrade

Operations include:

• Clearing the site
• Excavation and construction of fills to obtain desired grade
• Shaping and compaction of subgrade

4. Pavement Construction

• Soil is mixed, spread and rolled in layers with compacted thickness not exceeding 10 cm.
• A dry density of at least 95% of IS light compaction (or specified field requirement) is desirable.

5. Opening to Traffic

• Compacted earth roads are allowed to dry for a few days before opening to traffic.

Construction Of Gravel Roads

• Gravel roads can serve approximately 100 tonnes per day for pneumatic-tyred vehicles or about 60 tonnes per day for iron-tyred vehicles per lane.
• Two construction types: feather-edge and trench type. The trench type provides better confinement and is generally preferred.

Construction Steps

• Material - hard crushed stone or gravel of specified gradation; material is stacked near the road.
• Location - alignment and carriageway width determined; trenches (if used) are excavated to match carriageway width.
• Preparation of subgrade - trench width equals carriageway width where trench type is used.
• Pavement construction - layers are rolled using smooth-wheeled rollers, starting from edges and overlapping longitudinally by at least half the roller width.
• Opening to traffic - allowed after final rolling and drying.

Construction Of Water Bound Macadam (Wbm) Roads

• WBM can be used as sub-base, base course or surfacing course.
• Macadam refers to a base made of crushed or broken aggregate mechanically interlocked by rolling with voids filled by screenings and binding material aided by water.

Specifications of Materials for WBM

• Coarse aggregate - hard crushed aggregates or broken stones preferred; soft aggregates (overburnt bricks, kankar, laterite) may be used where suitable; blast furnace slag is also used in some regions.

Size and Grading Requirements

• Grading No. 1: aggregates 90-40 mm - suitable for sub-base; compacted thickness ~100 mm.
• Grading No. 2: aggregates 63-40 mm.
• Grading No. 3: aggregates 50-20 mm - compacted layer thickness normally 75 mm.

Screenings and Binding Material

• Screenings fill voids in compacted coarse aggregate layers. Non-plastic materials such as kankar nodules, morum or gravel may be used if liquid limit < 20%, plasticity index < 6% and fines < 10% passing 0.075 mm sieve.
• Binding material (fine-grained) prevents raveling; kankar nodules or limestone dust can be used. For WBM surface courses the IP range 4-9% is acceptable; for base/sub-base binding materials IP < 6% is preferred.

Do you know? If crushable screenings such as moorum or gravel are used, binding material is not required except for surface courses.

Construction Steps for WBM

• 1. Preparation of foundation - subgrade, subbase or base is prepared to required grade and camber; dust and loose materials are cleaned. On existing roads, depressions and potholes are filled and corrugations scarified and reshaped.
• 2. Lateral confinement - shoulders are constructed in advance to the thickness of the compacted WBM layer to provide lateral support.
• 3. Spreading of coarse aggregates - aggregates are spread in uniform layers.
• 4. Rolling - start from edges and progress towards centre; continue until interlocking achieved.
• 5. Application of screenings - dry screenings are applied in several applications to fill voids; dry rolling and brooming continue during spreading.
• 6. Sprinkling and grouting - surface sprayed with water; wet screenings swept into voids.
• 7. Application of binding material - binding material applied in thin layers and rolled; water is applied and slurry worked into voids by brooms.
• 8. Setting and drying - allow WBM course to set overnight; rectify any 'hungry' spots and do not allow traffic until the layer is set and dried.

Checking Surface Evenness and Rectification

• Check longitudinal surface evenness with a 3.0 m straight edge.
• Record undulations exceeding 12 mm for grading No. 1 and 10 mm for gradings 2 and 3 in each completed 300 m; the maximum number allowed is 30 per 300 m.
• Mark spots with 15 mm undulation for rectification.
• Check cross profile with camber template; maximum variation from design camber should not exceed 12 mm for grading No. 1 and 8 mm for gradings 2 and 3.

Construction Of Bituminous Pavements

Common construction techniques:

• Interface treatments: prime coat and tack coat
• Surface dressing and seal coat
• Grouted or penetration type constructions: penetration macadam and built-up spray grout (BSG)
• Premix methods: bituminous bound macadam, carpet, bituminous concrete, sheet/rolled asphalt, mastic asphalt

1. Interface Treatment

Before laying a new bituminous layer over an existing layer, clean the surface and apply a thin bituminous binder to ensure a good bond between old and new layers.

Prime Coat

• Prime coat is a first application of a low-viscosity bituminous liquid (e.g., MC or SC cutback) over porous or absorbent surfaces such as WBM.
• Its object is to plug capillary voids and bind loose mineral particles; the binder must penetrate the surface pores.
• The prime coat surface is normally allowed to cure for at least 24 hours with no traffic.

Do you know? Prime coat application rate is typically 7.3 to 14.6 kg per 10 m2 depending on surface porosity.

Tack Coat

• Tack coat is applied over relatively impervious surfaces such as existing bituminous or concrete pavements or over a primed WBM surface to ensure bond with the new bituminous layer.
• Higher viscosity materials (hot bitumen) or bituminous emulsions (in cold application) are used.

Do you know? Tack coat application rate is usually 4.9 to 9.8 kg per 10 m2 depending on the surface type.

2. Bituminous Surface Dressing (BSD)

• Surface dressing provides a thin wearing course over an existing pavement.
• Single coat surface dressing consists of a single binder application followed by spreading and rolling of aggregate cover.

Main functions of BSD:

• Provide a thin wearing course and protect the base course
• Waterproof the pavement surface to prevent ingress of surface water
• Provide dust-free surface in dry weather and reduce mud in wet weather

Seal Coat

• Seal coat is recommended over open-graded bituminous layers (premixed carpet, grouted macadam) or worn bituminous surfaces.
• Premixed sand-bitumen seal coats are commonly used over premixed carpets.

Main functions of seal coat:

• Seal surfacing against ingress of water
• Develop skid-resistant texture
• Rejuvenate weathered bituminous surfaces

3. Grouted or Penetration Type Constructions

(a) Penetration Macadam

• Used as base or binder course. Coarse aggregates are spread and compacted dry; hot bituminous binder of relatively high viscosity is sprayed so it penetrates voids and binds aggregates.
• Full grout is used in heavy rainfall regions; semi-grout for moderate rainfall and traffic.

(b) Built-up Spray Grout (BSG)

• BSG consists of two compacted crushed aggregate layers with bituminous binder applied after each layer and finished with key aggregates to form a total compacted thickness of 75 mm.
• Commonly used for strengthening existing bituminous pavements; a wearing course is provided before opening to traffic.

4. Premix Methods

Aggregates and bituminous binder are mixed thoroughly before spreading and compaction. Types include bituminous macadam, premixed carpet, bituminous concrete, sheet asphalt and mastic asphalt.

(a) Bituminous Macadam (BM)

• BM is a premix used as base or binder course and normally covered by a wearing course before exposure to traffic.
• BM has better load dispersion and durability compared to WBM base courses.

(b) Premixed Carpet (PC)

• PC uses coarse aggregates (12.5 and 10 mm), premixed with bitumen and compacted to ~20 mm thickness as a surface course.
• Open-graded; usually requires a seal coat.
• Aggregates consist of material passing 20 mm and retained on 6.3 mm sieve.

(c) Bituminous Concrete (AC)

• Dense graded premix, well compacted to form a high quality surface course.
• Consists of proportioned coarse and fine aggregates, mineral filler and bitumen; designed by methods such as the Marshall method.
• Typical IRC specification: 40 mm thick AC surface course; usual thickness range 40-75 mm.

(d) Sheet Asphalt (Rolled Asphalt)

• Dense sand-bitumen premix compacted to ~25 mm thickness; used as wearing course, commonly over cement concrete pavements for excellent riding surface.

Do you know? Sheet asphalt also protects joints in concrete pavements and reduces warping stresses by decreasing temperature gradients through the slab.

(e) Mastic Asphalt

• Mastic asphalt is a voidless, impermeable mix of bitumen, fine aggregates and filler; it absorbs vibrations and can self-heal cracks without bleeding.
• Suitable for bridge deck slabs; spread at ~200°C to thickness 25-50 mm; no rolling required.

Bituminous Construction Procedures

1. Surface Dressing

• Work is carried out in dry, clear weather with atmospheric temperature above about 16°C.

Specification of Materials

• Bitumen grades between 80/100 and 180/200 are commonly used; tar or cutback may also be used.
• Aggregate requirements: Los Angeles abrasion ≤ 35%; aggregate impact value ≤ 30%; flakiness index ≤ 25%; water absorption ≤ 1%; stripping at 40°C after 24 hr immersion ≤ 25% (CRRI test).

Construction Steps

1. Preparation of existing surface
2. Application of binder
3. Application of stone chippings
4. Rolling of first or final coat
5. Application of binder and chippings for second coat (if required)
6. Rolling of second coat
7. Finishing and opening to traffic

2. Penetration (Grouted) Macadam

• Recommended thicknesses: 50 mm and 75 mm compacted.

Material Specifications

• Bitumen grades used: 80/100, 60/70 and 30/40; road tars RT-4 and RT-5 may also be used.
• Aggregate tests: LA abrasion ≤ 40%; aggregate impact value ≤ 30%; flakiness index ≤ 25%; stripping at 40°C ≤ 25%; loss with sodium sulphate (5 cycles) ≤ 12%.

Do you know? Coarse aggregate required for 50 mm compacted thickness ≈ 0.06 m3 per 10 m2; for 75 mm compacted thickness ≈ 0.90 m3 per 10 m2.

Construction Steps

1. Preparation of existing surface
2. Spreading coarse aggregates
3. Rolling
4. Bitumen application
5. Spreading of flakey aggregates
6. Seal coat
7. Finishing
8. Opening to traffic after minimum 24 hours

3. Construction of Bituminous Macadam

• Premixed and laid immediately after mixing then compacted; open-graded - generally used as base or binder course.

Materials

• Bitumen grades: 30/40, 60/70 and 80/100 (or road tar, cutback, emulsion for cold mixes).
• Aggregates: low porosity with requirements for abrasion, impact, flakiness and stripping compatible with base course use.

Aggregates required for 10 m2: approximately 0.60-0.75 m3 for 50 mm and 0.90-1.0 m3 for 75 mm compacted thickness.

Construction Steps

1. Preparation of existing layer
2. Tack or prime coat application
3. Premix preparation
4. Placement
5. Rolling and finishing

4. Pre-mixed Bituminous Carpet

Materials

• Bitumen binder: typically 80/100 grade or road tar RT-3.
• Binder quantity for 2 cm thick carpet: prime coat on WBM surface 7.3-9.8 kg bitumen (or 12.2-14.64 kg road tar) per 10 m2; tack coat on blacktop 4.9-7.3 kg bitumen (or 7.3-9.8 kg tar) per 10 m2.
• Aggregate requirements: LA abrasion ≤ 35%; aggregate impact value ≤ 30%; flakiness index ≤ 30%; stripping ≤ 25%; water absorption ≤ 2.0%.

Construction Steps

1. Preparation of existing surface
2. Application of tack coat
3. Preparation and placement of premix
4. Rolling and finishing
5. Application of seal coat
6. Surface finishing and opening to traffic

5. Construction of Bituminous Concrete (AC)

• Layer thickness depends on traffic and quality of base course.

Material Specifications

• Binder - bitumen grade chosen by climate: 30/40, 60/70, or 80/100.
• Aggregates and filler - typical maximum values: aggregate impact ≤ 30%; LA abrasion ≤ 40%; flakiness index ≤ 25%; stripping ≤ 25%; soundness (sodium sulphate 5 cycles) ≤ 12%; magnesium sulphate ≤ 18%.

Bituminous Concrete Mix (Marshall Criteria)

• Marshall stability: minimum ~340 kg (value depends on design)
• Marshall flow: 8-16 (0.25 mm units)
• Voids in mix: 3-5%
• Voids filled with bitumen: 75-85%

Construction Steps

1. Preparation of existing base course
2. Application of tack coat
3. Preparation and placing of premix
4. Rolling
5. Quality control of bituminous concrete construction
6. Finished surface

Construction Of Cement Concrete Pavements

Cement concrete (CC) pavements provide excellent riding quality, appearance and long life. CC pavements may be constructed with or without a sub-base depending on soil type, design load and economics.

Purpose of Providing a Sub-base

• Provide a strong supporting layer
• Provide a capillary cutoff to prevent damage from mud-pumping
• Reduce required slab thickness and lower construction cost
• Increase service life of CC pavement

WBM is commonly used as sub-base in India; soil-stabilised layers are also used advantageously.

Types of Base Layers for CC Pavements

• Cement grouted layer - open-graded aggregates dry rolled then grouted with a sand-cement slurry (cement:sand ≈ 1:1.5 to 1:2.5).
• Rolled concrete layer - lean mix concrete placed and rolled similar to WBM construction; suitable for base course.

Modes of Slab Construction

• Alternate bay method - bays (slabs) are constructed alternately (X, Y, Z leaving X', Y' etc.) with gaps of about one week. Provides additional working convenience but increases the number of transverse joints and potential water collection between bays.
• Continuous bay method - slabs laid in sequence across the width; construction joints provided at the end of each day's work. Preferred where traffic can be diverted on the unworked half of the carriageway.

Plants and Equipment

• Wheelbarrows for short haul transport from mixers
• Floats for surface smoothing
• Straight edges for longitudinal surface checks
• Canvas belts for surface finishing before concrete hardens
• Fibre brooms for broom finishing (skid resistance)
• Edging tools for rounding edges at expansion joints and longitudinal edges

Material Specifications

Aggregates: maximum size should not exceed one-fourth of slab thickness.

Proportioning of Concrete

• Concrete should be proportioned to obtain a minimum modulus of rupture of 40 kg/cm2 at 28 days or compressive strength of ~280 kg/cm2 at 28 days (or as per design requirements).

Construction Steps for CC Pavement Slab

1. Preparation of subgrade and subbase - minimum modulus of subgrade reaction (plate bearing) should be ~5.54 kg/cm2; subgrade prepared and checked at least two days before concreting; saturate subgrade/subbase with water for 6-20 hours before placing concrete.
2. Placing of forms
3. Batching and mixing of materials - coarse and fine aggregates weigh-batched; cement measured by whole bags (50 kg bag or unit weight 1440 kg/m3).
4. Transporting and placing concrete
5. Compaction and finishing
6. Floating and straight-edging
7. Belting, brooming and edging - belt finish with two-ply canvas followed by broom finish before hardening
8. Curing

Curing Methods

• Initial curing - cover surface with saturated cotton or jute mats kept wet.
• Final curing - options include keeping soil saturated for 14 days or applying impervious membrane curing compounds that form a film within ~30 minutes.

The pavement is normally opened to traffic after the concrete attains required strength or after 28 days of curing.

Construction Of Joints In Cement Concrete Pavements

Joints are provided for expansion, contraction and warping of slabs due to temperature variations. Diurnal temperature changes cause differential expansion between top and bottom fibres producing warping; restraint by slab weight develops warping stresses which are highest at interior regions.

Types of Joints

• Expansion joint
• Contraction joint
• Warping (hinged) joint
• Construction joint

Transverse Joints - Expansion Joints

• Expansion joint spacing in India: 50-60 m for smooth interface laid in winter; 90-120 m for smooth interface laid in summer; for rough interface spacing up to ~140 m may be used.
• Typical gap width: 20-25 mm.
• Wheel loads induce high stresses at edges/corners; load transfer across transverse joints is often provided using dowel bars projecting longitudinally into adjoining slab for about 60 cm.
• Design assumes about 40% of wheel load transferred by a group of dowel bars; dowel spacing is typically ~30 cm; dowel lengths vary from about 40 cm to 73 cm depending on diameter.

Contraction Joints

• Contraction joints are spaced closer than expansion joints; load transfer is provided mainly by aggregate interlock at joint faces.
• Maximum spacing: unreinforced CC slabs ~4.5 m; reinforced slabs of 200 mm thickness may be spaced up to ~14 m.
• Some agencies recommend dowel bars fully bonded in concrete for added safety.

Warping Joints

• Warping or hinged joints relieve warping stresses; longitudinal joints with tie bars may serve this function. If expansion and contraction joints are properly designed, separate warping joints are often unnecessary.

Longitudinal Joints

• Longitudinal joints are provided when pavement width exceeds ~4.5 m to accommodate differential edge shrinkage/swelling and to prevent longitudinal cracking.
• They act as a hinge and keep adjacent slabs at same level; IRC recommends plain butt joints with tie bars.
• Example tie bar provisions (for 200 mm slab): 10 mm deformed tie bars 35 cm long or plain bars 45 cm long at 45 cm spacing; or 12 mm deformed bars 40 cm long or plain bars 55 cm long at 64 cm spacing. For 250 mm slabs, tie bar diameters 10-14 mm of suitable lengths at spacings 30-62 cm are used.
• Provide transverse joints in same alignment across the longitudinal joint to avoid sympathetic cracks.

Joint Filler and Sealer

• Water infiltration damages subgrade and causes mud-pumping; stone grit entering joints reduces effective joint width and can cause spalling.
• Joint fillers: soft wood, impregnated fibreboard, cork or cork bound with bitumen.
• Sealing compounds: bitumen, rubber-bitumen or air-blown bitumens (less temperature susceptible).

Reinforced Concrete Pavements

• Use greater reinforcement in the longitudinal direction; reinforcement is placed at mid-depth or toward the top of the slab for better performance.

Construction Of Soil-stabilized Roads

Common methods of soil stabilisation:

• Mechanical soil stabilisation
• Soil-cement stabilisation
• Soil-lime stabilisation
• Soil-bitumen stabilisation

Mechanical Soil Stabilisation

• Suitable for granular soils.
• Proportioning of aggregate and soil is done to obtain a mechanically stable mix that attains maximum dry density.
• Stability of the mix is increased by attaining high dry densities; proportioning methods include triangular charts or Rothfuch's method.

Mix Design in Mechanical Stabilisation

• Consider gradation, density, index properties and stability; gradation is the most important factor.
• Theoretical gradation for maximum density follows a relationship where P (percent finer than diameter d) is a function of d, the largest particle size D and a gradation index n (typical n = 0.3-0.5).

Here P = percentage finer than diameter d (mm); D = largest particle diameter (mm); n = gradation index (0.3-0.5 depending on particle shape).

Soil-Cement Stabilisation

• Intimate mix of soil, cement and water compacted to form a strong base course.
• In granular soils, bond develops between hydrated cement and soil particles; in fine-grained soils plasticity is reduced and a matrix forms encapsulating clay lumps.
• Not suitable as a wearing course due to poor abrasion resistance; a bituminous wearing course is placed over the stabilized base.

Soil-Lime Stabilisation

• Used as a modifier for clayey soils or as a binder. Lime reduces plasticity index, makes clay friable and reduces affinity for water.
• Lime imparts some binding action to granular soils and is suitable for sub-base or base in low traffic pavements; not suitable as surface course.

Stabilisation of Black Cotton Soils

• Black cotton (BC) soils are highly clayey and contain montmorillonite, which is highly expansive.
• Effective stabilisation usually requires lime with suitable additives; cement requirements alone are often too high and uneconomic.

Stabilisation of Desert Sand

• Soil-bitumen stabilisation is generally used in desert sands.
• Bituminous emulsions are promising for stabilising desert sands because of ease of application and performance in arid climates.

Checks, Quality Control And Final Notes

• Field control tests (moisture content and dry density) are essential for embankment and base construction quality control.
• For WBM and bituminous works, check surface evenness (straight edge), camber profile and rectify undulations as per permissible limits.
• For bituminous works respect temperature and weather limitations (e.g., surface dressing above ~16°C, dry weather for many operations).
• For concrete pavements ensure proper curing (initial and final) to achieve design strength and durability.