road construction works

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BASIC KNOWLEDGE IN ROADCONSTRUCTION

Chungdu TsheringEngineer, CDB, MoWHS


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Types of Road in Bhutan

1. National Highways2. Dzongkhag Roads3. Farm Roads


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1. National Highways

a. Asian Highway (Currently the existing Phuentsholing-ThimphuHighway)

b. Primary National Highway (existing East-West Highway)c. Secondary National Highway (Currently District Roads)

Carriageway3500

Shoulder 1500

Shoulder 1500

L-Drain1000

Sub base = 190mmBase Course = 150mm

Hard Shoulder

Compacted Granular Soil Soling

Secondary National Highway

Subgrade CBR = 7%

Carriageway6500

Shoulder 1500

Shoulder 1500

L-Drain1000


Hard Shoulder


Primary National Highway

Subgrade CBR = 7%

50mm DBM + 25mm AC

25mm PMC


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2. Dzongkhag Roads Currently feeder Roads Connects a Dzongkhag centre and a Dungkhag Centre etc.

Carriageway3500

Shoulder 500

Shoulder 500

L-Drain600


Hard Shoulder


Dzongkhag Road

Subgrade CBR = 7%


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3. Farm Roads Roads that link farmland areas/villages.

Carriageway3500

Shoulder 500

Shoulder 500

L-Drain600


Hard Shoulder


Farm Road

Subgrade CBR = 7%

Note: If the traffice is less than 10-15 vpd, single layer base course should sufice


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WHAT

WE DOIN ROAD CONSTRUCTION


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MAJOR ACTIVITIES

1. FORMATION CUTTIN G2. SUB-GRADE PREPARATION3. BASE COURSE & BLACK TOPPING

4. SHOULDER5. PERMANENT WORKS6. BRIDGES


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1. FORMATION CUTTING

SLOPEGRADIENTGEOMETRICDISPOSAL OF SPOIL


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2. SUB-GRADE PREPARATION

In order to maintain stable and durable sub-grade, uniformconsolidation to be incorporatedSub-grade act as a cushion for other layers i.e. In order to

achieve durable road sub-grade should be strong

.Maintain proper Camber


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SUB-GRADE PREPARATION

CAMBER


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3. BASE COURSE & BLACK TOPPING

Type I (Old) Base course = 150 + 100 = 250mm thickness 150mm = 40-63mm, (Rolling) 100mm = 20-50mm, (Rolling)

Premix = 25mm + blinding material (Rolling by applying water) Sand Seal coat Resurfacing: 20mm

Type II (New) Granular Sub-Base (GSB) coarse graded (70mm below) Wet Mix Macadam (WMM) (40 mm, 20 mm, 10 mm & Soil) mix

with water Dense Bitumen Macadam (DBM) 20mm + Bitumen Asphalt Concrete 10mm + Bitumen

Thickness depends upon the actual design for a road


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Sub-Grade Preparation

Base Course: 150mm ( 40-63mm),Rolling

Base Course: 150mm ( 20-50mm),Rolling

Premix: 10mm + bitumen, Rollingby applying water

Sand Seal Coat

Base Course & Type - I


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Sub-Grade Preparation

Granular Sub Grade ( 70mm below),rolling

Wet Mix Macadam (WMM), 10 to40mm plus soil with water & rolling

Dense Bitumen Macadam (DBM) 20mm + Bitumen

Asphalt Concrete 10mm +Bitumen

Base Course & Type - II


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TYPE - I


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TYPE - II


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4. SHOULDER:

A hard area at the side of a main road, especially amotorway, where a driver can stop if there is a seriousproblem

Shoulder should be strong enough to resist any types

of vehicle

Maintain proper compaction as per the design

Width and thickness should be as per the specification


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SHOULDER


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PERMANENT WORKS

RETAINING WALLBREAST WALLRCC WALLCULVERTDRAIN


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Breast Wall


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RCC Wall


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Culverts


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Culverts


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CATCH PITCATCH PIT


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3. BRIDGE CONSTRUCTIONRCC BRIDGESTEEL BRIDGEBAILEY BRIDGEWOODEN BRIDGE


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RCC Bridge


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Steel Bridge


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Bailey Bridge


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Wooden Bridge


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MATERIALS REQUIRED IN ROAD

CONSTN. CEMENT SAND BOULDER AGGREGATES (different sizes) STEEL MESH BITUMEN GEO-TEXTITLE RCC HUME PIPES


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CONSTRUCTED WITHOUT SPECIFICATION


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WE BUILD

GOOD & DURABLE ROAD


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WE PROVIDE TO ROAD USERS

COMFORT & SAFE RIDING LESS OPERATIONAL COST IN REASONABLE TIME


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FOR THE COUNTRY

BOOST UPCOUNTRYs SOCIO

-ECONOMYDEVELOPMENT


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