Construction Mirror Industry Features Details

ROAD CONSTRUCTION & HIGHWAYS:PAVING A BETTER WAY

August 19, 2019

BASIC CONCEPTS with LATEST TRENDS

Road transport is one of the most common mode of transport. Roads in the form of trackways, human pathways etc. were used even from the pre-historic times. Modern highways are known for their high capacity, efficiency, and planned construction. Highway networks are very important for the growth of a region. Highways open new trade routes and almost every industrial region in the world is connected to the major highway network system of that particular country.

The National Highways network of India is a network of trunk roads that is owned by the Ministry of Road Transport and Highways. It is constructed and managed by the National Highway Authority of India (NHAI), the National Highways and Infrastructure Development Corporation (NHIDCL), and the public works departments (PWDs) of state governments. NHAI was established by the National Highways Authority of India Act, 1988.


MATERIALS USED FOR ROAD CONSTRUCTION

Highway construction materials are selected on the basis of the type of highway, known and projected traffic density, and the climatic conditions of the region. At some places we manage with bitumen (asphalt) only, however, at some place concrete roads are required. Modern age engineers emphasize the use of eco-friendly methods to construct roads, bridges, and pavements. Maximizing the use of recycled waste products is a smart new trend that has actually helped in making better roads and highways- without doing much damage to our environment. 

1.Sub Grade Soil

Soil is an accumulation or deposit of earth material, derived naturally from the disintegration of rocks or decay of vegetation, that can be excavated readily with power equipment in the field or disintegrated by gentle mechanical means in the laboratory. The supporting soil beneath pavement and its special under courses is called sub grade. Undisturbed soil beneath the pavement is called natural sub grade. Compacted sub grade is the soil compacted by controlled movement of heavy compactors.

The desirable properties of sub grade soil as a highway material are: Stability, Incompressibility, Permanency of strength, Good drainage andEase of compaction.The tests used to evaluate the strength properties of soils may be broadly divided into three groups:

  • Shear tests
  • Bearing tests
  • Penetration tests

2. Stone Aggregates:

Stone aggregate, or mineral aggregate, as it is called, is the most important component of the materials used in the construction of roads. These aggregates are derived from rocks, which are formed by the cementation of minerals by the forces of nature.

Stone aggregates are invariably derived by breaking the naturally occurring rocks to the required sizes. They are used for granular bases, sub-bases, as part of bituminous mixes and cement concrete; they are also the primary component of a relatively cheaper road, called water-bound macadam.

3. Bituminous Materials:

Bitumen was used as a bonding and water-proofing agent thousands of years ago. However, the use of bitumen for road-making picked up only in the nineteenth century. As the quest for fuels like petroleum to run automobiles grew and the distillation of crude oil emerged as a major refining industry, the residues known as bitumen and tar found increasing use in constructing bituminous surfaces, which provided superior riding surface.

4. Cement, Cement Mortar and Cement Concrete:

Cement concrete is a versatile material which has revolutionised civil engineering construction during the twentieth century. A fresh cement concrete mix consists of cement, mineral aggregates (coarse aggregate and fine aggregate), and water.

A well-designed cement concrete mix sets and hardens due to the binding property of the cements, forms a mix with minimum void space and on curing with water, provides a strong, stable and durable pavement for a highway, resisting repetitive impact from wheel loads and also withstanding adverse environmental conditions.

Thus, a cement concrete pavement is the most superior highway construction primarily from the point of view of strength and durability. The ingredients of the concrete mix, viz., the coarse aggregate (broken stone) and fine aggregate (sand) have to be selected carefully to satisfy the desirable properties for concrete-making. Potable water is generally considered satisfactory making cement concrete.

Cement is used also as an additive to soil to produce soil-cement used as the primarily material in the construction of low-cost roads.

 

ROAD CONSTRUCTION PROCESS:

Steps included in road construction process are as follows:

STEP 1 :Clearing and Excavation

  • The area on which the road is going to be built on must be cleared of all vegetation, which requires the removal of trees, shrubs and bushes.
  • Excavation vehicles will also dig up and remove rocks and stones from the future road's pathway. To prevent the cleared land from erosion, control devices, including fences, ditches and basins are installed.

STEP 2: Mounting

  • The road takes shape as diggers, excavation plant machinery and bulldozers mount dirt and soil over the area where the future pathway will run.
  •  The surface is then leveled and smoothed by graders. Culverts and drains, consisting of large concrete pipes, are laid to prevent the road from flooding by leading away groundwater, sewage or stormwater.

STEP 3: Fine Grading

  • Fine grading requires construction workers to prepare the surface by leveling it according to plans provided by structural engineers.
  • Fine grading requires manual labour and digging as well as grading plant machinery, also called graders. To make the grading last, it is stabilized with limestone or concrete.

STEP 4: Aggregate Base

  • After another grading of the surface, the aggregate base course is laid. Aggregate base is made of crushed stone or gravel, and it is placed evenly on the road surface.
  •  If the road is in a town or city, a curb for the pavement and the gutter will be constructed straight after the gravel is placed on the surface. The road is then fine graded again.

STEP 5: Asphalt Paving

  • Once the gravel has been distributed evenly, the asphalt can be poured. Asphalt is a mixture of a petroleum byproduct, an aggregate base material and a sticky, gluelike substance called bitumen.
  •  Depending on the expected traffic on the road, up to four layers of asphalt can be placed on top of each other. The asphalt usually is produced and mixed in large plants after the engineer's specifications.
  • The hot asphalt is filled into trucks that transport the material to the construction site where it will be poured immediately. Before the last layer of asphalt is poured, the sidewalks and gutters have to be finished.
  • The construction work is concluded by placing the appropriate road signs at the places specified by planners and the application of road markings.

 

LATEST TRENDS

India has second largest road networks in the world, spanning a total of 5.5 million kilometres (kms).

The private sector has emerged as a key player in the development of road infrastructure in India. Increased industrial activities, along with increasing number of two and four wheelers have supported the growth in the road transport infrastructure projects. The government’s policy to increase private sector participation has proved to be a boon for the infrastructure industry with a large number of private players entering the business through the public-private partnership (PPP) model.

Investments in the road sector increased thrice in the last five years to Rs 1.58 lakh crore in 2018-19. The investments have been financed from budgetary support, internal and extra-budgetary resources (IEBR) and private sector. While budgetary support accounted for 48 per cent of the investments in 2018-19, private investments accounted for 14 per cent.

The road sector accounts for about 3.14 per cent of India's gross value added (GVA) and around 69 per cent of India's freight traffic and 90% of passenger traffic. GVA is the measure of the value of goods and services produced in an area, industry or sector of an economy.

Major road projects taken up in the last five years include the Eastern Peripheral Expressway, Delhi-Meerut Expressway and Dhola-Sadiya Bridge. Eastern Peripheral Expressway has been constructed with the objective to de-congest the national capital by providing an alternate route to traffic not destined for Delhi.

With the Government permitting 100 per cent foreign direct investment (FDI) in the road sector, several foreign companies have formed partnerships with Indian players to capitalise on the sector's growth. Cumulative FDI in construction development^ since April 2000 stood at US$ 25.05 billion as of March 2019. MAIF 2 became the first largest foreign investment in Indian roads sector under TOT mode worth Rs 9,681.5 crore (US$ 1.50 billion). As of November 2018, total length of projects awarded under Bharatmala Pariyojana (including residual NHDP works) was 6,460 kms for a total cost of Rs 1.52 trillion (US$ 21.07 billion). The total amount of investments* are estimated to reach Rs 1.58 trillion (US$ 2.25 billion) in FY19.

The Ministry of Road Transport and Highways has fixed a target for construction of 10,000 km national highways in FY19. The length of national highways constructed reached 6,715 km at a pace of 24.42 kms per day between April-December 2018. The Government of India aims to construct 65,000 km of national highways at the cost of Rs 5.35 lakh crore (US$ 741.51 billion) by 2022.

Achievements

Following are the achievements of the government in the past four years:

  • The total national highways length increased to 122,434 kms in FY18 from 92,851 kms in FY14.
  • The length of national highways awarded increased to 51,073 kms between FY15-FY18 from 25,158 kms in FY11-FY14.
  • The construction of national highways increased to 28,531 kms between FY15-FY18 from 16,505 kms between FY11-FY14.
  • The construction of national highway per day increased to 26.9 kms per day in FY18 from 11.6 kms per day in FY14.

 

Union Budget 2019:

In the last five years, the government has made huge investments in the road sector with total investment increasing more than three times from Rs 51,914 crore in 2014-15 to Rs 158,839 crore in 2018-19.
  • In the last five years, the government has made huge investments in the road sector with total investment increasing more than three times from Rs 51,914 crore in 2014-15 to Rs 158,839 crore in 2018-19, according to official data.
  • Taking cues from past trends, it is expected that government will pump in huge investment into the roads and highways sector over the next five years.
  • Ministry of Road Transport and Highways (MORTH) had declared 2018-19 as the 'Year of Construction', and had made constant efforts to expand and upgrade the network of National Highways in the country as a result of which road construction grew at 30 km per day in 2018-19 as compared to 12 km per day in 2014-15.
  • The Bharatiya Janata Party (BJP) in its election manifesto had promised to make Rs 100 lakh crore investment in the infrastructure sector by 2024. It spoke about constructing 60,000 kms of National Highways in the next five years. It also added that it will complete the Phase-1 of Bharatmala Project expeditiously.

CRISIL REPORT ON ROAD CONSTRUCTION/HIGHWAYS

  • CRISIL Research expects overall project awarding in the roads and highways sector in fiscal 2019 to be in the range of 4,000-4,500 km.
  • The National Highways Authority of India (NHAI), the nodal agency, had awarded ~7,400 km in fiscal 2018, with most of the projects awarded in March. In the first half of fiscal 2019, the NHAI awarded about 300 km, most of which was via HAM (Hybrid Annuity Model).
  • In fiscal 2020, based on the balance of share of tenders that will remain unawarded in fiscal 2019 and additional tenders floated by the NHAI in the next fiscal, the awarding is expected to improve marginally to 4,500-5,000 km.

 

 

 

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