Unit – 1
Highway Development & Planning
- India has a vast country the economic prosperity of the country depends upon its product and economic transportation to the marketing centers.
- The roads also play a important role in the defense of our country as well as in cultural progress.
- India is a country of village but more attention is given to the roads of national importance than the district or village roads.
- Large quantity of the perishable agricultural product of India goes waste on account of delay in reaching market.
- Such things can be avoided by providing faster and lager transport facilities in rural areas.
- They offer humans and automobiles to go back and forth a extensive variety of places and assist them to attain their vacation spot with none hiccups.
- Road shipping is the technique of transporting items or humans from one vacation spot to the alternative through roads.
Key takeaway:
- The roads also play a important role in the defense of our country as well as in cultural progress.
- India is a country of village but more attention is given to the roads of national importance than the district or village roads.
- Large quantity of the perishable agricultural product of India goes waste on account of delay in reaching market.
(i) Planning a highway network for safe, efficient and fast movement of people and goods.
(ii) Keeping the overall cost of construction and maintenance of the roads in the network to a minimum.
(iii) Planning for future development and anticipated traffic needs for a specific design period.
(iv) Phasing road development programmers from considerations of utility and importance as also of financial resources.
Road development plans:
a) Nagpur Road Plan
- The Second World War saw a rapid growth in road traffic and this led to the deterioration in the condition of roads.
- To discuss about improving the condition of roads, the government convened a conference of chief engineers of provinces at Nagpur in 1943. The result of the conference is famous as the Nagpur plan.
- A twenty-year development programmed for the period (1943-1963) was finalized. It was the first attempt to prepare a co-ordinate road development programmed in a planned manner.
- The roads were divided into five classes:
1) National highways which would pass through states, and places having national importance for strategic, administrative and other purposes.
2) State highways which would be the other main roads of a state.
3) District roads which would take traffic from the main roads to the interior of the district. According to the importance, some are considered as major district roads and the remaining as other district roads.
4) Village roads which would link the villages to the road system.
5) The committee planned to construct 2 lakh kms of road across the country within 20 years.
6) One of the objectives was that the road length should be increased so as to give a road density of 16kms per100 sq.km.
b) Bombay Road plan & 3rd20-Year Road Plan
Bombay Road Plan
- The length of roads was under the Nagpur plan was achieved by the end of it, but the road system was deficient in many respects.
- Accordingly, a 20-year plan was drafted by the roads wing of government of India, which is popularly known as the Bombay plan.
- The highlight of the plan was:
It was the second-year road plan 1961 to 1981.
The total road length targeted to construct was about 10 lakhs.
Rural roads were given specific attention.
They suggested that the length of the rod should be increased so as to give a road density of 32 km per hundred square kilometers.
The construction of 1600 km of expressways was also then included in the plan.
3rd 20-Year Road Plan (Luck now)
- This plan has been prepared keeping in view the growth pattern envisaged in various held by the turn of the century. Some of the salient features of this plan are as given below:
- This was the third 20-year road plan (1981-2001). It is also called Luck now road plan.
- It aimed at constructing a road length of 12 lakh kilometers by the year 1981 resulting in a road density of 82kms/100 sq.km.
- The plan has set the target length of NH to be completed by the end of seventh, eighth and ninth five-year plan periods.
- It aims at improving the transportation facilities in villages, towns etc. such that no part of country is farther than 50 km from NH.
- One of the goals contained in the plan was that expressways should be constructed on major traffic corridors to provide speedy travel.
- Energy conservation, environmental quality of roads and road safety measures were also given due importance in this plan.
Key takeaway:
- The Second World War saw a rapid growth in road traffic and this led to the deterioration in the condition of roads.
1. Rectangular pattern
- In this pattern, the whole area is divided into rectangular blocks of plots, with streets intersecting at right angles.
- The main road which passes through the center of the area should be sufficiently wide and other branch roads may be comparatively narrow. The main road is provided a direct approach to outside the city. This pattern has been adopted in the city roads of Chandigarh.
Advantages:
1) The square plots can be similarly divided into small square blocks for production of homes positioned lower back to lower back, having roads on their front.
2) In this sample has been followed for the metropolis roads.
3) The production and protection of roads of this sample is relatively easier.
Limitations:
- This sample isn't very a lot handy due to the fact on the intersections, the motors face every other.
2. Radial or Star and block Pattern
- In this pattern, the complete region is split right into a community of roads radiating from the enterprise outwardly. In among radiating important roads, the built-up region can be deliberate with square block.
Advantage:
1) Reduces degree of congestion on the number one bottleneck location.
2) Prevents site visitors from gaining access to neighborhood glide routes withinside the course of the occasion venue that function in want of egress site visitors glide.
3) If one is block then different aspect site visitors can move.
Limitations:
- Proves mainly powerful if two-lane ramp site visitors does now no longer should merge at downstream stop of ramp.
3. Radial or Star and Circular Pattern
- In this system, the primary radial roads radiating from vital commercial enterprise location are linked collectively with concentric roads.
- In those areas, boundary with the aid of using adjoining radial roads and corresponding round roads, the built-up location is deliberate with a curved block system.
Advantages:
1) At conventional intersections with forestall symptoms and symptoms or site visitors indicators, a number of the maximum not unusual place styles of crashes are right-angle, left-turn, and head-on collisions. These styles of collisions may be intense due to the fact cars can be touring through the intersection at excessive speeds. With round sample, those styles of probably critical crashes basically are removed due to the fact cars journey withinside the equal direction.
2) Installing round sample in region of site visitors indicators also can lessen the chance of rear-stop crashes.
Limitations:
1) Approach roads ought to be sufficiently curved, some distance sufficient earlier of round pattern, to lessen car speeds of coming into drivers.
2) Traffic signs, pavement markings, and lighting fixtures ought to be ok in order that drivers are conscious that they may be coming near a roundabout and they ought to lessen their tour speed.
4. Radial or Star and Grid Pattern
- Change in direction, and due to the fact road styles are the maximum enduring bodily detail of any layout, it is able to probably make contributions to systematic web website online making plans and, consequently, merits a more in-depth look.
- Though the community is totally interconnected, north-south motion turns into circuitous, indirect, and inconvenient, making riding an not likely desire and vividly illustrating that interconnections through itself is inadequate to facilitate motion.
Advantages:
1) Keep vehicular site visitors secure with a excessive share of 3-manner intersections.
2) Reduce cut-through site visitors with the aid of using comparable or different means.
3) Improve site visitors go with the drift in each guidelines the usage of Savannah’s mobile structure. 4) Improve land use performance and unit density.
Limitations:
1) Islands keeping apart the technique and go out lanes, called splitter islands, must expand some distance enough.
2) Traffic signs, pavement markings, and lights must be good enough in order that drivers are conscious that they must lessen their tour speed.
5. Hexagonal Pattern
- In this pattern, the whole location is supplied with a community of roads formatting hexagonal figures.
- At every nook of the hexagon, 3 roads meet the built-up location boundary with the aid of using the edges of the hexagons is similarly divided in appropriate sizes.
Advantages:
Three roads meet the built-up location boundary with the aid of using the edges of the hexagons.
Limitations:
Traffic signs, pavement markings, and lighting fixtures need to be ok in order that drivers are conscious that they need to lessen their tour speed.
6. Minimum Travel Pattern
- In this street pattern, metropolis is contented through quarter middle, suburban middle and community middle through the street which required minimal to attach the metropolis middle.
- Legend: City middle — encircled dot- quarter middle — * suburban middle — * community middle — * illustration of a Minimum Travel metropolis
Advantages:
Those kinds of probably severe crashes basically are eliminated.
Limitations:
1) Traffic signs, pavement markings, and lighting fixtures need to be ok in order that drivers are conscious that they need to lessen their journey speed.
2) Intersections may be particularly tough for older drivers.
Key takeaway:
- The main road which passes through the center of the area should be sufficiently wide and other branch roads may be comparatively narrow. The main road is provided a direct approach to outside the city. This pattern has been adopted in the city roads of Chandigarh.
Highway making plans entails the estimation of cutting-edge and destiny visitors volumes on a avenue network. The Highway making plans is likewise a simple want for the Highway development. Highway engineers try to are expecting and examine all viable civil influences of toll road systems.
Financing
- Developed nations are continuously confronted with excessive renovation value of getting older transportation highways.
- The boom of the motor automobile enterprise and accompanying monetary boom has generated a call for for safer, higher performing, much less congested highways.
- The boom of commerce, instructional institutions, housing, and protection have in large part drawn from authorities budgets withinside the past, making the financing of public highways a challenge
- The multipurpose traits of highways, monetary environment, and the advances in toll road pricing era are continuously converting. Therefore, the procedures to toll road financing, management, and renovation are continuously converting as well.
Environmental impact assessment
- The monetary increase of a network depends upon dual carriageway improvement to beautify mobility.
- However, improperly planned, designed, built, and maintained highways can disrupt the social and monetary traits of any length network. Common negative influences to dual carriageway improvement encompass harm of habitat and bio-diversity, advent of air and water pollution, noise and vibration generation, harm of herbal landscape, and the destruction of a network's social and cultural structure. Highway infrastructure need to be built and maintained to excessive traits and standards.
Highway safety
- Highway systems generate the highest price in human injury and death, as nearly 50 million persons are injured in traffic accidents every year, not including the 1.2 million deaths. Road traffic injury is the single leading cause of unintentional death in the first five decades of human life.
Key takeaway:
The Highway making plans is likewise a simple want for the Highway development. Highway engineers try to are expecting and examine all viable civil influences of toll road systems.
1. Map study
In the beginning, diverse information withinside the styles of maps, aerial photographs, charts or graphs, etc. are collected. Topographical maps are completed with the aid of using the survey of India are to be had with 15 m to 30 m contour interval. Maps display the diverse topographical capabilities like river, hills, and valleys. With the right map examine on the office, it's miles feasible to acquire the primary information to restore the alignment of roads.
2. Reconnaissance survey
A subject survey birthday celebration examines the overall man or woman of a reasonably extensive stretch of land among the terminal stations withinside the subject, alongside the proposed opportunity alignments marked at the map is referred to as reconnaissance survey. In this survey, easy survey contraptions like a prismatic compass, Abney level, tangent clinometer, barometer, etc. can be used to gather extra info rapidly.
Objectives:
To gather the info of obstruction alongside the course which aren't to be had withinside the map. For example, Valleys, ponds, lakes, marshy land, ridge, hills, everlasting structure, etc.
To gather geological capabilities of the sector. For example, Soil kind alongside the course from the sector identity checks and the remark required for basis paintings of bridges and production of street pavements.
To gather statistics concerning the supply of neighborhood production material, water, and labor.
To decide the approximate values of a gradient, duration of gradients and radius of curves of change alignments. To discover the compulsory factors alongside the opportunity routes.
To decide an approximate estimate of the overall value of production of the street alongside every course.
3. Preliminary survey
Definition
The artwork of locating the info of opportunity alignments located appropriate at some stage in the reconnaissance survey is referred to as initial survey. In a initial survey, the survey devices for use are chain type, prismatic compass, leveling instrument, aircraft desk theodolite.
OBJECTS
1] To survey alongside the numerous alignments located after the reconnaissance and to acquire all vital bodily records and info of topography, drainage, and soil.
2] To examine the distinctive proposals in view of the necessities of appropriate avenue alignment.
3] To estimate the fee of building the street consisting of bridges and different production components alongside every opportunity alignment of the street.
4] To finalize the first-class alignment from production, maintenance, and site visitors operation factor of view.
4. Location Survey
Definition
The specified exam of the sector alongside the alignment ultimately encouraged throughout the initial survey is referred to as Location survey. In this survey units used are theodolite, level, aircraft table, tape, etc.
OBJECTS
(i) The alignment finalized on the layout workplace after the initial survey is to be first positioned on the sector with the aid of using setting up the centerline.
(ii) The specified survey must be accomplished for gathering the records essential for the coaching of plans and production information for the toll road project.
(iii) To decide the value of the full avenue project.
5. Engineering Surveys for Highway
When the selection of final alignment or final centerline is done with the help of a planning survey, the next part is to perform an engineering survey.
The function of the significant line of the dual carriageway or the format of the deliberate dual carriageway line at the floor is referred to as Highway Alignment. Highway Alignment is typically phrased as sorts on Highway plans
Horizontal Alignment:
This covers the horizontal path of the road either it’s straight or curved or both. Top view of road alignment gives horizontal alignment of the road.
Vertical Alignment:
This deals with the gradients, slopes and levelling of the ground.
Perspective view or front view or side view of the road alignment makes you understand about Vertical alignment.
Key takeaway:
To gather the info of obstruction alongside the course which aren't to be had withinside the map. For example, Valleys, ponds, lakes, marshy land, ridge, hills, everlasting structure, etc.
Highway alignments requirements:
1. Short
The alignment should be short so as to make the road project economical. To meet this requirement, the alignment should be as straight as possible.
2. Easy
The alignment should be such that it is easy to construct and maintain the road with minimum problems.
3. Safe
The alignment should be safe for traffic operation. It should be safe for the construction and maintenance of the road.
4. Economical
The alignment should be economical in its cost of construction, maintenance and traffic operations.
5. Utility
The alignment should be such that it would offer maximum utility by serving maximum population and products.
6. Natural Aspects
The alignment should have good natural aspect.
Key takeaway:
The alignment should be safe for traffic operation. It should be safe for the construction and maintenance of the road.
The following steps are involved in finalizing the Highway alignment& preparing the project:
- Map Study:
It is the very first step of highway survey.
In this, we use a topographic map of the area under consideration, which can be availed from the Survey of India. Using the map, we can propose different alternatives of the road alignment.
The topographic map usually has contour intervals of around 30 m to 40 m.
We can get the details of the natural as well as man-made land features of the area using this map, and based on this we can then suggest a number of options for the road alignment.
These alternative route options are further studied in detail in the later steps.
- Reconnaissance Survey:
This is done to examine the general character of the area for deciding the most feasible routes for detailed studies.
Basic surveying instruments are used in the reconnaissance survey.
Following data is obtained from Reconnaissance Survey:
- Valley, pond, lakes and other features that may not be present on the topographical map.
- A number of cross drainage structures, High Flood Level (HFL), Natural Ground Level etc.
- Values of the gradient, the length of gradients and radius of the circular curve.
- Soil type along the routes from field identification tests and observation of the geological features.
- Sources of construction materials.
- Preliminary Survey:
This is carried out to collect all the physical information which is necessary in connection with the proposed highway alignment. This work consists of:
- Primary traverse survey
- Study of topographical features
- Leveling work
- Drainage studies & hydrological data
- Soil survey
- Material survey
- Determination of final center line
This may be done using:
- Conventional Approach: This includes using conventional survey instruments.
- Modern Rapid Approach: This is done by aerial photography.
1. Properties of sub grade:
- 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.
Desirable Properties of Sub grade Soil
- Stability
- Incompressibility
- Permanency of strength
- Minimum changes in volume and stability under adverse conditions of weather and groundwater
- Superior drainage
- Ease of compaction
Soil Types
Gravel | Sand | Silt | Clay | ||||||
| Coarse | Medium | Fine | Coarse | Medium | Fine | Coarse | Medium | Fine |
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| 0.6mm 0.2mm | 0.02mm 0.006mm | 0.0006mm 0.0002mm | ||||||
2mm | 0.06mm | 0.002mm |
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- Gravel: These are coarse materials with particle size under 2.36 mm with little or no fines contributing to cohesion of materials.
- Moorum: These are products of decomposition and weathering of the pavement rock. Visually these are similar to gravel except presence of higher content of fines.
- Silts: These are finer than sand, brighter in color as compared to clay, and exhibit little cohesion. When a lump of silty soil mixed with water, alternately squeezed and tapped a shiny surface makes its appearance, thus dilatancy is a specific property of such soil.
- Clays: These are finer than silts. Clayey soils exhibit stickiness, high strength when dry, and show no militancy. Black cotton soil and other expansive clays exhibit swelling and shrinkage properties. Paste of clay with water when rubbed in between fingers leaves stain, which is not observed for silts.
Key takeaway:
- 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.
- Sub grade soil is an integral part of the road pavement structure as it provides the support to the pavement from beneath.
- The main function of the sub grade is to give adequate support to the pavement and for this the sub grade should possess sufficient stability under adverse climatic and loading conditions. Therefore, it is very essential to evaluate the sub grade by conducting tests.
- The tests used to evaluate the strength properties of soils may be broadly divided into three groups:
- Shear Tests
- Bearing Tests
- Penetration Tests
- Shear Tests: are usually carried out on relatively small soil samples in the laboratory.
In order to find out the strength properties of soil, a number of representative samples from different locations are tested.
Some of the commonly known shear tests are direct shear test, tri axial compression test, and unconfined compression test.
2. Bearing Tests: are loading tests carried out on sub grade soils in-situ with a load bearing area.
The results of the bearing tests are influenced by variations in the soil properties within the stressed soil mass underneath and hence the overall stability of the part of the soil mass stressed could be studied.
3. Penetration Tests: may be considered as small scale bearing tests in which the size of the loaded area is relatively much smaller and ratio of the penetration to the size of the loaded area is much greater than the ratios in bearing tests.
The penetration tests are carried out in the field or in the laboratory.
Key Takeaways:
- Undisturbed Soil: - An undisturbed sample is one where the condition of the soil in the sample is close enough to the conditions of the soil in-situ to allow tests of structural properties of the soil to be used to approximate the properties of the soil in-situ.
- Disturbed Soil: - Soil that has been changed from its natural condition by excavation or other means.
1. Aggregates
- Aggregates form the major portion of the pavement structure, bear stresses occurring on the roads and have to resist wear due to abrasive action of traffic.
- Aggregates are also used in flexible as well as in rigid pavements. Therefore, the properties of aggregates are of considerable importance to highway.
- The aggregates are specified based on their grain size, shape, texture and gradation.
- Based on the strength property, the coarse aggregates maybe divided as hard aggregates or soft aggregates (Moorum, kankar, laterite, brick aggregates).
Desirable Properties of Road Aggregates
1) Strength:
The aggregates to be used in road construction, particularly the aggregates used in the wearing course of the pavement should be sufficiently strong/ resistant to crushing to withstand the high stresses induced due to heavy traffic wheel loads.
2) Hardness:
The aggregates used in the surface course are subjected to constant rubbing or abrasion due to moving traffic.
Abrasive action may be increased due to the presence of abrasion material like sand between the tires of vehicle and the aggregates exposed to the top surface. Thus, they should be hard enough to resist the wear due to abrasive action of traffic.
3) Toughness:
Aggregates in the pavement are also subjected to impact due to moving wheel loads.
The magnitude of impact increase with roughness of road and speed of vehicle
Severe impact is common when heavily loaded steel tired vehicles move on WBM. The resistance to impact or toughness is thus another desirable property of aggregates.
4) Durability
The aggregates used in roads are subjected to physical and chemical actions of rains and ground water, the impurities in them and that of atmosphere.
Thus it is desirable that the road stones used in the construction should be sound enough to withstand the weathering action.
The property of aggregates to withstand the adverse actions of weather may be called soundness.
5) Shape of Aggregates
Road aggregates may be rounded, angular, flaky or elongated.
Flaky and elongated particles have less strength than rounded and cubical particles. Thus, too flaky and too much elongated particles should be avoided.
6) Adhesion with Bitumen
The aggregates in bituminous pavements should have less affinity with water when compared with bitumen otherwise the bituminous coating on the aggregates will be stripped off in presence of water.
2. Bitumen
Bitumen refers to the viscous liquid or solid consisting essentially of hydrocarbons and their derivatives.
Bitumen is soluble in Carbon Disulphide C2S
Substantially non volatile
Softens when heated
Black or brown in color
Petroleum Bitumen: Obtained by refining process of petroleum
Natural Bitumen: Occurring as natural deposits
Straight Run Bitumen: Petroleum bitumen whose viscosity has not been adjusted by blending or by softening with cutbacks or other methods.
Blown Bitumen: Straight run bitumen further treated by blowing air through it while it is in hot condition
Composition of Bitumen:
Complex chemical mixture of molecules that are predominantly hydrocarbons
Carbon | 82-88% |
Hydrogen | 8-11% |
Sulphur | 0-6% |
Oxygen | 0-1.5% |
Nitrogen | 0-1%’
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1) Traces of metal:
Vanadium, Nickel, Iron, Calcium, Magnesium
Bitumen constituents are broadly classified as Asphaltenes, Resins and oils
2) Asphaltenes:
Dark brown friable solids
Have high polarity and interact or associate more actively
Mainly responsible for viscosity of bitumen
Higher Asphaltenes content result in harder, viscous bitumen with low penetration and high softening point
3) Resins:
Dark, Semi solid to solid
Fluid when heated and brittle when cold
Disperses the Asphaltenes throughout the oils to provide a homogenous liquid
Yields Asphaltenes on oxidation
4) Oils:
Colorless liquids
Yields Asphaltenes and resins on oxidation
Bitumen is considered to be a colloidal system consisting of Asphaltenes, resins and oils.
Key Takeaways:
- Elongation Index: - Elongation index of an aggregate is the percentage by weight of particles whose greatest dimension (length) is greater than one and four-fifth times (1.8 times or 9/5 times) their mean dimension. It is measured on particles passing through mesh size of 63mm and retained on mesh size of 6.3mm.
- Flakiness Index: - The flakiness index is defined as the percentage (by mass) of stones in an aggregate having an ALD of less than 0.6 times their average dimension.
- Higher Asphaltenes content result in harder, viscous bitumen with low penetration and high softening point
- The packages consist of the migration of reflective cracking in asphalt overlays, separation, stabilization of avenue bases, stabilization of avenue tender subgrades, and lateral drainage. ... For example, geosynthetics were in use because the Seventies to enhance the overall performance of unpaved roads on tender subgrade soils.
Key Takeaway:
- Aggregates form the major portion of the pavement structure, bear stresses occurring on the roads and have to resist wear due to abrasive action of traffic.
References:
1. Pavement Design: Yoder and Witzak Wiley
2 Traffic Engineering: L.R.Kadiyali Khanna Publishers
