Roadways in India India being second most populous nation of the world need many basic infrastructural growth in order to show a well all- round and sustainable growth. And roadways is one of the important infrastructural elements in the growth of any economy, it is not only used merely for the means of transport by common people but is used in a large volume to transport goods from one places to another having great economic presence. The road network in India is 2.3 Million km at present quantitatively. And road density in India is .66 km per square km of land,which is relatively good when compared with US (0.65),China (0.16) and Brazil(.20). The above para only talks about the quantity of road but in quality wise, India is far behind the best in the World.India has a mixed type of road with highly developed National Highways and on other side unpaved and narrow village roads. India has 4 km of road per 1000 of people which is relatively very small when compared to US with having 21 km per 1000 people and France with 15 km per 1000 of its people. But this is mainly so because India is very densely populated and so these figures may vary largely. Importance of Road connectivity in Villages and far-flung areas Roadways be it State Highways or National Highways or even less developed village roads plays important role in the socioeconomic development of any country. In India a large population still live in villages and many a times far away from towns or cities and in a rugged remote locations like in harsh Himalayan ranges or in deep dense forest. In order to bring to them the basic needs of growth and development to these people living in Villages they must be connected with roads so as to provide them with some basic amenities of Medical, Schooling etc which further will help them in their social development. Having connected with roads these village people living far away from towns and cities can easily transport their farm-produce to nearby processing units or markets for trading. Moreover their are many farm- products like fruits, vegetable etc which are perishable items and requires fast transport needs to nearby market so as to have good returns and to maintains their nutritional values and quality. With the connectivity of roads to far remote places and also to the villages large movement of people will start from villages to cities and towns which further will help in the development of these people. Now they can have easy access to medical facilities which might not be available in their local villages, they can now use Banks and other financial institutions to manage their funds which again will help them to strengthen their monetary growth. Will the connectivity of roads the students with Primary education from villages can have easy access to good professional universities and colleges for their higher studies. As discussed in the above two paragraphs development of roads in rural India as well as in places with rugged terrains and far-flung areas road plays a two dimensional role i.e. bringing growth to these areas in both socially as well as economically. This enhances the overall living conditions of the people belonging to these places. Importance of Road in economic development Roadways provide a major connectivity of goods from places of its production or produce to places of trade like markets in cities or with ports for their export. Roads provide door to door delivery of goods which is the most important feature of it and which cannot be possible with any other means of transport. Roads help in easy and fast delivery of goods from places to places especially the perishable items transport. The quantity as well as quality of roads of a country greatly contributes to economy and is a major indication of growth. And this is due to these reasons this needs to looked upon with extra care. Moreover roads play an important role in communication, linking people with people living in different areas physically separated from rugged and harsh terrain. Roadways as compared to waterways and air transport is very important as it reaches large geographical dimensions as compared to other. There are many means of transportation i.e. land, water and air transport. In Land transport roadways, Railways and Pipelines are major categories. There are many advantages and disadvantages of one over the other, but in this section we are talking about roadways so, listed below are some of the advantages which roadways have over other means of transport. Advantage of Roadways as a means of Transport Construction Cost is much lower Roads can traverse comparatively more dissected and undulating topography Roads can negotiate higher gradients of slopes and as such can traverse mountains such as Himalayas Radio transport is more economical in transportation of few people and relatively smaller amount of goods over short distances Provides door-to-door service, thus the cost of loading and unloading is much lower Used as a feeder to other means of transport, such as they rovide link between railway stations, air and sea ports
Transcript
Roadways in India
India being second most populous nation of the world need many basic infrastructural growth in order to show a well all-round and sustainable growth. And roadways is one of the important infrastructural elements in the growth of any economy, it is not only used merely for the means of transport by common people but is used in a large volume to transport goods from one places to another having great economic presence. The road network in India is 2.3 Million km at present quantitatively. And road density in India is .66 km per square km of land,which is relatively good when compared with US (0.65),China (0.16) and Brazil(.20).The above para only talks about the quantity of road but in quality wise, India is far behind the best in the World.India has a mixed type of road with highly developed National Highways and on other side unpaved and narrow village roads. India has 4 km of road per 1000 of people which is relatively very small when compared to US with having 21 km per 1000 people and France with 15 km per 1000 of its people. But this is mainly so because India is very densely populated and so these figures may vary largely.Importance of Road connectivity in Villages and far-flung areasRoadways be it State Highways or National Highways or even less developed village roads plays important role in the socioeconomic development of any country. In India a large population still live in villages and many a times far away from towns or cities and in a rugged remote locations like in harsh Himalayan ranges or in deep dense forest. In order to bring to them the basic needs of growth and development to these people living in Villages they must be connected with roads so as to provide them with some basic amenities of Medical, Schooling etc which further will help them in their social development. Having connected with roads these village people living far away from towns and cities can easily transport their farm-produce to nearby processing units or markets for trading. Moreover their are many farm-products like fruits, vegetable etc which are perishable items and requires fast transport needs to nearby market so as to have good returns and to maintains their nutritional values and quality.
With the connectivity of roads to far remote places and also to the villages large movement of people will start from villages
to cities and towns which further will help in the development of these people. Now they can have easy access to medical
facilities which might not be available in their local villages, they can now use Banks and other financial institutions to
manage their funds which again will help them to strengthen their monetary growth. Will the connectivity of roads the
students with Primary education from villages can have easy access to good professional universities and colleges for their
higher studies.
As discussed in the above two paragraphs development of roads in rural India as well as in places with rugged terrains and far-flung areas road plays a two dimensional role i.e. bringing growth to these areas in both socially as well as economically. This enhances the overall living conditions of the people belonging to these places.Importance of Road in economic developmentRoadways provide a major connectivity of goods from places of its production or produce to places of trade like markets in cities or with ports for their export. Roads provide door to door delivery of goods which is the most important feature of it and which cannot be possible with any other means of transport. Roads help in easy and fast delivery of goods from places to places especially the perishable items transport. The quantity as well as quality of roads of a country greatly contributes to economy and is a major indication of growth. And this is due to these reasons this needs to looked upon with extra care. Moreover roads play an important role in communication, linking people with people living in different areas physically separated from rugged and harsh terrain.Roadways as compared to waterways and air transport is very important as it reaches large geographical dimensions as compared to other. There are many means of transportation i.e. land, water and air transport. In Land transport roadways, Railways and Pipelines are major categories. There are many advantages and disadvantages of one over the other, but in this section we are talking about roadways so, listed below are some of the advantages which roadways have over other means of transport.Advantage of Roadways as a means of Transport
Construction Cost is much lower Roads can traverse comparatively more dissected and undulating topography Roads can negotiate higher gradients of slopes and as such can traverse mountains such as Himalayas Radio transport is more economical in transportation of few people and relatively smaller amount of goods over short distances Provides door-to-door service, thus the cost of loading and unloading is much lower Used as a feeder to other means of transport, such as they rovide link between railway stations, air and sea ports
Classification of Roads in IndiaIndia as compared to other nations of the world has the largest road network with
a total aggregating to about 33 Lakh Km. Depending upon the capacity of roads Indian roads can be classified mainly in the following six categories:
GOLDEN QUADRILATERAL SUPER HIGHWAYSNATIONAL HIGHWAYSSTATE HIGHWAYSDISTRICT ROADSOTHER ROADSBORDER ROADSDepending upon the type of material used for the construction of roads these are
classified into metallic and nonmetallic roads. The metallic roads are all-season roads and is of high quality in comparison to nonmetallic roads which mainly worn-out or tear-out very easily during rainy seasons.
Golden Quadrilateral Super HighwaysThese roads are built and maintained by the Central Government off India and
links the major cities like Delhi-Kolkata-Chennai-Mumbai-Delhi through six-lane Super Highways. These also includes the East-West corridor running from Silcher in Assam to Porbander in Gujarat and North-South corridor running from Srinagar in J&K to Kanyakumari in TN. The major objective of building these Super Highways is to shorten the road-link between big major cities of India having both social and economical perspectives. These Super Highways i.e. the Golden Quadrilateral, North-South Corridor and East-West corridor roads are built and maintained by NHAI under the Central Government of India.
National HighwaysThese National Highways are the second most important road network in India
linking the most extreme parts of the country. The prime objective of these National Highways is to bring in closer the extreme terrain and far flung areas in terms of geographical locations to bring about movement of people and goods. These National Highways are built and maintained by Central Public Works Department (CPWD). In order to give boost to the economic development of the country, the Government has embarked upon a massive National Highways Development Project (NHDP) in the country. The NHDP is the largest highway project ever taken in the country. The NHDP is being implemented by National Highways Authority of India. (NHAI)
State HighwaysState Highways are mainly built to link State Capital with the various District
Headquarters and is built and maintained by State Public Works Division (PWD) in States and UTs. These roads are very for the development of a particular state or UTs as it connects the District with State Capital moving goods and people to capital.
District Roads These Roads connects the District Headquarters with the other places within the
district. These roads are maintained by Zila Parishad.Other RoadsThese roads include those which are used mainly to connect the rural areas
and villages with towns or cities. These are very important and significant in Villages as this helps in socioeconomic development of the rural India. These helps in bringing the
basic necessities to and from from the villages to the towns or cities moreover it helps them to market their farm produce much more easily to the bigger markets located in nearby towns and cities. There are many Central or State run schemes which helps in development and maintenance of such roads and one such important scheme in the Pradhanmantri Grameen Sadak Yojna.
Border RoadsThese Border Roads are maintained and developed by Border Road
Organization(BRO) under the undertaking of the Central Government of India. The main aim of these border roads is to provide strategic support for both the armed forces and the people who are located along the vast and rugged borders of India. Indian borders are mostly located in the North and North-Eastern borders of India and mainly have very rugged climatic conditions ranging from extreme hot climatic conditions of Rajasthan to cold harsh climatic condition of Ladakh and dense forest and rugged terrains of North-eastern India. BRO, which is a Government of India undertaking established in 1960 has been given the responsibility to built and maintain these roads.
IRC classification of the Roads/highways in India
IRC(Indian Roads Congress) has classified the roads in the India in the following 5 categories:(a) National Highways(b) State Highways(c) Major District Roads(d) Other District Roads(e) Village Roads
National Highways(NH): National highways are the major arterial roads spanning in the length and breadth of the country and connects the Capital to the various state capitals of the country or with the neighboring countries. They also connect the famous tourism places of the country. National highways are numbered and written as NH-1, NH-2 etc. They have the highest design specifications.
Example : NH -1 Delhi-Ambala-Amritsar, NH-21 Chandigarh- Mandi- Manali.
State Highways(SH): State highways are the roads which connect the state capital to other states and to the district headquarters in the state. They have design
specifications similar to those of the National Highways because they carry enough traffic.
Major District Roads(MDR): These roads connect the district headquarters to the main town centers in the district, and to the headquarters of the other districts also. They also connect these major town centers to the other state highways of importance. They have lower design specifications as compared to the NH and SH.
Other district roads(ODR): These roads connect the rural areas town centers to the major district roads of higher importance.They provide the facilities for the transportation of the raw materials or the goods mainly of agricultural products from the rural towns to the higher markets and vice-versa.
Village Roads(VR): These roads connect the rural villages with one another and to the nearest higher level road or to the nearest town center. They have lower design specifications and many of them are not even metaled.
CLASSIFICATION OF ROADS IN INDIA:
As per the Nagpur Pl, the roads are classified asi) National highwaysii) State highwaysiii) District highwaysa) major district roadsb) minor district roadsiv) village roadsNECESSARY OF CLASSIFYING ROADS:- To plan a road network for efficient
and safe traffic operation , and for knowing the clear information of a particular root in a country, the classification of roads is necessary.
a. NATIONAL HIGHWAYS:- These are the important roads of the country. They connect state capitals, ports and foreign highways. They also include roads of military importance. They are financed by the central government.
b. STATE HIGHWAYS :- these are the important roads of a state. They connect important cities and district head quarters in the state , national highways & state highways of neighbouring states. They are financed by state government roads and buildings department of the state government constructs & maintain these roads.
c. DISTRICT ROADS :- these are the roads within a district . they are financed by zillaparishads with the help of grants given by state government.
d. THE MAJOR DISTRICT ROADS:- They are roads connecting district heade. quarters, taluk head quarters and other important town in the district production
andmarket centers with each other and with state & national highways & railways.f. OTHER DISTRICT ROADS :- They are district roads of less importanceg. VILLAGE ROADS:- they connect villages with each other and to the nearest
district road. They are financed by panchayats with the help of zillaparishads and state government.
A typical hill road (Ghaghas to Shimla- Himachal Pradesh) - in 2013
Ref: Highway Engineering - by S K Khanna & C E Justo
Functions of IRC, CRRI, and Roads wing of Surface TransportationHello there,
Roads wing of ministry of surface transport:The roads wing of the ministry of Surface Transport handles the road matters of the Central Govt. It is headed by a Director General. The Director General is assisted by two additional Director Generals(one for roads and one for bridges), a numbers of Chief Engineers, Superintending Engineers, Executive Engineers and Asst. Executive Engineers. The roads wing has a chief Engineer for the North-East region posted at Guwahati and a Liaison-cum-Inspectorate organization consisting of S.E’s and E.E’s in the various states. The functions of the roads wing of Surface Transport are:
(a) To control funds approved by Central Government for the development of National Highways.
(b) To control the central road fund.
(c) To prepare plans for development and maintenance of National Highways in consultation with state PWD’s.
(d) To oversee technically the quality of works executed by the agencies.
(e) To administer matters regarding road research.
(f) To examine technically the projects of roads and bridges prepared by the PWD’s.
(g) To administer the central road program other than National Highways in the Union Territories.
Highway Geometrics- (Camber, Land Width, Carriage way, Sight Distance, Super Elevation, Gradient)Hello, How you doing? Highway Geometric: This is the branch of the highway engineering which deals with the geometrical elements of the roads like, land of width, formation width, carriage way, side slopes, shoulders, kerbs, sigh distance, super elevation and highway curves. Land Width: It is total width of the land acquired by the Govt. along the road for the construction and maintenance of the roads. No other buildings by public can be constructed on the land width. Land width depends upon the following factors:
(a) It depends on the type of the road to be constructed, like NH require more width as compare to the lower level highways.(b) It depends on the anticipated future increase in the traffic on the route or the economic or industrial development of the areas which it aligns along its route. Carriage Way:
It is the width of the road which is used by the traffic for moving on it. It is generally central portion of the total land width and is paved and surfaced with the bituminous concrete for service to the road users. Width of the carriage way depends on the number of the lanes in the road which again depends on the class of the highway. If it is higher level road like NH then it will need more numbers of lanes and therefore the carriage way width will be more. Camber: Camber is the transverse slope provided to the road surface for the drainage of the rainwater for the better performance of the road. Camber can be written as 1 in n or x%.
Drainage of the rainwater is necessary(1) To maintain the safe value of the friction between the road surface and the tyres(2) To maintain the strength and durability of the surface concrete(3) To maintain the durability and strength of the sub-grade soil which can be harmed if the infiltration of the water takes place to it.There are generally three types of the cambers: (a) Straight Camber (b) Parabolic Camber (c) Mixed Camber.
Types of Camber
(a) Straight Camber: This type of camber is provided by meeting two straight surfaces at the crown. Crown is the central and top most point on the surface of the road. The edge shape produces in-convenience to the traffic so it is not used in general.
(b) Parabolic Camber: Parabolic camber is provided by providing a parabolic shape to the surface of the road. It is also not used in general because it has steep slopes towards the edges, which can create the outward thrust to the vehicles.
(c) Mixed Camber: Mixed camber is formed by use of the straight surfaces at the edges but parabolic surface at the centre. It is mostly used for the road construction because both the problem of the earlier two are solved if we use this camber.
Gradient: It is the slope provided to the surface of the road in the longitudinal direction for the vertical alignment of the road. There are three kinds of gradients:
Ruling gradient is the design gradient, so it is used to design the road in the vertical alignment. Limiting and exceptional gradients are provided in the limited stretch of the roads where necessary and in case of the emergencies or exceptional cases when such need arises respectively. Minimum gradient is the gradient which is required as the minimum from the drainage point of view in case of the plane areas.
Sight Distance: Sight distance at any instance is the distance along the center line of the road which is visible to the eye of a driver at an height of 1.2 m from the road surface such that an obstruction of height 0.15 m is visible to him. The heights of the eye of the driver and the obstruction is standardized by the Indian Roads Congress.
Sight Distance
Most important sight distance which are necessary to be studied here in the design point of view are:(a) Stopping Sight distance(b) Overtaking sight Distance1. Stopping sight distance(SSD): SSD is the sight distance which is necessary for a driver to stop a vehicle from the design speed to the 0 speed without any collision with the obstruction on the road. It is also known as the absolute minimum sight distance so this much sight distance is provided at all the cross section of the road. Over-Taking Sight Distance(OSD): OSD is the sight distance which is necessary for a vehicle running at the design speed to overtake a slower moving vehicle without collision with the vehicles coming from the opposite direction. Generally It is not possible to provide the OSD at every cross section of the road so, it is provided after a stretch of the road.
Super- Elevation: The outer edge of the road with respect to the inner edge of the road is raised in case of the horizontal curves, this is called super-elevation. Super-elevation is necessary to counter-act the centrifugal force due to the radius of the curve and speed of the vehicle.
Construction of WBM roads, WMM - Wet mix macadam - Transportation EngineeringHi, Here we are going to discuss the construction of the WBM and WMM roads in brief.
The water bound macadam road construction technique was given by the John Macadam. This technique in present day is used as given below.For WBM construction we use three materials:
1. Aggregates2. Screeners3. Binders.
Aggregates:We use the aggregates of different grades. IRC(Indian Roads Congress) has classified the coarse aggregates into 9 grades, according to their size.
For the construction of the WBM roads aggregates are used in the sub-base, base and surface course and so the aggregates are divided into 3 grades according to their size.Grade 1 - particles of size 90 mm to 40 mm.Grade 2 - particles of size 63 to 40 mm.Grade 3 - particles of size 50 to 20 mm.The grade 1 aggregates having size of 90 mm to 40 mm are preferred for the sub-base material and grade 2 for the base and grade 1 for the surface course. However, if we only use the WBM as the surface course, it gets deteriorated fast due to abrasion with the traffic so, bituminous surfacing over the WBM is general practice.
Screeners are the aggregates of the smaller sizes, generally 12.5 mm or 10 mm, for grade A and grade B. They are of the same chemical composition as of the coarse aggregates. For economic considerations IRC has suggested non plastic materials such as, crushed over burnt bricks, moorum, gravels, etc. provided the liquid limit of the material is less than 20%, plasticity index is less than 6.0% and the portion of fines passing 0.075 mm sieve is less than 10%. However if crush-able type of aggregates are used, use of the screeners may be disposed off.
Binders: Binders, are the layers of materials which are laid after the compaction of the aggregates and the screening materials one after the another. Kankar dust or lime stone dust may be utilized if locally available. The binding material with plasticity index value of 4% to 9% is used in surface course construction; the plasticity index of binding course material should be less than 6% in the case of the WBM layers used as base course or sub-base course, with bituminous surfacing. However if the screening used are of crushable material like moorum or soft gravel, there is no need to apply binding material, unless the plasticity index value is low. (II) - WMM(Wet mix macadam) road construction:Aggregates used are of the smaller sizes, varies between the 4.75 mm to 20 mm sizes and the binders(stone dust or quarry dust having PI(Plasticity Index) not less than 6%) are premixed in a batching plant or in a mixing machine. Then they are brought to the site for overlaying and compaction.
The PI(plasticity Index) of the binding material is kept low because it should be a sound and non plastic material. If the plasticity index is more then there are the chances of the swelling and more water retention properties. So this value should be kept in mind. Comparison of the WBM and WMM road construction:Although the cost of construction of the WMM is said to be more than that of the WBM sub-base and bases but the advantages given below will compensate for that. Here are the points of difference:
2. The WMM roads gets dry sooner and can be opened for traffic withing less time as compare to the WBM roads which take about one month for getting dry.3. WMM roads are soon ready to be black topped with the Bituminous layers.4. WMM roads are constructed at the faster rate.5. The consumption of the water is less in case of the WMM roads.6. Stone aggregates used in WBM is larger in size which varies from 90 mm to 20 mm depending upon the grade but in case of the WMM size varies from 4.75 mm to 20 mm.7. In case of WBM, stone aggregates, screenings and binders are laid one after another in layers while in WMM, aggregates and binders are pre-mixed in the batching plants and then brought to the site for overlaying and compacting.8. Materials used in the WBM are the stone aggregates, screenings and binder material(Stone dust with water) while in WMM material used are only stone aggregates and binders.9. Quantity of the WBM is generally measured in cubic meters while that of the WMM in square meters.
References: Highway Engineering by S.K. Khanna and C.E.G.Justo & Wiki answers.
Function of various pavement componentsHello There!
How you doing? Here is what you searched for but, after reading please leave a comment to improve the article.
Functions of various components of Pavement:
We know there are four pavement layers:1. Sub-grade2. Sub-base3. Base4. Surface course
Functions of each layer are described as below:
Sub-Grade :
The load is transferred by the sub-grade effectively to the earth mass. However the locally available earth is used to construct the sub-grade but it becomes necessary that the sub-grade should be of required strength.
This makes it necessary to check the strength characteristics of the sub-grade by using the various methods. Here is the list of the tests that are employed to check the strength of the sub-grade:(a) California bearing ratio test.(b) California resistance value test.(c) Tri-axial shear test.(d) Plate load test.California bearing ratio test is a kind of penetration test, in which we get the value of the California bearing ratio of the given soil sample. The test can also be performed in the field to take the in-situ measurements.
The value is used to design the thickness of the flexible pavements by using some empirical charts.This test is also used to calculate CBR value for the other layers too. California resistance value is got by using the Hveem stabilometer. This test is used in empirical methods of the flexible design methods, based on the soil strength.
Tri-axial shear test: This test gives the value of the shear strength of the soil, but it is not done, because the values obtained from this test are used only in a very few theoritical methods of flexible pavement design.
Plate Load Test : In this test we make use of the plates of some larger diameter. In this test we get the values of the elastic modulus of sub-grade. These values are used in the methods of flexible pavement designs like that in Mcleaod method and in method of layer system approach for analysis by Burmister.
The modulus of sub-grade reaction is also calculated for the rigid pavement analysis by the Westergaard's approach.
Sub-base and base course:
Base course and sub-base course is used in the flexible pavement to disperse the upcoming loads to large area through a finite thickness, so as to increase the load bearing capacity of the pavement. The material used are the broken stones, or gravels, or bound or unbound aggregates. Sometimes the bricks can also be used as the sub-base and base materials. Generally the sub-base layers have the inferior quality of aggregates, than that used in the base course. Generally smaller aggregates are used because the larger gravels or aggregates have the tendency to sink to the lose sub-grade soil under the heavy loading.
The function of the sub-base or the base layer in case of the rigid pavement is to :
1. Check the pumping action.
2. Protecting the sub-surface against the frost action.
The basic purpose of the sub-base and base layer is to transfer the load through a dispersed/larger area to the sub-grade. So it must of sufficient strength to do its job.
These layers are evaluated using a suitable strength or stability tests like the plate load test, california bearing ratio test, and the Hveem stabilometer test, where each test has its own significance and importance.
Wearing course:
The top most layer serves as the smooth riding surface for the traffic, and it wears all the abrading forces. The top most layer is constructed with the superior quality of aggregates because it has to wear the maximum intensity of loads.
It has to be water proof to stop the water penetration to the lower layers, so in case of flexible pavements the bituminous concrete is used and it is well compacted, and in rigid pavements the cement concrete is used and is well compacted so that no water penetration takes place.
There is no direct test to check the stability of the surface course but the bituminous concrete used in the flexible pavement is checked for its suitability. Marshall stability test is used to determine the optimum content of the bitumen to be used in the aggregate mix, based on the stability density, VMA and VFB of the given grading of the aggregate mixture.
Expansion and contraction joints in Rigid Pavements.Hello There,How you doing? Here is what you searched for but, after reading please leave a comment to improve the article.
I have studied about the expansion and contraction joints. In the rigid pavements, like the cement concrete pavements, the cement slab is laid on the sub-grade. The concrete changes its volume with the change in the temperature.
If the natural temperature of the concrete is low i.e. concrete is laid down in the season of winter, then the chances are there that concrete will undergo expansion in the summer season.
Expansion joint
Similarly, if the concrete is laid in the summer season then natural temperature of the concrete is already high, so the concrete will contract in the season of the winter.
Whether the concrete is going to expand or shrink, one has to provide the expansion or the contraction joints respectively.
Spacing of the expansion joints: The spacing of the expansion joint can be determined as below: (expansion) e = co-efficient of thermal expansion * Ls * (t2-t1)
we provide width of the joints double then 'e', 50% allowance is provided for the filler material.
Spacing of the contraction joints: The contraction of the concrete is opposed by the frictional force between the sub-grade and the concrete.
This frictional force should always be less than the ultimate strength of the concrete
which resists the tensile forces developed in it due the contraction force and the frictional force.
Contraction joints on rigid pavements
Frictional force is dependent on the surface area of the concrete(L*B), and the resisting force depends upon the (h*B) of the concrete, so we can get the minimum spacing required if we equate the two forces.
Reference: Highway Engineering by S.K.Khanna and C E Justohttp://transportationengineering2012onwards.blogspot.in/2013/03/expansion-and-contraction-joints-in.html
