Category Archives: TRANSPORTATION ENGINEERING

Bitumen for roads – Bitumen Uses, Grades and Types

Bitumen for roads is an important topic to understand when it comes to road construction. Bitumen is used in road construction because of the wide range of features and advantages it possesses over other pavement construction materials. The significance of bitumen in the construction of roads will be demonstrated in this article. In addition, we shall see bitumen road layers, various bituminous materials, cutback bitumen, bitumen grade, and bitumen properties.

  1. Bitumen for roads – Bituminous binder types
    1. Bitumen vs Tar – Comparison
    2. Tar manufacturing
  2. Desirable properties of bitumen- an important topic in bitumen for roads
  3. Bitumen for roads – Types of Bituminous materials
    1. Cutback bitumen
    2. Bituminous emulsion
  4. Grade of bitumen for roads – Types and Uses
  5. Bitumen road layers

Bitumen for roads – Bituminous binder types

There are two types of bituminous binder for road construction.

  • Bitumen (by distillation of crude oil)
  • Tar (Produced from coal)

So, what are the difference between them?

Bitumen vs Tar – Comparison

The table below shows a comparison between tar and bitumen.

BitumenTar
Petrolium productDistillation of coal or wood
Soluble in carbon disulphide and carbon tetrachlorideSoluble in toluene only
Temperature succeptibility is lowTemperature succeptibility is higher than bitumen
Free carbon content is lessFree carbon content is more
Comparison between tar and bitumen

Now, let’s sneak into the manufacturing of tar, being one of the important bituminous materials

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Tar manufacturing

Bitumen for roads - Construction in progress
Bitumen for roads – Construction in progress

Generally, tar is made by heating coal inside a chemical apparatus. Most tar is produced from coal as a byproduct of coke production, but it can also be produced from petroleum, peat or wood.

The major steps in tar manufacturing are,

  • Coal undergoes carbonation and produces crude tar
  • Crude tar undergoes distillation/ refining and produces a residue
  • The residue blends with distilled oil fraction and produces tar

I am going to tell more about the properties of bitumen now.

Also read: Classification of roads-5 types of roads full details

Desirable properties of bitumen- an important topic in bitumen for roads

Bitumen for roads - Properties
Bitumen for roads – Properties

The desirable properties of bitumen are,

  1. Viscosity of bitumen during mixing and compaction is adequate
  2. Bituminous material should not highly temperature and susceptible
  3. In presence of water the bitumen should not strip off from aggregate
  4. The adhesive property of bitumen binds together all the components without bringing about any positive or negative changes in their properties
  5. Bitumen is insoluble in water and can serve as an effective sealant
  6. Due to versatility property of Bitumen it is relatively easy to use it in many applications because of its thermoplastic property
  7. Bitumen play a vital role in distributing the traffic loads on the pavement to the layers beneath

Bitumen for roads – Types of Bituminous materials

Okay. So, what are the types of bituminous materials that are used in flexible pavement construction? Below is the list for you.

  1. Paving grade material
  2. Modified bituminous binder
  3. Cutback bitumen
  4. Bitumen emulsion

Among the list, cutback bitumen is the major. Let me tell you more details about cutback bitumen.

Cutback bitumen

Cutback bitumen is the bitumen the viscosity of which is reduced by a volatile diluent. It is used in low-temperature mixing.

Three types of cutback bitumen are available

  1. Rapid curing
  2. Medium curing
  3. Slow curing

The diluent while mixing varies with the type of cutback bitumen.

Type of cutback bitumenDiluent
Rapid curingNafthal, gasoline
Medium curingCarosine or diesel oil
Slow curingHigh boiling point gas oil
Type of cutback bitumen and suitable diluent

Bituminous emulsion

bitumen emulsion
Bitumen emulsion

A bitumen emulsion is a liquid product in which a substantial amount of bitumen suspended in a  finely divided condition in an aqueous medium and stabilized by means of one or more suitable material

Three types of bitumen emulsions are available

  1. Rapid setting
  2. Medium setting
  3. Slow setting

Also read: Alignment of road: Factors affecting- obligatory points with figures

Grade of bitumen for roads – Types and Uses

To determine the grade of bitumen, penetration test is conducted. The results are expressed in 1/10 mm. When penetration value is represented as 80/1000, it is called grading of bitumen.

The old method of grading is viscosity test. Two viscosities kinematic and absolute and penetration value by penetration test results are collected. Based on this, bitumen is graded. The tables shows the grade of bitumen and values of viscosity in accordance with penetration.

Grade of bitumenAbsolute viscosityKinematic viscosityPenetration
VG 1080025080- 100
VG 20100030060- 80
VG 30240035050- 70
VG 40320040040- 60
Grade of bitumen and viscosity

Let me tell you the application of each of the grade of bitumen now.

VG- 10- Used in spray application since viscosity is very less

VG- 20- Used in cold area

VG- 30- Commonly used in India

VG- 40- High grade bitumen used in high traffic areas

Okay. So, lets’ learn about the bituminous layers.

Bitumen road layers

Let’s first look into the road layers to understand bitumen road layers.

 bitumen road layers
bitumen road layers

The bitumen road layers come in the surface layer shown in the figure above. The figure below shows that. Bituminous mix consists of aggregate and binder. Aggregate consists of coarse aggregate, fine aggregate and filler less than 0.075mm.

Bitumen road layers
Bitumen road layers
  • Bituminous concrete consists of aggregate and bitumen.
  • Thickness of base course depends on grading of aggregate
  • Dense graded aggregates are provided in base course. That is the permeability will be very less
  • Number of voids should be very less
  • Dense bituminous macadam should be given as a binder course

So, the trip is over. Hope the time you spend for reading about the bitumen for road was worth it.

MUST READ: Road margins- 6 types of road margin in highway

Happy learning!

Intelligent transportation system – Components of Intelligent transportation system

Intelligent transportation system is a hot topic among all civil engineering subjects that has gained popularity and many countries are successfully implementing it. With the rapidly exploding population, ITS has even become a mandatory technique in all countries. Here, we are going to read through the main components of the intelligent transportation system. We will swim through the benefits of intelligent transportation system in the middle, then to uses and challenges of ITS.

  1. What is intelligent transportation system?
  2. Components of intelligent transportation system
  3. Benefits of intelligent transportation system
  4. Uses and challenges of intelligent transportation system
    1. 1. Use of cameras equipped with automatic number plate recognition(ANPR)
      1. Advantages
      2. Challenges
    2. 2. Speed violation recording cameras
      1.  Advantage
      2. Challenges
    3. 3. Cameras for recording violations of passing through red-lights at intersections
      1. Advantages
      2. Challenges
    4. 4. Equipping the transportation system with GPS
      1. Advantages
      2. Challenges
    5. 5. Use of intelligent routing systems for public transportation passengers
      1. Advantages
    6. 6.  Modern informative systems for offenders
      1. Advantages
      2. Challenges

What is intelligent transportation system?

What is Intelligent Transport System is the first step to dive in the topic. They are advanced applications which, aim to provide innovative services relating to different modes of transport and traffic management and enable various users to be better informed and make safer, more coordinated, and ‘smarter’ use of transport networks. In ITS the information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management, as well as for interfaces with other modes of transport.

Another answer to the question of what is Intelligent transportation system (ITS) is that, it is the application of sensing, analysis, control and communications technologies to ground transportation in order to improve safety, mobility and efficiency. ITS includes a wide range of applications that process and share information to ease congestion, improve traffic management, minimize environmental impact and increase the benefits of transportation to commercial users and the public in general.

Now, let me walk you through the main components of intelligent transportation system.

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Components of intelligent transportation system

Components of intelligent transportation systems

The main components of intelligent transportation system are,

1. Accurate tracking system
GPS enabled vehicles along with smartphone apps will help citizens to track buses and other vehicles.

2. Electronic timetables
Schedules of bus service should be updated in standard format which can be easily read by people and utilised by softwares.

3. Smart model to predict time of arrival
Transportation studies like that be conducted in IIT Madras, funded by Ministry of Urban Development. should be encouraged to obtain a robust algorithm to predict the arrival time of buses, which is what a citizen needs.

4. Standardisation by regulating authority

This is very important among all the components of intelligent transportation system. An authority should be set up which can standardise various components of the public transport and encourage the use of better and smart IT services in transport sector

5.Smart commuting

Latest information on traffic jams, accidents and ways for navigation

6. Mobile technology

App based technology, incentives for young technical entrepreneurs

7. Smart traffic control

Dynamic controls of traffic signals instead of current static control, automated system.

8. Scalability

The ITS should be easily applicable to 2nd tier cities so that problem of congestion doesn’t arise in the first place

9. Improved and better BRT system enacted with public participation

10. Installing CCTVs on traffic routes and in buses.

11. Creation of flyover and overbridges to eliminate need of traffic lights

12. Electronic payment of fare

13 Traveller’s advisory system like the use of advisory radio, SMS services, internet etc

14. Highway Management Systems: Use ramp metering techniques to measure and regulate by knowing the traffic entering or leaving the highway

15. Emergency Management Systems: To manage any unforeseen emergencies

16. Railroad Crossing: Gives signals about approaching rail junctions

17 Wireless communication System

18. Safe driving Support System

This includes,

a) Right turn collision prevention system

b) vehicle detection system
c) Pedestrian detection system

d) voice guidance

e) display warning

18. Electronic toll payment System

19. Computational technologie

20. Inductive loop detection and sensing technology

21.Freeway management.

Cool! Now how are these components of the intelligent transportation system benefiting transportation? Let’s see below.

Benefits of intelligent transportation system

traffic at night - Components of intelligent transportation systems

The main benefits of intelligent transportation are as follows.

  • Develop (and subsequently renew), a secure and effective revenue collection system – this has formed the backbone of the ITS
  • Develop enhanced operations management capabilities to provide reliable services and deal with disruptions
  • Provide communications for staff security
  • Provide improved passenger information
  • Obtain data for planning, resource optimisation and performance monitoring
  • To assist the achievement of the quantity and quality of the service required in the service contract with the province of Florence

• To generate the trip logs, analysis and reporting required by the province of Florence under the service contract

• To manage the daily operations, on both normal and disrupted state

• To manage the driver vehicle handovers and shift-changes

• To provide the platform for real-time and other information to passengers

• To provide the platform for e-ticketing

• To identify vehicle faults and assist rapid response

• To support demand responsive transport and other non-standard mobility services

• To generate and manage data for post-event analysis, including running time analysis, scheduling, resource optimization, and incident investigation

So, I walked you through the important benefits of intelligent transportation system.

Its time to see the results now.

Uses and challenges of intelligent transportation system

Components of intelligent transportation systems

1. Use of cameras equipped with automatic number plate recognition(ANPR)

Equip the intersections with traffic light crossing violations recording system and video surveillance cameras monitoring traffic flow

Advantages

Cameras are capable of fining any number of offending vehicles simultaneously

Challenges

  • Drivers cover the number plate of their cars daily in order to not to be fined
  • Some drivers who repeatedly pass specific passages try to destroy or damage the cameras and their equipment.

2. Speed violation recording cameras

Fixed cameras equipped with radar technology are assembled to identify and record speed violations

 Advantage

Assured of getting fined through being caught on camera, drivers rarely attempt to drive over the speed limit

Challenges

  • After identifying the locations where the cameras are installed, drivers may attempt to increase their speed in the distances between cameras, and this may cause many disturbances in traffic flow.
  • Due to the weakness of technology, identifying motorcycles is not possible in this system

3. Cameras for recording violations of passing through red-lights at intersections

Cameras are assembled at intersections  to record the red light running violations.

Advantages

A decrease in this kind of violation will have a direct effect in reducing car crashes and capital loss.

Challenges

  • In many intersections, due to the low quality of crosswalks and zebra crossings, it is really hard to determine a threshold running from which enables the driver to be known as an offender
  • As in many intersections, turning left or right is not legally forbidden, it is really a hard job to distinguish the vehicles doing so from the violators.

4. Equipping the transportation system with GPS

Position of the buses and the approximate arrival time of buses to stations can be calculated those who are speeding or using unauthorized routes can be identified

Advantages

  • Reduction of dangerous high speed of buses
  • Decreasing of delay time of journey

Challenges

  • Some drivers try to deactivate the GPS before attempting violation. They cover the GPS with aluminum foil to make it disconnected from the center.
  • Due to the need for a GPRS platform for sending the information to the center, using this system in Tehran is very expensive.
  • Due to the low average educational level of drivers and users of public transportation services, the relevant systematic training for using this system will be needed.

5. Use of intelligent routing systems for public transportation passengers

Passenger can receive information about the journey duration and the best manner of navigation after determining the origin and destination and also specifying the desired transportation mode such as metro, taxi, bus or walking

Advantages

 Decrease in delay of journeys and an increase in productivity.

6.  Modern informative systems for offenders

All fine notifications and notices for a technical test will be informed to the offenders via SMS

Advantages

  • Deliver the fine notifications to the offenders, omitting the process of printing and stuffing envelopes with fine notification
  •  Informing all offenders of their violations in an online manner, and creating a cohesive database of the offenders.

Challenges

  • As the telecommunications system and necessary infrastructure have not been completely developed, some problems in sending the SMS to offenders have been occasionally observed.
  •  Informative limitations such as length of words in SMS.

That’s it about ITS.

Continue learning!

MUST READ: Basic of civil engineering; Simple and in-depth guide

Bitumen Softening Point Test – Ring and ball method

The bitumen softening Point Test is done to determine the consistency of bitumen. Bitumen is a viscoelastic material, which means it behaves like both a liquid and a solid state. It does not have a specific melting point. As the temperature increases, the bitumen becomes softer and the viscosity of the bitumen decreases. One of the common parameters for classifying bitumen is the softening point of the bitumen. This property shows at what temperature the bitumen softens. 

Bitumen Softening Point Test

Bitumen softening point is measured in different ways such as:

  • Ring and Ball Method (R&B)
  • Krämer-Sarnow Method (KS)
  • Mettler Softening Point Method
  • Capillary Method
  • Flow Point Method
  • Drop Point Method

The ring and Ball method is the most frequently used to determine the softening point of bitumen.

Bitumen roads
Bitumen roads

Why Is The Bitumen Softening Point Important?

To pave the roads and aeroplane runways, it is necessary to use a type of bitumen that has a specific degree of softness. Choosing a suitable bitumen with a good softening point depends on the weather condition and traffic loads.

For example, if the average temperature in a region is high during a year, bitumen with a    higher softening point should be used to make asphalt pavement. If during the year, the number of vehicles crossing this road is high and they put a  lot of pressure on the road surface, more bitumen should be used in the asphalt. This work increases the strength of the asphalt.

Related posts – Bitumen

International Standard Methods of softening point test

The softening point  test  of  bitumen  is  in  the  accordance   with  the following standards:

  • ASTM D36
  • ASTM E28-67/E28-99
  • ASTM D6493 – 11
  • IS 1205
  • EN 1427
  • IP 58
  • ISO 4625
  • JIS K 6863

The most common standard method for determining the softening point of bitumen is ASTM D36, which we will discuss further. You can see the steps of the Ring and ball method through the Video produced by the Infinity Galaxy team.

Softening point test of bitumen – Ring and ball method (Video)

YouTube video
Youtube video

Softening Point Test Procedure

The ring and ball method is widely used to determine the softening point of bitumen. In  the  infographic  below, you  can  see  a  summary  of  the  bitumen softening point test:

Softening point test procedure
Softening point test procedure

The required equipment to do the bitumen softening point test are:

  • Two steel balls
  • Two brass rings
  • Beaker
  • Thermometer
  • Heater
  • Knife
  • A glass surface 
  • Bitumen
  • The bases holding the rings

Bitumen Softening Point Test Steps:

  • In the first step, it is necessary to prepare the test sample. Heat the bitumen to a   temperature between  75  and 100 °C. Stir the bitumen well until it becomes completely liquid and free of air and water bubbles. Heat the rings to the approximate temperature of the bitumen. Prepare a mixture of glycerin and dextrin in equal proportions.
  • Cover the surface of the metal or glass plate with it. Pour the heated bitumen into the rings to fill them. After cooling in the air, it is necessary to draw the extra bitumen with a heated knife at an angle of 45 degrees on the surface of the rings. So far you have understood how to prepare the sample.  In the following, we will explain the process of conducting this test.
  • Place the rings filled with bitumen on the bases and place them in a water bath with a temperature of 5 °C for 15 minutes. Cool the steel balls to a temperature of 5 °C. Put them in the beaker and fill them with distilled water up to about 50 mm above the rings. Now place the steel ball in the centre of the ring and tangent to the bitumen and heat it until the temperature rises 5±0.5 °C/min.

Ring and ball method – Results

  • As the temperature increases, the bituminous material softens and the balls sink through the rings. Continue heating until the balls on the bitumen reach the surface of the metal blade under the rings and note the temperature when each of the balls contacts the bottom of the plate. Consider the average of the two temperatures obtained as the bitumen softening point.
  • An important point in this experiment is the process of heating the beaker and its contents, i.e. bitumen.   Since this test is very sensitive to heat, it is necessary to use the same heating rate throughout the test. It should be noted that if the bitumen is blown and hard, glycerin liquid is used instead of water.

Penetration Test for Bitumen – Significance and Procedure

The penetration test for bitumen is a laboratory method for grading bitumen based on its hardness. In this test, the amount of penetrating a specific needle into the bitumen is measured.

More than 85% of bitumen is used in road construction. Weather condition affects on bitumen binder. In cold weather, bitumen becomes hard, and the possibility of cracking increases. On the other hand, hot weather causes bitumen becomes soft and sticky.

Both situations are not acceptable as a result of civil engineers using penetration tests.

What is the Penetration Test of Bitumen?

The penetration test for bitumen is a laboratory method for grading bitumen based on its hardness. In this test, the amount of penetrating a specific needle into the bitumen is measured.

This value is reported in a tenth of a millimetre or Deci-millimeter (DMM) as a penetration value. The penetration test can be used for refinery bitumen, emulsion bitumen, and oxidized bitumen. Based on this test bitumen is classified into penetration grades of 20/30, 30/40, 40/50, 50/60, 60/70, and 80/100.

This test can measure the penetration value in the range of 20 to 300 dcmm. It can recognize the bitumen consistency and stability of bitumen.

Let’s see this test history and application.

The Bitumen Penetration Test History

The first uses of the penetration test, date back to the early 19th century. Before that, the hardness of bitumen is measured based on the Chewing test. It was a completely experienced test. Through that, an engineer chews a moderate-temperature bitumen sample. Then reports the hardness of bitumen according to the difficulty of chewing. Because of the chewing test’s inaccuracy, the penetration test was introduced to the industry. 

An overview of the Bitumen Penetration test Importance

More than 85% of bitumen is used in road construction. Weather condition affects on bitumen binder. In cold weather, bitumen becomes hard, and the possibility of cracking increases. On the other hand, hot weather causes bitumen becomes soft and sticky. Both situations are not acceptable as a result of civil engineers using penetration tests.

Bitumen with high penetration values is suitable for cold weather. Because it does not harden and crack when exposed to low temperatures. On other hand, bitumen with smaller penetration values is suitable for hot weather. Because high temperatures can not soften it. Most workable penetration bitumens are penetration grades 60/70 and 80/100. Penetration grade 60/70 can apply to road construction in warm weather and 80/100 is suitable for cold weather.

Bitumen penetration grade 80/100 means that the needle penetrates into the bitumen in the range of 80 to 100 decimeters.

How Is the Penetration Test of Bitumen Performed?

In the following, you can familiarise yourself with the apparatus and the procedure of the test based on ASTM D5. Before that watch the below video by Infinity Galaxy which introduces the penetration test of bitumen.

r

 Apparatus

  • Penetrometer 
  • Container
  • Water bath
  • Stopwatch
  • Thermometer
penetrometer

Procedure 

In the first step, bitumen should be heated up until it becomes liquid. Bitumen should not be heated in a temperature range above 90-100 degrees Celsius otherwise it will burn. While the temperature rises, stir the bitumen to make sure it is uniform. Bitumen should also be free of water and air bubbles.

In the next step, pour the melted bitumen into the container and let it cool at room temperature. 

After that put the bitumen container in the water bath with a constant temperature of 25 degrees Celsius and let the sample reach the same temperature.

Then place the container under the penetrometer. Move down the needle just above the bitumen surface. 

Thereafter, apply the needle which has a 100gr load just for 5 seconds. Repeat the test 3 times and write down the results each time. The needle tip in each repetition should be apart 10mm from the previous measurements.

Report the mean value as the penetration value of the bitumen sample. The following picture is other important bitumen tests in road construction:

Infographics – 10 Major bitumen tests

Types of Bridges – Top 7 Bridge Design Types and Principles

Types of Bridges in civil engineering can range from modest constructions to massive, eye-catching pieces of art – and everything in between. A bridge serves its sole purpose as long as it transports us across a gap. The required passage may be for a road, train, pedestrians, canal, or pipeline. A river, a road, a railway, or a valley may be crossed. Types of bridges are an important classification in civil engineering. In today’s blog, we are going to learn about different types of bridges in detail.

Types of bridges and Bridges design types in civil Engineering

The types of bridges are broadly classified as follows on the basis of form and type of superstructure

  • Arch Bridge
  • Beam bridge
  • Cantilever bridge
  • Suspension bridge
  • Cable-Stayed Bridge
  • Tied-Arch Bridge
  • Truss Bridge

Let’s dig deeper into each of the types now.

Arch Bridge – Types of Bridges

Arch Bridge
Arch Bridge
  • A dead load of a bridge is the weight of the bridge itself, plus the weight of whatever it is carrying (the live load). The forces of load and gravity, which would otherwise send a bridge sliding downhill, are used to hold an arch bridge aloft instead. 
  • An arch bridge works by channelling gravity’s downward force into the structure’s centre — toward a central stone known as the keystone — rather than straight down.
  • Compression is the principle that allows the arch below to support the surface, or deck, above it.
  • Temperature changes can destabilise fixed arch bridges, hence the arch design is occasionally changed with hinges at each base and even the span’s centre.
  • This allows longer arch bridges to adjust to material expansion and contraction when temperatures fluctuate.

Also read: Bridge components explained – Types and functions.

Beam Bridge – Types of bridges

The beam bridge was the first form of bridge ever created due to its simplicity. It is still the most cost-effective to construct. All you need is a crossbeam that spans the gap and is supported at each end by an abutment. A girder bridge is a form of beam bridge that uses steel girders for reinforcement. 

beam bridge
beam bridge
  • Gravity presents a greater issue when creating a bridge since, unlike a building, the majority of the space beneath it is empty.
  • To resist gravity and bear the full load, a beam bridge might be supported merely by two abutments, one at each end.
  • But there’s a catch with beam bridges: the longer a bridge is and the more people, cars, and other objects it carries, the heavier the entire weight becomes.
  • The more abutments on a beam bridge are spaced apart, the less stable the structure becomes. 
  • You may make a long, stable bridge by putting supports in the middle, known as piers or stanchions, and connecting sections between them.
  • The Yolo Causeway in Sacramento, California, is 3.2 miles long, and the Lake Pontchartrain Causeway in Louisiana is 24 miles long.
  • The force of compression drives the weight inward onto piers in the middle of the bridge in beam bridges.
  • Simultaneously, the tension pulling or stretching force pulls the load outward toward the bridge’s abutments on both ends.

Also read: Highway Engineering- Definition, Importance and Construction Details

Cantilever Bridges Types

Cantilever construction is used on some bridges.

  • This design uses a vertically anchored pillar to support a horizontal deck that extends out from one or both sides across the span.
  • Both the above and below are frequently used to support the load.
  • A good example of cantilever construction is a diving board or platform.
cantilever bridge
cantilever bridge

Suspension Bridge Types

Suspension bridges are exactly what they sound like: they’re supported by vertical pillars or pylons that are linked by suspension cables.

Suspension bridge
Suspension bridge
  • Smaller, vertical suspenders are attached to these main cables and use tension to hold the bridge deck up.
  • Tension is the main force that sustains these types of bridges.
  • Despite the fact that the original suspension bridges were composed of simple ropes supporting wooden planks, the suspension technique now allows for vast spans across wide canals.
  • However, because these bridges are only attached to the ground in a few locations, they might shake when heavy traffic passes beneath them.
  • Vibrations can be caused by wind or movement across a bridge.
  • When these reach a specific frequency, resonance occurs, which is the same mechanism that causes the glass to shatter when a trained vocalist hits a high enough note.
  • Bridge crossings can be disrupted and collapsed if vibrations are strong enough. 
  • Torsion, a twisting force commonly generated by external variables such as wind, can also impact these bridges, causing unsafe movement.
  • Travelers can be thrown off a bridge if the surface twists significantly while they are on it.
  • While torsion causes tension in a vertical plane, shear causes stress in a horizontal plane.
  • It occurs when opposing environmental pressures act on a single, fixed component of a bridge, causing it to break like a stick between two hands.

Also read: Cofferdams – Types & Construction methods

Cable-Stayed Bridge

  • A suspension bridge with a cable-stayed bridge connects the crossbeam or bridge deck directly to pillars or towers.
  • There is no main cable, only a slew of vertical suspenders attached to the tower’s summit.
  • Tension is used by these suspenders to keep the bridge deck solid and in place.
Cable Stayed Bridge
Cable Stayed Bridge

Tied-Arch Bridge

  • The qualities of an arch bridge and a suspension bridge are combined in a tied-arch bridge.
  • It supports an arched structure with horizontal force from both sides, similar to a normal arch bridge.
  • Instead of supporting the building from below, the arch rises over the road, with vertical ties descending to provide additional decking support. 
  • Because they resemble a bow from the side, these are sometimes known as bowstring bridges.
  • This bow supports the weight and keeps the bridge stable by combining the tension of its vertical cables with the compression of the arch.
Tied arch bridge
Tied arch bridge

Also read: Golden Gate Bridge: Design and 2 Main Issues

Truss Bridge

  • The load on a truss bridge is distributed across a succession of tiny sections that are joined together.
  • Bridge trusses are typically formed by structural beams for smaller bridges or box girders for bigger bridges, and are joined in a sequence of triangles by welded or riveted joints. 
  • The bridge is held up by tension from vertical steel or timber supports, while compression from diagonal truss supports adds stability by directing the weight toward the centre, similar to an arch.
Truss bridge
Truss bridge

That’s it about the main types of bridges. Each of these has advantages and disadvantages. We need to decide on the type of bridge based on the requirements.

Let me know in the comments if you need any further information.

Happy learning!

Highway Engineering- Definition, Importance and Construction Details

Highway engineering is an important topic in civil engineering. It includes the study of roads in depth. The technical aspects involved in this subject plays a significant role in construction of different types of roads. In this blog, I will show you all the details of the subject including the definition, topics, importance etc.

Let’s start from scratch.

What is Highway Engineering

Highway engineering is a subset of highway engineering that deals with the planning, development, and upkeep of various types of roads, tunnels and bridges. It plays an important role in ensuring safe and efficient transport of people and goods. It entails researching the following topics:

1) Highway planning, location, and growth.

2) The materials needed to build a highway.

3) The performance of highway traffic and its regulation.

4) Road drainage, etc.

Before we jump on to the details, let me tell you the importance of highway engineering.

Importance of Highway Engineering

Highways top view
Highways top view

The Importance of roads is summarised below.

1. They provide transportation for people, commodities, raw materials, and other items to various parts of the world.

2. In hilly areas, they are the only means of contact.

4. Assists in the upkeep of law and order in a government.

Let’s talk a bit about the planning of highways in the next section.

Planning and Development of Highway Engineering

The prediction of existing and potential traffic volumes on a road network is part of highway planning.

Highway planning is also a fundamental requirement for highway construction. Highway engineers work hard to anticipate and assess all potential civil consequences of highway systems.

The negative effects on the environment, such as noise pollution, air pollution, water pollution, and other ecological impacts, are among the factors to consider.

What are Highway plans?

In highway engineering, Highway plans or Highway drawings are drawings created from data obtained during various surveys conducted for the purpose of locating a highway.

The main map, index map, preliminary survey plans, and other plans or sketches prepared in connection with a road project are examples. On separate papers, the specifics of additional works such as bridges, culverts, railway crossings, and so on are planned.

Purposes and Objectives of Highway Plan

1) To discover how the highway works.

2) To estimate the cost of the road project.

Its time to know about the construction.

Construction of highways

Newly constructed highways
Newly constructed highways

In most cases, extensive surveys and subgrade planning precede highway construction. There are many aspects of highway design that can be broken down into technological and commercial components.

The following are some examples of each:

Elements of technology

  • Material quality
  • Installation techniques
  • Traffic

Commercial elements 

  • Environmental considerations in contracts
  • Aspects of politics and law
  • Concerns from the public

Regardless of the project type, highway construction usually starts at the lowest elevation of the site and progresses upward. By looking over the project’s geotechnical requirements, we get an idea about the following:

  • Current ground condition.
  • Specific equipment requirement for excavation, grading, and material transportation to and from the site.
  • Properties of material to be excavated.
  • For below-grade work, dewatering requirement.
  • Excavation safety criteria
  • Quantities of water for dust control and compaction

How about the maintenance of highways? I will show you in the next section.

Maintenance of highways

The ultimate goal of highway maintenance is to correct flaws and maintain the structure and usability of the pavement. In order to construct an adequate maintenance plan, defects must be identified, recognised, and registered. Flexible and rigid pavements have different defects.

The four primary goals of highway maintenance are as follows:

  1. Repairing functional pavement defects helps to prolong the pavement’s functional and structural life. 
  2. Ensure road protection and signage.
  3. Keep the highway in a usable state
  4. Highway systems and all of their components can be kept in initial, as-built condition by following routine maintenance procedures.

Last, but not the least a bit about the safety.

Highway Engineering Safety

Highway engineering safety is important since it involves the life of people. Automated traffic signals can be used to further ensure this.

Highway under construction
Highway under construction
  • Safety management is a comprehensive approach to reducing the frequency and severity of traffic incidents. 
  • The key to improving highway safety is to design, develop, and maintain highway structures that are much more tolerant of the average range of man/machine interactions with highways. 
  • Over time, technological advances in highway engineering have enhanced the methods used in design, construction, and maintenance.

That’s it. Let me know if you need any further details.

Happy learning!