Topic of- Super elevation, Camber and Gradient, Ruling gradient and floationg gradient, junction or intersection, sub-grade, traffic signs, cement concrete roads, pavement, bitumen, cut back, dowel bar, Tiber
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Question: What is super elevation?What does it require?
Answer: Centrifugal force and own weight of the car act on the curved car.Centrifugal force causes the car to overturn.To overcome this difficulty, the outer side of the curved road is built higher than the inner side.This amount of elevation is called super elevation.
Requirements of Elevation:
1.Protecting the vehicle from accidents.
2.Bending water for faster speed drainage.
3.Protect from unwanted jolts while traveling.
4.Prevent road damage.
Question: Where and why is super elevation used?Super elevation is dependent on what factors?
Answer: Super elevation is generally applied to road or rail track bends.
Considering the speed of the vehicle and the angle or radius of the turn, the value of the first centrifugal force is greater than the deviation of the vehicle from the roadway.The road is raised from the inside to the outside to prevent it from tipping outward so that the centrifugal force and the weight of the vehicle and the frictional force are in balance.
Factors on which super elevation depends:
1.Vehicle speed
2.Bend radius
3.Road width
4.road slope
5.Coefficient of friction between car wheel and road
6.Acceleration due to gravity
Question: What is camber and gradient?What are the camber requirements?
Answer: The transverse slope of the road surface is called camber.This is called cross slope.
The rate of improvement or deterioration of the surface with horizontal distance along the length of the road is called gradient or vertical slope.A 1:100 slope means a 1 meter rise or fall over a 100 meter horizontal distance.
Camber Requirements:
1.Rapid drainage of water from the road surface.
2.Keeping road pavement dry.
3.Keeping the road suitable for vehicular movement at all times.
4.Reducing road maintenance and repair costs.
5.To enhance the aesthetic beauty of the road.
6.Assisting the vehicle to move in two lanes.
Question: What is meant by ruling gradient and floating gradient?
Answer: The slope on which the vehicle can easily ascend and descend is called the ruling gradient.Climbing such slopes consumes additional engine power and does not require brake power during descent.
The slope of the slope is called floating gradient when a vehicle enters a downward slope at a certain speed and is able to cross the slope smoothly without using brakes or engine power.
Question: What is a road junction or intersection?What is its purpose?
Answer: When three or more roads coming from different directions cross at the same plane or intersect each other, it is called a road junction.
Purpose of the Treaty:
1.Development of vehicular traffic.
2.Avoiding a head-on collision between two vehicles.
3.Improving road efficiency.
4.Directing the vehicles on a certain route.
5.Avoid wastage of national funds by building fewer roads.
Question: What is sub-grade?What are the considerations in sub-grade construction?What is the function of sub-grade?
Answer: A layer of soil some depth below the surface of the sub grade that serves as the foundation of the road structure is called sub grade.
The issues in sub grade construction are-
1.Balanced grading of soil and gravel
2.Status quo power
3.Good drainage quality
4.Ability to gain full power after compact
5.Tested by stabilization method
Sub grade work:
All loads on the road are transferred through the different layers of the road and fall into the sub grade.That is, the sub-grade carries all the loads falling on the road.
Question: What are traffic signs?How many types and what are they?Why are traffic signs used?
Answer:
All the signs or signals used on roads to regulate the speed of traffic are called traffic signs.
Traffic signs are generally divided into three categories, namely-
1.Warning signs
2.Mandatory marks
3.Informational signs
Traffic signs are used to make the road and traffic safe by controlling the vehicles plying on the road through traffic signs.
Question: What is the classification of cement concrete roads?What is pavement?What are the parts of road pavement?
Answer: Cement concrete roads are of different types,
Example-
1.Cement concrete slab pavement
2.Cement grouted macadam pavement
3.Cement Bound Macadam Sandwich
4.Crete Way
Pavement: The part of the road on which the vehicle moves is called pavement.
The parts of road pavement are-
1.Sub-grade 2.Sub-base 3.Base Course 4.Waring course.
Question: What is bitumen?What is the classification of bitumen roads?
Answer: Bitumen is a black or brown colored organic substance, obtained by artificial means of breaking down parts of crude petroleum.Chemically, it is a mixture of hydrocarbons that are solid or semi-solid at normal temperatures.It can be firmly attached to the stone core.
Classification of bitumen roads:
1. Surface dressing and painting
2. Seal coat, Tack coat, Prime Coat
3. Penetration
4. Full growing
5. Semi-growing
6. Premix construction
7. Bound macadam
8. Bituminous concrete
9. Mastic asphalt
Question: Why is bitumen used in road construction?What is cut back?
Answer: Bitumen is used in road construction for the following reasons-
1.To obtain a waterproof road surface
2.For joining together road metals
3.To achieve weather resistant properties.
Cutback: Mixing volatile solvents or high boiling point light oil with bitumen to reduce viscosity is called cutback or cut backing.
Question: What is a dowel bar?Why are dowel bars used?
Answer: At transverse joints of concrete road, stir rods are used at fixed length and spacing between the slabs to transfer the load from one slab to another slab.Half of its length is firmly fixed to one side of the slab and the other half is slid-ably placed on the other slab coated with grease or oil.Dowels are repeated in such a rod.Slippery metal caps are used in expansion joints.
Reasons to use Dowel Bar:
1.To compress and expand the slab independently.
2.Transfer the load uniformly on the slab.
3.To hold together naturally.
4.To resist maximum expansion.
Question: What is the Tiber?What is stabilized soil road?Name 10 tests of bitumen as a road construction material.
Answer: In case of longitudinal joints, steel rods are attached at fixed intervals of fixed length to hold the slabs together.Its block side is firmly attached for half its length and the other half length is lubricated and slid ably placed.It is called the Tiber.
A stable road made by mixing and compacting two types of soil around the road such as sandy soil and clay soil with or without admixes is called stabilized soil road.Lime, cement, calcium chloride, resin are used as admixes in stabilization.
The names of 10 tests of bitumen as a material in road construction are as follows:
