Question: What do bridges and culverts mean?
Answer:
Bridge: When a road or railway is obstructed by a body of water, another road or railway, the structure constructed to cross the said obstruction is called a bridge. Generally, structures built to cross deep water bodies are called bridges.
Question: What is the runway? What does runway length mean? What to consider in determining the length of the runway?
Answer: The rectangular space which is generally paved and used for landing of aircraft at an airport is called runway.
Given the local conditions, the length required for the take-off and landing of the largest aircraft using the runway at an airport is called the runway length.
Factors to consider in determining runway length:-
1. Airport elevation
2. temperature
3. Area information and runway slope
4. For aircraft during flight
5. Length required for landing
Question: What is the basic length of the runway under ideal conditions? What is the effective length of the runway?
Answer: Ideal locations for determining the basic length of a runway are 15°C or 59°F at sea level and zero slope.
The length of the runway along the landing edge up to 60 meters or 200 feet is called the effective length of the runway.
Question: What do you mean by taxiway? What is the sidewalk called?
Answer: The connecting path from runway to apron is called taxiway. This path is used to access the apron after the aircraft lands on the runway.
Sidewalks are pedestrian walkways built along curbs on both sides of city streets. The sides of these roads are built high. As a result, pedestrians are less likely to have accidents. The minimum width of footpath should be 1.5 m. However, if the number of pedestrians is high on a road, its width may be greater. The surface of the sidewalk should be equal to or better than the road surface, so that pedestrians are not inclined to leave the sidewalk and walk on the vehicular road.
Question: How many types and what are culverts?
Answer: Culverts are mainly of four types-
1. Pipe culverts
2. Box culvert
3. Slab culverts
4. Arch Calvert
Question: Write the main difference between bridge and culvert:
Answer:
The difference between bridge and culvert is as follows-
A structure built over a deep body of water such as a river or a large canal, over which heavy vehicles can safely travel is called a bridge. A culvert is a structure built over surface water drainage or small shallow canals across the road, over which light vehicles can move. Sub structure and super structure are constructed separately. Usually sub structure and super structure are built simultaneously. There is no concrete floor under the seed. Under culverts there is usually paved floor.
Question: What is free board? Why is the bridge given free board?
Answer: The vertical distance between the highest water table of a river and the bottom of the girder or springing floor of the bridge is called free-board.
Free board is given on the bridge for the following reasons-
1. For crossing flooded vegetation and other debris.
2. For displacement of waves under bridges.
3. For accommodation of increased water height intercepted by bridge structures.
Question: What is meant by over bridge and flyover?
Answer:
Over Bridge: When two highways or a highway and a railway cross each other at different angles, a bridge is used to cross vehicles. As a result, the lower level road passes under the bridge and the upper level road passes over the bridge, in which case the bridge or structure is called an over bridge. Again the bridge which is made for pedestrian crossing on the highway is called foot over bridge.
Flyover: When two highways carrying 3000 or more vehicles cross each other at the same time, the crossing often faces traffic jams, delays, accidents etc. To remove all these difficulties, the vehicles are arranged to cross separately by constructing bridges. As a result, one road is placed over the bridge and the other under the bridge, such a structure is called a flyover.
Question: What is tar and asphalt?
Answer: Destructive distillation of organic materials (coal, oil, wood) in the absence of air produces tar as a by-product.
Asphalt: Mineral bitumen mixed with inert materials is called asphalt.
Question: Write the difference between asphalt and tar.
Answer: The difference between asphalt and tar is as follows:-
Asphalt:
1. Asphalt is obtained as a byproduct of the partial distillation of crude petroleum.
2. Asphalt is not easily coated on aggregate surfaces and does not stick to wet surfaces in the presence of water.
3. Asphalt water resistance is very good.
4. Asphalt is less sensitive to heat, so there is little change in viscosity with temperature variations.
5. Asphalt is soluble in carbon di sulfide (CS₂) and contains less free carbon than tar.
6. Asphalt has no toxicity.
7. Asphalt sets faster than tar.
8. Suitable for asphalt road works.
9. Cost is higher than asphalt tar.
10. Asphalt is solid or semi-liquid at normal temperature.
11. Cracks are not usually seen on coated surfaces.
Tar:
1. Tar is produced through the destructive distillation of coal and wood.
2. The tar is easily coated on aggregate surfaces and adheres fairly well to wet surfaces.
3. Its water resistance properties are poor.
4. Tar is very sensitive to heat. As a result, variations in temperature cause large variations in viscosity.
5. Tar carbon di sulfide (CS₂) has a higher soluble and free carbon content.
6. Tar is toxic due to the presence of phenol
7. Tar sets more slowly than asphalt.
9. Tar is cheaper than asphalt.
10. Tar is liquid at normal temperature.
11. Cracks appear on the tar coated surface.
8. Useful for tar pits and canopies.
Question: What is rail gauge? Write the sizes of different types of rail gauges.
Answer: The distance between the inner edge of one rail and the inner edge of the other is called rail gauge.
Gauge Sizes:
1. Broad gauge..... 1676 mm to 1524 mm
2. Meter gauge..... 1067 mm to 1000 mm and 915 mm
3. Narrow gauge.....762 mm and 610 mm
4. Standard gauge.....1435mm and 1451mm
Question: Where should which type of gauge be used?
Answer:
Usage of Gauge:
1. Broad gauge and standard gauge should be used for long and high speed lines.
2. A meter gauge should be used on the medium line.
3. Narrow gauge should be used in hilly and industrial areas.
Question: What do you mean by train movement? Explain what causes the train to move.
Answer: Movement along the length of the rail due to train movement is called movement or creep.
Reason for moving:
1. Pressing the brake causes movement.
2. The wheel moves for wave motion.
3. Changes in temperature cause the rail to move.
4. If the connection of the rail with the side is not good, movement occurs.
5. If you don't use a good quality filter, it moves.
6. Movement occurs if proper super elevation is not given.
7. If the side spacing is not correct.