Air Transport and Pavement Structures

Air Transport

• Air transport is the fastest mode of transportation in India.
• It is a relatively recent development in India.
• Air transport is the costliest means of transportation, but it provides safe travel over long distances.
• The Indian aviation sector is one of the fastest growing in the world.

Pavement

• A pavement is a structure made up of layers of processed materials above the natural soil sub-grade.
• It distributes loads from vehicles to the sub-grade.
• A good pavement should have sufficient thickness to distribute loads, be structurally strong, provide skid resistance, be smooth, produce low noise, be dust-proof, be impervious, and have a long design life with low maintenance costs.

Types of Pavements

• Flexible pavement: A multi-layer structure with high-quality materials near the surface. It reflects the deformations of the subgrade, sub-base, and base courses on the surface.
• Rigid pavement: Consists mainly of a cement concrete slab with flexural strength, which also serves as a wearing course. It can bridge over local weak spots and deformations without reflecting them on the surface.

Advantages of Flexible Pavements

• Lower initial cost.
• Easy to construct.
• Can be easily repaired.

Disadvantages of Flexible Pavements

• Shorter lifespan.
• Higher maintenance costs.
• Susceptible to rutting and cracking.

Advantages of Rigid Pavements

• Longer lifespan
• Lower maintenance costs
• Greater load-bearing capacity

Disadvantages of Rigid Pavements

• Higher initial costs.
• More complex construction.
• Susceptible to cracking due to temperature changes.

Harbours

• A harbour is a partly enclosed area providing safe accommodation for ships.
• Harbours provide facilities for refueling, repair, cargo loading and unloading, and supply.

Requirements of a Good Harbour

• Road and railway connections.
• Fertile and densely populated surrounding land.
• Sufficient depth for ships in the channels.
• Breakwaters to protect against wave action.
• Secure anchorage for ships.
• Sufficient quays, piers, and wharfs for loading and unloading.
• Fueling, repair, and other facilities for ships.
• Large enough area.
• Cold storage facilities

Types of Harbours

• Natural harbour: Protected by natural land contours, rocky outcrops, or islands.
• Semi-natural harbour: Protected by land contours and requires manmade protection at the entrance.
• Artificial harbour: Manmade with engineered protection from storms and waves.

Site Selection for a Harbour

• Availability of cheap land and construction material.
• Transportation and communication facilities.
• Natural protection from winds and waves.
• Industrial development of the locality.
• Sea-bed, subsoil, and foundation conditions.
• Traffic potential.
• Availability of electrical energy and fresh water.
• Favorable marine conditions.

Harbour Components

• Entrance Channel: Allows ships to enter the harbour.
• Breakwater: Protects the harbour from waves.
• Turning Basin: Provides space for ships to maneuver.
• Shelter Basin: A protected area for ships to anchor or dock.
• Pier: A structure extending from the shore into the water for loading and unloading.
• Wharf: A similar structure to a pier, designed for cargo handling.
• Quay: A concrete or paved waterfront for berthing ships.
• Dry Dock: A basin that can be emptied for ship repairs.
• Wet Dock: A basin with enclosed water for ships to dock.
• Jetty: A structure extending from the shore into the water for access to ships.

Water Conservation Techniques

• Contour Bunds: Built along contour lines to capture rainwater and slow runoff.
• Gabion Structures: Stone-filled cages used to create small check dams across streams.
• Check Dams/Cement Plugs/Nala Bunds: Barriers constructed across streams to slow down runoff.

Dams

• Definition: Structural barriers constructed across rivers, streams, or valleys to store and manage water flow.
• Benefits:
  • Hydroelectric power generation.
  • Water storage for consumption and agriculture.
  • Flood control.
• Drawbacks:
  • Displacement of people.
  • Environmental impacts (habitat disruption, oxygen levels).

Reservoirs

• Definition: A large body of water created behind a dam.
• Functions:
  • Store water for various uses (drinking, irrigation, industry)
  • Regulate water flow for flood control.
  • Recreational opportunities.

Rainwater Harvesting

• Definition: Collecting and storing rainwater for later use.

Domestic Water Quality Requirements

• Safe to drink.
• Free from harmful bacteria and contaminants.
• Pleasant taste and odor.

Urban Roads

• Highways: Major roads connecting cities and towns.
• Arterial roads: Important roads within cities, carrying traffic between major destinations.
• Collector roads: Connect local roads to arterial roads.
• Local roads: Provide access to homes and businesses