Geometric Design Of Highway And Factor Controlling Geometric Design 2.1

Geometric design of highway:

Geometric design of highway deals with the all the dimensions and layout of visual features of highway such that it provides maximum efficiency and minimum cost and reasonable safety.

The geometric design of a highway depends on several design factor.

The important of these factor which control the geometric elements are:

  1. Topography

  2. Design Speed

  3. Traffic Factors

  4. Design Hourly Volume and Capacity

  5. Environmental And Other Factors

1.Topography or Terrain:

  • The topography or terrain conditions influence the design speed, than in turn governs the designing of highway elements.

  • The classification of topography is based on the cross slope of the country as Plain, Rolling, Mountainous and Steep.

Topography or Terrain Classification
Topography or Terrain Classification
Topography or Terrain
Topography or Terrain
  • For Example in plain terrain On the state highway permissible design speed is 100 km/h, whereas the same speed on rolling terrain is permitted to 80 km/h & on mountain terrain is 50 km/h.

2.Design Speed:

  • Design Speed of vehicle depend upon type of Topography or Terrain Classification and road over which it moves. Example- National Highway, State highway, Major district Road, Other district Road, Village Road and.

Design Speed (kmph)
Design Speed (kmph)
  • Design is speed of vehicle helps in deciding the: cross-section element, width, clearance, side distance, radius of curve, super elevation, transition, gradient, length of the submit curve etc.

3. Traffic Factor:

  • Traffic factor include vehicle characteristics and human characteristics.

  • In order to design highway element standard size of vehicle is consider (car) in case of mixed traffic operation.

  • Human characteristics include physical, mental and psychological characteristic of driver and Pedestrian.

4.Design Hourly Volume & Capacity:

  • The traffic volume fluctuate over the time, hence the designing must be done for peak hours, but it will be high uneconomical to do so.

  • Hence designing is being done for reasonable value of traffic volume termed as “Design Hourly Volume”.

5.Environmental Factor:

The environmental factor such as aesthetics air pollution, noise pollution, landscaping also governs the designing of Highway element.

For Detailed Analysis of Highway Engineering Step By Step.

Highway Engineering

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