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Basic Requirements of Road Alignment and Its Contributing Factors

25 March 2022

The condition of a community relies heavily on the existence of roads. Roads are areas where vehicles and other means of transport can traverse. Since they move people and products from one point to another, socio-economic developments grow effectively, especially if the roads are designed well.

One activity that can ensure the proper design of roads is road alignment. Road alignment is the placement of a road’s centreline. It dictates the direction in which the road will go and pass, preventing conflicts that often contribute to heavy traffic and frequent vehicular accidents or collisions. It likewise establishes the best way to construct roads without wasting valuable resources.

Road Alignment Requirements

There are various requirements that contractors must account for in a road alignment.

  • The road alignment must be as short as possible to minimise expenses for the construction.
  • A road must be as straight as possible so that the traffic can reach higher speeds.
  • The road alignment must be easy for contractors to construct, maintain, and operate the road.
  • The alignment of the road should cross railway lines, bridges, rivers, canals, streams, and roads at right angles and other dimensions.
  • The road alignment must serve areas that are heavily populated. Hence, bridges, crossing culverts, and embankment places must be passed by roads.
  • The alignment of the road must not pass through places where natural scenery is present.
  • The road alignment must not be obstructed by ponds, lakes, wells, historical buildings, monumental buildings, and other important structures and resources.

Key Factors of Road Alignment

The quality of road alignment relies on the following key factors.

  • Purpose: National and state highways and roads must be aligned straight since they are used as major routes for most vehicle types. Other types of roads, alternatively, can possess a deviation.
  • Obligatory Points: Obligatory points determine which places the roads can or cannot pass through. Roads can pass through vital communities and areas. Roads cannot pass through historical places, cultural places, and areas that are filled with natural scenery.
  • Type of Traffic: Road alignment must be straight for fast-moving traffic. Alternatively, road alignment for low traffic can be comprised of sharp turns.
  • Sight Distance: Drivers of various vehicles should attain a clear sight distance to avoid vehicular accidents and collisions.
  • Gradient: Road alignment should have a deviation from the straight line to ensure that their longitudinal slopes won’t be sharper than the ruling gradient. 
  • Horizontal Curves: National and state highways must have at least 230m of horizontal curve radius.

Advantages of Road Alignment

Tons of advantages await roads that will be aligned effectively.

For one, proper road alignment can lead to lower cases of accidents. Since roads are strategically planned, vehicles have a lower chance of colliding with others on intersections, curves, and other road points. Another advantage of road alignment is it can cut construction and maintenance costs. The planning of road alignment can prevent repetitive construction and maintenance processes that require repetitive expenses. Even the operating costs of vehicles can go down through proper road alignment.

Ultimately, road alignment that is done properly can increase the durability and longevity of the roads. Road construction projects can be expensive. And so, to make sure that they last longer, contractors have to carry out road alignment properly and strategically.

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