Why are highways planned?

Highways are essential factors that affect urban mobility, and their current conditions are depleting. Accidents are also taking place in huge numbers, and therefore, it is necessary to redesign highways. This could create safe, convenient access for all road users. We can attain environmental sustainability while creating vibrant and livable spaces. The geometric design of the highways should provide accessibility, safety and comfort while preserving the ecology and catering to social concerns. We made them for high-speed regional passengers and for carrying good traffic from inter-city highways or expressways to other inter-city highways which enter the cities at a specific location.

How do we redesign highways for the best urban mobility? - Sheet1
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Need of planning highways

There is a need for planning highways as the capacity of the traffic is increasing day by day. There is an inordinate number of safety and accident problems for which some physical and geometric changes need to be made. Many challenges come up and hamper the process of highway construction like some environmental consequences of the unsuitable location where the highway is being built. The designs are, therefore, re-evaluated many times during the planning phase itself. There are situations when the design speed is slowed down. Also, it is very necessary to maintain a road’s existing horizontal and vertical geometry and cross-section.

Stages of Highway Development

How do we redesign highways for the best urban mobility? - Sheet2
Stages of highway development_©https://external-preview.redd.it/CZSpZqKGVXFCXHAkj263bor3EkZ2uynT6YTEiv4YSJ4.jpg?auto=webp&s=c4e2f1b757c642f8bc30a7137c3fd0a5a2632969

First, the planning is done, and then the project is developed. After they approve the ultimate design, the Right of Way is given, and the construction takes place. The planning occurs at three government levels–state, regional, and local levels. During the planning phase, a survey is carried out, which answers the following questions: – will the proposed highway affect the general physical characteristics of the surroundings? It checks if the area has some unique historic or scenic characteristics and the capacity and cost concerns of the community. Now, it is important to understand the land that is used–what type of character does the corridor have? Are there any destination spots? Is it safe for pedestrians or bicyclists? Is the vegetation sparse or dense? 

After considering and surveying all these factors, we develop a concept. A scale is set, and then the design is detailed. The government purchases additional land as well. The state or the local government may choose the contractor, who then carries out the construction. There are different highway improvement projects, such as: 

  1. New Construction 
  2. Reconstruction 
  3. 3R (Resurfacing, Restoration and Rehabilitation)
  4. Maintenance

Strategies to redesign better highways

Traffic barriers_©https://www.tatasteeleurope.com/construction/products/other/highway-engineering/barriers

The design speed plays a vital role in the construction of highways. It is the maximum safe speed that can be maintained over a specified section of the highway. While they carry out the construction process, this speed needs to be taken into consideration the most. A proper study of the coordination between the horizontal and vertical alignment is required to make up three-dimensional scenarios in mind and hence make the required amendments in the construction as per the situation. One of the best strategies is to achieve the “flowing” line along the natural contours of the river or mountainside. This helps the driver to drive safely and easily.

As the traffic flow is increased, the travel lanes get increased. The desirable lane widths are 3.6 m for both urban and rural settings. It is always good to provide medians as they separate the opposing traffic flow, and provide a recovery area for out-of-control vehicles. They are good as they allow spaces for speed changes and U-turning of vehicles. We also minimized the headlight glare. They should also provide shoulders as they give space for pedestrians and bicyclists when there are no sidewalks. The landscape needs to be planned. They should select such plants that will be an aid to the aesthetics and safety. Some plants also lower the construction and maintenance costs. The native trees could also give a visual edge to the motorists’ driving.  

They place many utilities on the highways. It is better if they are located where they are least likely to be struck by a vehicle. We should bury the power and telephone lines underground. The pole spacing should be increased. Traffic barriers should shield the poles. The traffic barriers that can be used are three strand cable barriers, steel beam barriers, steel-backed timber barriers or stone masonry walls. They should plan more and more intersections or roundabouts as they reduce the severity of potential conflicts between motor vehicles, buses, trucks, bicycles and pedestrians. Bridges and other structures are also a part of the highway construction as they affect the aesthetic, scenic, historic and cultural resources of the corridor.

References:
  1. US Department of Transportation Federal Highway Administration. (2004).Flexibility in Highway Design, pp. 1-130 Available from: https://nacto.org/docs/usdg/flexibility_in_highway_design.pdf (Accessed : 30th July 2022  )
Author

A young architect, and a keen learner who would love to experiment with the intricacy of architecture as per changing environment and the functioning of the society, keeping in mind the sustainability factor and history of the respective place or building.

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