Main Components of Highway Design | Highway Construction
The width of the road, road pavements, curbs, traffic separators, road margins, cross slopes, and others are the main components of the Highway design. These design elements have been made based on the influence of the driver’s psychology along with the traffic of the region and the characteristics of the road. These components should be managed in a skillful manner to ensure the safety of the highway.
The main components of highway design are elaborated below:
Road Pavement design
This is one of the expensive working procedures during the construction of highways and the repair work of road pavement is also expensive. The fundamentals of the pavement plan are critical to understanding by highway engineers. A paved surface aids help to assist the drivers by giving a visual presentation of the perpendicular and horizontal alignments of the travel path. This paved surface aids also helps to give information to the drivers about their driving tasks as well as the steering control of the vehicles. The automobile loads have been also supported by the road pavements.
Road Pavement design
There are different types of road pavement designs available which are:
Rigid pavement design
This is the Portland cement concrete pavements. This type of pavement design has been used in airports and major highways. The service life of rigid pavement design is generally 30 to 40 years.
Flexible pavement design
Flexible pavement is the Asphalt pavement which is made of 3 to 4 layers. The service life of this flexible pavement is 20 to 30 years.
Rigid pavement overlay design
This type of pavement design has been made with the purpose of renovating the old rigid pavement or worn-out pavement. This rigid pavement overlay design was made before the expiration of the old rigid pavement’s service life.
Flexible pavement overlay design
These types of overlay designs have been made on the flexible pavements. Portland cement concrete, asphalt concrete, and ultra-thin Portland cement concrete are used in this type of overlay pavement design.
How to measure the quality and performance of the pavements
The pavement serviceability index (PSI) helps to determine the condition of the pavements by providing insights into the pavement’s performance level and quality. In addition, friction measures, international Roughness Index, and rut depth are other important parameters that can be used and monitored by highway pavement agencies to measure pavement quality and performance.
Roadway width
The width of the roadway can be measured by doing the sum of the width of the pavement and the shoulders of that roadway.
Road margins
Road margins
Road margins also include several design components which are:
Shoulders
Shoulders are located on the edge of the highways. The function of this area is to serve the accommodating vehicle’s purposes which are taken out of the roadway pavement. For those vehicles that are broken down, shoulders act as the service lane.
Parking lanes
This component has been provided for the construction of urban roads. Parking lanes help to allow curb parking.
Bus Bays
The recession of the curbs has constructed these components.
Sidewalks or footpaths
In the case of heavy traffic including vehicular traffic and pedestrian traffic, sidewalks or footpaths can be used for pedestrians. This area helps to reduce the chances of accidents by protecting pedestrians.
Sidewalks or footpaths
Curbs
Curbs are designed and constructed for urban roads. This design component is the boundary between the shoulder of the road and the pavement of the road.
Curbs
Medians
These are the traffic separators. Medians help to prevent the collision of vehicles on the highway that are moving in the opposite direction on the adjacent lanes.
Medians
Cross slope
Cross slopes are also known as camber which are provided in the transverse direction of the pavements. The rainwater can be drained from the surface of the road with the help of the cross slopes. In the case of inadequate cross slopes, the flooding of water over the road pavement can occur.
This overflow or flooding of water leads to the deterioration of the highway. In this regard, cross slope is crucial to maintain the serviceability of the highways. The types of materials that are used in the construction of the roads and the amount of rainfall in that region are the most important factors in measuring the value of the cross slope. In general, the value of the cross slope has ranged between 1 in 60 to 1 in 25.
Cross slope or camber
Right of way
The right of way indicates the land area that is acquired for the road along with the alignment of the roads. The width of the land refers to the land width that is acquired by the road. This factor depends on the future development possibility of the roads and the importance of those road.
Right of way
To get more details, watch the following video tutorial.
Video Source: Practical Engineering
Highway alignment
The concept of highway alignment refers to horizontal alignments, on the other hand, the elevation of the highways in the profile view has been estimated as the vertical alignment of the highways.
Horizontal alignment
In horizontal alignment, the horizontal curve is the most crucial part. The transition between the two tangent segments of a road has been referred to as the horizontal curve. The construction of the horizontal alignment by the civil engineers should be done to manage the abilities of different types of trucks including agile sporting cars and massive cars.
Vertical alignment
The vertical alignment indicates the altitude of places along with the roads. These spots are elevated to promote the comfort and safety of motorists as well as promote the drainage system of the roads. In this case, the transition of the heights of the highways is difficult which is made with the vertical curves.
