Road Construction Methods


The load-carrying capacity of a road surface depends on continuous, stable support furnished by the subgrade. Subgrade stability requires adequate drainage and proper load distribution by the surface and base courses. Surface and base courses of sufficient thickness and quality to spread the wheel loads over the subgrade are necessary so that the applied stress is less than the unit load capacity of the subgrade. In areas where seasonal freezing and thawing occur, the load-carrying capacity of inadequately designed or improperly constructed roads can be dramatically decreased to the extent that failure may occur. Road Construction Methods have changed a lot since the first roads were built in about 4000 BC. Read on to learn more about road construction methods and procedures.

Road selection and design depend on the nature of the subgrade; the traffic and drainage conditions; the construction time available; the supply of local and imported materials; and the engineer equipment, personnel, and expertise available. The completed design must then meet the requirements for the given load class and allow safe and efficient traffic movement.

In ancient times, river transport was much faster and easier than road transport. The Romans were one of the first to build stone paved roads in North Africa and Europe to support their military operations. Later the Arabs built roads that were covered with tar. The roads were constructed by preparing earthworks and lifting the road foundation at the center for water drainage. Road construction techniques gradually improved by the study of road traffic, stone thickness, road alignment, and slope gradients. Initial road construction materials were stones that were laid in a regular, compact design, and covered with smaller stones to produce a solid layer.

The building techniques were simple but effective as they reduced the travel time considerably and connected one place to another by land. The Appian Way in Rome still exists although it was constructed 2300 years ago. If Roman roads are considered the beginning of road construction, Telford Pavements are known as the second step of this process, followed by the Macadam Pavements that ultimately lead to the Bitumen Roads. Today, the concrete roads have added another dimension to stability and strength of the roadways.

Road Construction Techniques
Modern road construction involves the removal of geographic obstacles, and the use of new construction materials that are far more improved and durable. Rock and earth is removed by explosion or digging. Embankments, tunnels, and bridges are constructed, and then vegetation is removed by deforestation, if necessary. Finally, the pavement material is laid by using a range of road construction equipment.

Roadways are basically designed and constructed for use by vehicles and pedestrians. Storm drainage and ecological considerations should be considered seriously. Sediments and erosion are controlled to avoid damaging effects. Drainage systems are constructed so that they should be able to carry waste water to a waterway, stream, river, or the sea.

Importance of Earthwork
Earthwork is one of the major works involved in road construction. This process includes excavation, material removal, filling, compaction, and construction. Moisture content is controlled, and compaction is done according to standard design procedures. Normally, rock explosion at the road bed is not encouraged. While filling a depression to reach the road level, the original bed is flattened after the removal of the topsoil. The fill layer is distributed and compacted to the designed specifications. This procedure is repeated until the compaction desired is reached. The fill material should not contain organic elements, and possess a low index of plasticity. Fill material can include gravel and decomposed rocks of a particular size, but should not consist of huge clay lumps. Sand clay can be used. The area is considered to be adequately compacted when the roller movement does not create a noticeable deformation. The road surface finish is reliant on the economic aspects, and the estimated usage.

Bulldozers are some of the most important items of equipment used in road construction. Since a bulldozer is expensive, economic usage factors should be considered when using one. Bulldozers are extremely useful for road construction where it is possible to throw the waste excavated material on the road sides. Bulldozers may only be used if the slopes at the sides are not excessively steep. However, work on steep slopes can be accomplished by a bulldozer by using special techniques and expertise.

Construction of roads in challenging conditions is no more a difficult tasks because the binding agents and admixtures make it possible for the roads to last long and carry the heavy loads without cracking under tough environmental conditions. Use of recyclable materials for the construction of roads has added balance to the enviroment too.

Construction Management of Roads
With ever increasing traffic and exponentially increasing vehicular load, construction management techniques have become the need of the hour. Managing maximum traffic in optimal space is what the world needs today. Safe designing of roads, highway space management and proper drainage of water are major aspects that the site engineers have to take care of. Construction management includes putting all the pieces of puzzle together, defining project objectives, dividing the project into modules and optimizing the available resources. Time, money and resource management are important aspects. Time saved is money earned, and that is where construction management techniques are helpful.

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