CONSTRUCTION OF MODERN ROADS.

   Video on road construction at Taifa-St. John in Accra. Video credit: www.youtube.com.

             Roads are the lifeline of any economically vibrant nation. The road construction revolution has brought to light, the way to globalisation and a marvelous road transport development all over the world. As a result of this, not only is Ghana covering up with the rest of the world in the interconnection of countries but also the interconnection of cities with the best road transport system. Roads can therefore be defined as routes or paths that begin at one destination and lead to another.

A Gravel constructed street. Photo credit: Owusu-Ansah Bridgette.

             Road construction is perhaps one of man's earliest forms of construction. Some of the earliest roads were built by men such as John Metcalfe, a Scotsman who built roads within a distance of 180 miles(290km) in Yorkshire in England. Despite being blind, Metcalfe drained roads and built with three layers consisting of gravel, excavated road material and large stones. Modern tarred roads on the other hand were brought into existence by the works of two Scottish engineers Thomas Telford and John Loudon MacAdam. Telford and MacAdam devised methods of analysing the thickness of stones, road traffic, road alignment and gradient slopes. They also designed a method that involved laying broken large stones in symmetrical patterns and covering them with aggregate in order to create a solidified surface.  Their designs therefore became crucial to the evolution of road construction methods and as such became the standard for road construction projects. Hence a modern road can be defined as a route or way on land which has been paved or improved by the use of modern equipments to allow travel by some conveyance including a horse, cart or motor vehicle.   Roads that are also available for use by the public maybe referred to as highways or public roads. Furthermore, roads that lead into cities and towns can also be referred to as streets, avenues and more.

         Necessity they say is the mother of invention. In this perspective, the manual approach in the construction of modern roads does not seek to only make an impact on the overall quality of roads, but also to improve the condition of life in the society. For the best roads to be built, there are certain processes or steps that are involved which include planning, clearing, leveling, materials to use and maintenance. Before earth-moving machinery can be put to work for road construction, the land undergoes a series of surveys  to determine the route, distance, direction and elevation. This is known as planning. Other important factors to consider in the construction of a road is to know what materials would be used and which methods to employ.

Clearing is the first task after planning in the road construction process. This is done to rid the road of any obstructions that may inhibit construction such as stumps, bushes and rocks. In the early days, these obstructions were removed by hand or with the help of horse-drawn plows. Today, they can be removed by a machine known as the hydraulic excavator which digs the stumps or rocks out of the soil with its long extended arm and bucket.

Leveling the land is the next step after clearing the road. Before the advent of modern machinery, this task was undertaken with hand-held rakes and hoes. Today, this is completed by wheel loaders that remove larger chunks of dirt and rocks and leveled out by motor scrapers. Once the road is leveled, the motor grader is used to create a flatter and smoother surface before the application of asphalt or other materials.

A modern asphalt road. Photo credit: Owusu-Ansah Bridgette.

            Although other materials such as gravel, sand and clay can be used for road construction, asphalt is one of the most common used in constructing modern roads and highways. Some experts recommend using a geotextile  membrane under a soil base to strengthen the surface. The base is then covered by about 9 inches(23cm) of soil,  followed by 6 inches(15cm) of coarse gravel or asphalt. A 4 inch(10cm) thick layer of crushed gravel known as "bank-run" gravel is deposited atop the base. Asphalt roads first appeared in 1824 on the Champs-Elysees in Paris. Asphalt soon became widely used throughout Europe and North America and is now used on 96% of all paved roads in America and also in the world. The first use of asphalt on modern roads however came from the work of Belgian immigrant Edward de Smedt at Columbia University in New York City.


Maintenance of gravel and asphalt roads can be as easy as scraping off the layer of material that covers the road. However, there are certain features of road-building that can aid in the maintenance and longevity of a road. For example, gravel and asphalt two-way roads are recommended to meet at a crown, a raised A-shape or midpoint section of a road. Single lane roads on the other hand do not require them. Also, the best time to pursue reshaping of roads is after rainfalls since the surface is looser and the amount of dust is reduced. This allows the ground to compact more effectively.

         

The newly constructed Madina-Adenta highway. Photo credit: Owusu-Ansah Bridgette.

Today, there are 20 miles(32.3million km) of roadways in the world(as of 2002) with U.S holding the record for the highest number of roadways measuring 3.9 million miles as of 2005. Roads therefore continue and will continue to play a vital factor in modern civilisation with majority of roads being constructed according to city and national standards.