History of Roads

Since the invention of the wheel over 5,000 years ago, it had crossed the minds of our ancestors the need for hard surfaces for them to move from one place to another. The earliest hard surface ever recorded in history was arguably the stone-paved road which was constructed to facilitate moving huge limestone blocks for use in building the Great Pyramid. The road was constructed by piling up and arranging broken rocks to form a flat and solid surface.

It was also recorded that the road in the town of Ur in Iraq which was made with broken stones and another that was built using tree trunks which were kept submerged in a swamp in Glastonbury, England in 4000 BC could also be among the first road structures ever built.

Later in 520 – 485 BC, King Darius I of the Persian Empire built a 2,400-km long road, for use by his military troops. In 322 – 298 BC, Chandragupta constructed a road network across the sub-continent of India. Upon completion, he set up a special ministry to manage and carry out maintenance works.

The 16th century recorded the rapid development of roads. Towards the end of the 18th century, a number of prodigies such as Pierre Tresaguet, Robert Phillips, John Metcalf, Thomas Telford and John McAdam contributed considerable engineering skills in road construction. During those days, boulders, pebbles and sand were used as construction materials whereas water was used as binders. John Metcalfe, a Scottish who was visually impaired, had built a road over 180 miles long in Yorkshire, England. The structure consisted of three layers comprising large boulders, road construction materials excavated from elsewhere, and small stones. Modern tar roads could be attributed to the Scottish too, namely Thomas Telford and John McAdam.

Bituminous road surfacing, used worldwide nowadays, is attributed to John McAdam, widely recognised as the first highway engineer. His concept of building roads which is as valid today as it was over a century and a half ago was ‘to put broken stones upon a road which shall unite by its own angles so as to form a solid hard surface’. To reduce dust and the need for repair work, tar was later discovered and introduced to bind the stones. Thus, this mixture was commonly known as tar macadam. 

The modern asphalt road was invented by Edward de Smedt, an immigrant from Belgium who was a student at Columbia University in New York. By 1872, de Smedt had produced a 'well-graded, maximum density' asphalt. This asphalt was used for the first time at Battery Park and on the street of Fifth Avenue in New York in 1872 and on the streets of Pennsylvania Avenue in Washington in 1877.

In Malaysia, the paved road network has been constructed over a period of approximately 80 years. At present, the total length is approximately 180,000 kilometres. 

In the 1940’s, paved roads in this country were mainly semi grout and surface dressing. Bitumen macadam was only introduced in the 1960’s. Subsequently, based on the Malaysian Highway Maintenance Study which was completed in 1967, asphaltic concrete was adopted by the Public Works Department.

Asphaltic concrete consists of a continuously graded mixture of coarse aggregates, fine aggregates and mineral filler, mixed with bitumen. The composition is determined by a standard mix design procedure. The mechanical strength of the mixture is largely obtained from the interlocking of aggregate particles held together by the bitumen.

The evolution of asphaltic concrete mix design and application shows the following trend; initially the mixture was prepared with a relatively high content of bitumen. As traffic intensities increased, particularly in the post-war era, the road surface was severely subjected to secondary compaction by traffic until the air voids in the mixture became filled with bitumen. The bitumen flushed to the top causing the road surface to become unstable and slippery. Bitumen contents were then steadily reduced and it was at this stage that mix design procedures became popular. The general reduction in bitumen content appeared to have reduced failure due to secondary compaction by traffic but it increased the number of early cracking caused by hardening of the bitumen. 

Relatively small size crushed rocks, referred to as aggregates, are the largest component of the asphaltic concrete mixture. Usually, around 95% of the mixture is made up of aggregates. The role of the aggregates is to accommodate the traffic load before it is transmitted to a thicker layer of road base underneath. Aggregates are subjected to all types of physical aggression such as being tumbled, knocked, dragged, compacted and abraded during the production of asphalt at mixing plant, paving at site, and subsequently exposed to traffic.       

Aggregates with their mechanical and physical characteristics, and the interlocking between the particles, play a pivotal role in providing a strong pavement layer to support traffic loading and provide resistance to deformation.