Highway Engineering Lecture 1: Road Construction Development PDF

University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Highway Engineering Lecture 1: Road Construction Development University of Kerbala College of Eng....

University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Highway Engineering Lecture 1: Road Construction Development University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Over the course of history, human activities have developed and increased day by day. Consequently, this has raised the need to transport people and goods from one place to another. The invention of the wheel in Mesopotamia in about 5000 BC and the development of the axle that linked two wheels (O’Flaherty, 2007), contributed to the evolution of civilizations by facilitating communications between different communities and increasing the exchange of goods and the sharing of ideas and experiences.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Historically, the Babylonians built the earliest roads using natural asphalt as a binder; also the Egyptians constructed roads to transport stones during the building of the pyramids (Watson, 1994). The Chinese built the Silk Route, which is amongst the best known roads, in about 2600 BC; and the Persian Empire also benefited from this route through its lands for trade between China and Europe (Kendrick et al., 2004). In Europe, in about 2500 BC, roads were built using log-rafts; such roads have been discovered in Britain: one crosses the Somerset peat bogs to Glastonbury. Also, similar roads have been discovered in the Swiss Lakeside Villages and across the Pangola Swamps in Hungary (Kendrick et al., 2004). In Indian civilization, brick paving with proper piped surface water drainage systems dating from about 3000BC has been discovered.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Historically, the Babylonians built the earliest roads using natural asphalt as a binder; also the Egyptians constructed roads to transport stones during the building of the pyramids (Watson, 1994). The Chinese built the Silk Route, which is amongst the best known roads, in about 2600 BC; and the Persian Empire also benefited from this route through its lands for trade between China and Europe (Kendrick et al., 2004). In Europe, in about 2500 BC, roads were built using log-rafts; such roads have been discovered in Britain: one crosses the Somerset peat bogs to Glastonbury. Also, similar roads have been discovered in the Swiss Lakeside Villages and across the Pangola Swamps in Hungary (Kendrick et al., 2004). In Indian civilization, brick paving with proper piped surface water drainage systems dating from about 3000BC has been discovered. University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Actually, the most professional roads were built by the Roman Empire around 312 BC. The Romans built 29 major radial roads to connect Rome to other cities and encampments (O’Flaherty, 2007). Generally, they cut deep ditches, then layers of chalk, flint, sand and gravel were constructed to form embankments beneath the final surface, which was finished with huge stone slabs. Figure (2-1) is example of a paved Roman road. The Roman roads system extended as a loop from Spain through France, Germany, Italy to Turkey, also through Syria to Tangier in the north west of Africa. The total length of the roads system was approximately 78000km. However, this roads system represents the most organized roads system until the 17th century in Europe. University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Figure -1 Roman Road Structure, (Kendrick et al., 2004) University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan The development of the coach during the 16th century led to the start of stagecoach services between Edinburgh and Leith in 1610. Also, steady development in manufacturing industries during the 18th century put huge pressure on the British Parliament, which responded by passing a number of statutes aimed at improving and extending the road network. By 1706, over 1100 Turnpike Trusts had been created, with responsibility for 36,800 km of roads. The duties of these Trusts were constructing and maintaining a specified road length, also to levy tolls upon certain types of traffic. At the same time, France had applied the same Roman construction principles to build streets in Paris and elsewhere in France. University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan During the 18th century a new road builders’ era commenced, started by Robert Phillips when he submitted his suggestion “A dissertation concerning the Present State of the High Roads of England” to the Royal Society in 1736. Phillips suggested a solid road surface of a beaten gravel layer resting on a well-drained base. Another well-known English road maker was John Metcalf, who built 290 km of roads in Yorkshire. Metcalf believed in good foundation and drainage; he arched carriageways to help surface water drainage; also, on weak/soft ground, he used a sub-base raft of bundled heather, Figure (2-2). Figure Error! No text of specified style in document.-2 Metcalf’s road structure, (Kendrick et al., 2004)  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Additionally, the contributions of two Scottish road engineers, namely Thomas Telford and John Macadam, were extremely important in the development of road construction methods and traffic stream carriages; for the first time, roads were being built to suit the requirements of the traffic. Regarding construction methods, Macadam’s varied from Telford’s in that the formation was shaped to the road camber, while the sub-base was formed to camber in Telford’s method - see Figure (2- 3). Also, Macadam’s method was a cheaper form of construction. Telford’s method Macadam’s method Figure Error! No text of specified style in document.-3 Telford’s and Macadam’s road structures, (Kendrick et al., 2004) University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Road development was negatively affected after the first operation of the railways in 1825, as the numbers of passengers who were using stagecoaches started to decrease continually; consequently the Turnpike revenues decreased. However, at the beginning of the 20th century, and especially after the end of World War One, attention to the development of roads and highways was renewed; this interest in road development resulted from the development in motor vehicles. The development started with the spreading of tar on roads to control dust created by vehicles’ movement and then to reconstructing existing roads.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan However, the development in vehicles in terms of extra weight and speed has led to the need for new roads and highways; as a result, for example, dual carriageway roads were constructed and road geometric designs were advanced. Also, vehicle development put a huge stress on pavement constructors to build structures that could resist high stresses and bad weather conditions. Accordingly, construction techniques were advanced; more structural layers were built; and the structural layers and subgrade were compacted using different materials to improve their mechanical properties. During the 20th century significant developments in road and highway construction were achieved to satisfy the traffic requirements. Today, roads and highways represent a great achievement, but of course the development will not stop and continued developments are still in demand.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Pavement Structures The main purpose of the pavement or pavement layers is to minimize stresses generated by traffic on the subgrade to such a level where no deformations occur. Simultaneously, the pavement layers themselves should be withstanding the stresses and strains which are imposed on each layer for the entire life of the pavement. Typically, modern pavement structures are either flexible, rigid or a composite of the two. As can be seen in Figure (2-4), normally bituminous, hydraulic bound or concrete layers are built on foundation courses depending on the design decision. The decision and selection of course and layer type is generally dependent on common practices, availability of the materials, site characteristics, etc. University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan It should be known that a layer is an element of a pavement laid in a single operation, while a course is a structural element of a pavement constructed with a single material; a course may be laid in one or more layers. However, construction of the pavement normally starts with enhancing the subgrade “natural soil” bearing capacity by compaction, and then layers are constructed one by one. A capping course may be constructed over the subgrade depending on the site terrain, and then the sub-base course is placed; both capping and sub-base form the pavement foundation.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan In a rigid pavement type, a quality concrete layer is normally constructed over the foundation; in some cases a base course is used. The concrete slab could be reinforced or plain concrete; also it could be jointed or continuous. Rigid pavement is preferred for some sites such as petrol stations and heavy vehicle lots. Additionally, a bituminous layer could overlay the concrete course, mainly to enhance ride quality in terms of noise: this pavement structure is called composite pavement.  University of Kerbala College of Eng. Highway Engineering Department of Civil Eng. Dr. Shakir Al-Busaltan Flexible pavement courses over the foundation may include base, binder and surface courses. The base course is the main structural element and it could be constructed from granular material which may sometimes be mixed with hydraulic or bituminous material. Binder and surface courses are bituminous mixtures; the surface course is exposed directly to weather and traffic actions, so this course should withstand traffic loading, weather action and wearing from tyres. Furthermore, the surface course has to provide high riding quality and sufficient skid resistance. Flexible pavements represent the majority of paved roads globally. In Europe and North America, more than 90% of roads and highways are surfaced with flexible pavements (NAPA and EAEA, 2011), due to their unique high quality and riding quality, together with the lower cost compared with other pavement types.