Highways are the main public roads that connect different cities, towns and at times, villages etc. together. It is a major and significant public road that is able and fit to carry fairly heavy traffic. Since automobile has gained popularity in the world today, the need for adequate and efficient transport system for promoting economic development is a notable fact that cannot be underemphasized. Substantial investments on road infrastructural development by government at different levels e.g. Federal, State and local government are also frantic efforts to attract investors which will in turn promote the economy.
Highways have great benefits to industries, educational institutions, tourist centres, hospitals. It plays an indispensable role in the economy of both the developed and the developing countries of the world in making travels easier and faster. Hence, any problem that may affect smooth transport operations on highways may have great negative impacts on the economy of a nation at large.an important thing is also that Highway networks make transportation schedules and deliveries more reliable and timely. It reduces the cost of vehicle maintenance, when you compare it to vehicles subject to extraordinary rough physical treatment under poor road condition.they also increase the life-span of a vehicle: Under poor road condition tires, brakes, clutches and other vehicle parts suffer when moving on a bad road. But when the roads are good the vehicle’s parts function well over a good period of time.
An important point is also that they help to reduce accident rate. The life of any individual road user is important. Good roads help to reduce rate of accident that may come as a result of bad roads. For instance, highway constructed to link Tibet one of the provinces in China was said to have reduced accident rate in the area by 40%. (1)
this why it is imopartant to have regular Inspections on the roads cause for example In Germany, many highways suffer of the so called “concrete cancer”. Many highways have to be refurbished, even though they haven’t reached the end of their planned lifetime. This chemical process is an alkali-silica reaction, where a gel forms in the concrete that expands creating tensile forces in the concrete matrix which cause cracking of the concrete. The cracking then allows more water to infiltrate into the concrete creating more gel, more expansion etc. Ultimately the concrete fails or disintegrates. Typical indicators of ASR are random map cracking and, in advanced cases, closed joints and attendant spalled concrete. Cracking due to ASR usually appears in areas with a frequent supply of moisture, such as close to the waterline in piers, near the ground behind retaining walls, near joints and free edges in pavements, or in piers or columns subject to wicking action. Petrographic examination can conclusively identify ASR. (2)
to avoide this problem and other road problems Asphalt Surface Maintenance is recomended every 8 years and a Asphalt Surface Replacement every 20.
A common road construction on German highways and federal roads has been chosen. The most common material for this is asphalt, a mixture of aggregates, binder and filler. Most commonly, bitumen is used as a binde
The Figure left shows the typical road layers of a highway or federal road in Germany. As you can see, every layer has a different thickness and consistsof a different material. The asphalt layer differs in terms of corn size, in which the asphalt surface has the smallest composition and is therefore most susceptible to external influences.In Germany, 95 % of road surfaces are made of asphalt. There are many different types, but the most common are Asphalt Concrete (AC),Stone Mastic Asphalt (SMA) and Mastic Asphalt (MA).
Subsystem: Road surface
In the second assignment, three options were considered for the road surface, stone mastic asphalt (SMA), recycled asphalt (RA) and open-pored asphalt (PA). SMA is the type of asphalt most used in Germany and is suitable for almost all roads. RA is very similar to SMA, but in contrast to it, it has a significantly higher proportion of recycling material. This is obtained again from recycled aggregate. The PA is a very special type of asphalt and is only used in special cases. It has a much more open structure, which results in a reduction in smoke. Unfortunately, it is therefore very susceptible to fatigue and has a significantly shorter lifespan.
Since recycling material in road construction has a slightly lower consumption of energy and emits slightly fewer emissions, this has emerged as the best material in the second assignment and is now used for the third assignment.
For the integrated system, a two-layer asphalt structure consisting of asphalt surface and asphalt binder or base course was used to create a realistic scenario. It will be interesting to see how this change will affect the whole system.
(1) https://globaltransportandlogistics.com/12-benefits-of-highway/