Vertical Crest Equations - Thesis Example

Current road network systems require proper and detailed construction to ensure they last long and also handle different vehicles using the road. There are different types of roads. These include stone paved roads, timber track ways, and brick paved roads, tarmac roads among other types of roads. Tarmac roads are most the most common types of roads in the modern world. Road construction is normally controlled by the public sector. Road building is a capital intensive exercise and most roads are accessible to the general public.

Road construction involves the making of a continuous path with low grade of stone to allow for passage of vehicles and humans on foot. it begins with removal of vegetation, followed by digging or rock excavations for areas with rocks. The pavement material is then laid. Proper optimization must be done to ensure minimum cut and fill. Road building process encompasses the removal of the top layer of unwanted soil by excavations. Filling the excavated trench with hardcore stones, compacting the stones, lying of tarmac and finally compaction of the tarmac.

During road construction several environmental aspects have to taken into consideration. First roads generate considerable air pollution due to cars emissions. Secondly the urban rainfall cumulates to form runoff that flow along the hard surface collecting chemical and metals which end up in /major water bodies. Noise pollution is also common to people living near major highways. During road construction, there are number of geographical obstacles experienced by the engineers and the design engineer has to figure out how to overcome these obstacles in the most effective and economic way.

One common problem is when designing a road in hilly areas or in areas with sharp decent and ascent. Care must be taken to ensure that the driver can see ahead especially during the nightVertical curves In the design of highways, there are various fundamental transition elements. These include the horizontal and the vertical curves. The vertical curve is important as it provides the transition between two roadways. This allows the vehicle to negotiate the elevation gradually rather than a sharp cut.

These vertical curves are used to connect roadways with inclined sections and provide transitions between two grades. They are easy to design as the only requirement is to determine the length of the curve that will accommodate the required sight distance. Type's of vertical curves According to the Department of transportation, There are two main types of curves, the sag curve and the crest curve ,crest curves are applied when the change in grade is positive for example when ascending valleys while sag vertical curves are used when descending on planes and there is a negative change in grade.

Properties of vertical curves Regardless of whether it is a sag curve or a crest curve these curves have three points. These points are:PVC: this is also called the point of vertical curve. It represents the start point of the curve PVT : stands for the point of vertical tangency and is the endpoint of the curve PVI: stands for pint of vertical intersection Fig 1 showing the properties of vertical curves For equal tangent curves, half of the length of the curve is positioned before PVI and the other half after.

This forms a uniform curve