Auckland: Hamilton Highway Design - Case Study Example

Highway Design Table of Contents Introduction 3 Project Background Information 5 Site Condition of the proposed route for the highway. 6 Project Objectives 6 Projected Impacts associated with the construction of the road. 7 Encroachment on flora and Fauna. 7 Impacts on historical/Cultural Monuments 7 Destruction of aquatic life 8 Destruction of the Natural Aesthetics 8 Noise 8 Remedies to the impact resulting from the construction of the highway. 9 Methodology 9 Traffic Surveys 10 Investigation of Soil and Materials 10 Selection of the Route and Alignment 11 Pavement Design 12 Flexible Pavement Design 12 Conclusion 13 References 14 Auckland - Hamilton Highway design Introduction Auckland is a city that is located in the North Island of New Zealand. Auckland is the most populated area in New Zealand with a population exceeding 1.4 million people. The population of Auckland city is approximately 32 percent of the total population in New Zealand indicating that it is among the most populated cities in New Zealand. Auckland transportation sector is served by railways, roads, water, air and trams. Due to the growth of the motor vehicle industry, motor vehicle use have dominated the transport sector, and as a result, there has been the development of arterial roads and motorways which not only serves as motor vehicle transport ways but also, as dividing geographical features in the city. The city’s rapid growth has seen traffic congestion on the roads and this has resulted into time wastage thus hindering development activities. Hamilton is another city located in Waikato region in the North Island of New Zealand. The city has an estimated population of 150, 000 people, and this puts it in the group of most populous cities in New Zealand. The City has a diverse economy making its growth to be fast. The project highlights the construction of a road to link the city of Hamilton to the city of Auckland. This is an alternative coastal route linking the city of Auckland to the city of Hamilton. This paper describes construction of part of the highway connecting Muriwai beach to Raglan via Raglan harbour on the west coast of New Zealand. Muriwai beach is located in Auckland while Raglan harbour is located in Hamilton. The aims of the construction of the alternative coastal route are to give room for the expanding cities of Auckland and Hamilton and to ease traffic congestion on the existing roads. Below is a map showing the location of Auckland and Hamilton with the current existing road networks. Figure 1; Hamilton from Auckland (Google maps 2014) Below is a soil profile between the city of Hamilton and Auckland Figure 2; Soil Profile between the City of Auckland and the Hamilton City. (Google Earth) Various cross sections along the route are shown below Figure 3: Cross section from Auckland to Manukao harbour Figure 4: Cross section along the bridge Cross section from Manukau Harbour to the port Project Background Information A highway refers to a major road construction with an aim of connecting two or more places. When various highways interconnect together they form a network of roads referred to as a highway network or a highway system. Highway system in a given country encompasses all the highways in the country. This implies that each country has its own highway system. Each of the highways in a given country is named using predefined naming system basing on the type of the highway. A major highway, in most countries, used in connecting various cities or town centres encompasses various features that are aimed to increase the efficiency of the highway, enhance the capacity of the road and to minimize accidents to vehicles on the highway. This enhancement features include incorporation of dual carriage ways, use of grade separated junctions to connect the highway to other highways and other modes of transport, and other access features aimed at increasing the efficiency of the highway. Properly designed highway system is attributed to economic growth of any given town centre or cities the highway serves. This is due the fact that there is increased travel opportunities for either trading or pleasure. Moreover, trades routes to facilitate movement of goods are opened. Site Condition of the proposed route for the highway. Climatic conditions along the highway route has a significant influence on the construction methods used in constructing the proposed highway. The climate along the route onto which the highway is to be constructed varies, though at smaller margins. The summer in the area is characterized by relative hot conditions with maximum temperature ranging between 20 degrees Celsius – 30 degrees Celsius. Project Objectives The construction of the highway linking Auckland and Hamilton has main objectives of catering for the future growth of the two cities and also, to ease traffic congestions in the cities. The route of the highway is expected to pass through various sensitive areas such as Piha beach, Bethels beach and the Waitakere ranges, therefore, care is taken to prevent the occurrence of negative impacts resulting from the construction of the road to these sensitive areas. Thus to be able to devise ways of implementing the project with minimum or no destruction to the sensitive areas along the route, an environmental impact assessment along the route is necessary. The Environmental impact assessment is done to make sure the construction of the road conforms to the standards set by the New Zealand’s Environmental management authority and all other related management authorities. Projected Impacts associated with the construction of the road. The highway to be constructed is an alternative highway. This implies that the construction of the highway may involve excavation of virgin lands. Thus, it’s of at most importance to consider the various impacts that are expected to arise from the execution of the project. Below is a description of the various impacts associated with the construction of the project. Encroachment on flora and Fauna. The highway is expected to pass through sensitive places as earlier connoted. This means excavation to create a route for the highway is done. As a result, animal habitat is destroyed together with pre-existing flora and fauna. Since the highway is expected to pass in Waitakere Ranges, then there is an implication that there will be destruction done to the existing native forests during the construction process. Impacts on historical/Cultural Monuments The construction of the highway through the Piha beach communities and Bethels beach communities will have an adverse effect on the historical/cultural monuments in these locations. Moreover, the machinery used for the project will emit Carbon dioxide and carbon Monoxide gases which are acidic, and this destroys structures that are proximal to the highway. Moreover, the gases are released into the atmosphere, and as it is known, carbon dioxide is a recipe responsible for occurrence of global warming. Global warming has a negative impact on the environment. Destruction of aquatic life The construction of the highway will involve construction of two bridges at Manukau Harbour Entrance and across the Waikato River. The construction activities to create this structures has negative impacts on the water in these water bodies. This include pollution of the water bodies which negatively affects the aquatic life. Also, the re-routing of the river to facilitate the construction will destruct the normal habitat of the aquatic life. The construction of the piers and the foundation for the bridges profoundly affects the water quality. This due to factors such as increased soil erosion, wastewater pollution due to the construction process etc. Destruction of the Natural Aesthetics The process of the highway construction will involve excavation and cutting down of vegetation. This destroys the environment’s natural aesthetic. Moreover, the clearing of the vegetation result in the exposure of the soil to soil erosion agents thus resulting into soil erosion processes. Noise The heavy machinery used in the excavation and the construction process as a whole, results into production of disturbing sounds. Also, the vehicles produce vibration that are a nuisance to most people and some animals. These creates unfavourable conditions to people and other creatures living around this area. Vibrations are not only a nuisance, but they have negative impacts on the nearby creatures whereby they cause cracks and structure instability in general. Above are the major impacts associated with the execution of the project. For effective implementation of the project, this impacts should be eliminated, and in cases where they cannot be completely eliminated, they should be minimised to acceptable levels. There are remedies that can be implemented to reduce the effect of the above impacts. These remedies are as outlined below. Remedies to the impact resulting from the construction of the highway. i. Only the necessary vegetation should be cleared during the construction process to prevent overall destruction to the vegetation. ii. There should be cultural heritage protection plan to protect the cultural/historical regions mentioned above. iii. Treatment of wastewater resulting from the construction process should be done to acceptable standards iv. Use of noise suppressors on construction equipment to prevent excessive noise production. v. Construction of the highway across the Waitakere Ranges will have a great impact on the animal parks and the natural plants. Thus, the best alternative is to construct a road around the pack to prevent destruction to the environment. Details of how the road is constructed along the Waitakere ranges are discussed in the later parts of the paper. Methodology The process of the highway constructions includes various inventory studies, surveys and investigation in preparation for the actual road construction process. All of these entails traffic surveys, sample collection from pits along the proposed alignment, borrow area identification to facilitate construction of such things as bridges, sample collection, among others, surveying in detail along the highway alignment, hydrological study for the draining structures such as culverts, and finally, investigation of pre-existing roads. Traffic Surveys The traffic survey is aimed at studying and estimating the amount of traffic that is likely to use the highway. This is vital since it is paramount during the planning stage and design stage of the project execution. Also, it helps in determination of financing options. To obtain the annual daily traffic at designated points on the highway alignment, the average daily traffic is multiplied by the seasonal correction factor. Furthermore, using the collected traffic data, a vehicle damage factor is determined. Investigation of Soil and Materials Material and soil investigation are paramount in the determination of the properties of the sub grade. This process entails the collection of samples along the alignment. In the sample collection, pits are dug on the natural ground to be able to determine the carriageway soil strength and collect samples for lab tests. These lab tests include; i. Determination of Atterberg limits ii. Analysis of the grain size iii. Determination of maximum dry density iv. Determination of the optimum moisture content v. California Bearing ration determination (CBR Tests) vi. Determination of swell index Carrying out the above stated tests is paramount since it’s facilitates determination of various soil properties that are vital in the planning and design of the highway. Selection of the Route and Alignment There are various factors to be considered in the selection of the route and alignment of the highway. The most important factors considered include physical features along the proposed route and the relationship between the features and the geometry design. Some of the physical features affecting highway route selection and alignment include soil conditions, topography and the current land use. In summary, the route selection and alignment of the highway entails reviewing of the topographic maps, geologic maps, and the environment impacts that will result from the process. In the route selection, conditions facilitating sudden changes in the highway alignment are avoided at all costs. Considering the above stated factors, the selected route that connects Muriwai Beach to Raglan by Raglan Harbour is as shown the map below. Pavement Design There are various types of pavements that are used in construction of a highway. The choice of a given type of pavement is dependent on various factors. Considering the various factors such as the traffic count, commercial vehicle count, environmental condition among others, a preliminary pavement design can be done. The preliminary pavement design caters for both rigid designs and flexible designs. The selection and design are based on TNZ/2 standards. This paper describes the design of a flexible pavement. Flexible Pavement Design Below is a schematic of the design of the flexible pavement. The proposed final highway is as shown in the diagram below The flexible layer to be designed has got various layers with measurements as indicated in the diagram below. Conclusion The proposed highway design is tricky. This is due to the fact that the high way has to pass through sensitive areas as connoted in the paper. This calls for implementation of special measures counter the negative effects associated with the construction of the highway. References Gibbons, J. (1999). Pavements and Surface Materials. Kühn, W. (2013). Fundamentals of Road Design. Southampton: WIT Press. Schonfeld, P., & Jong, J.-C. (2006). Intelligent Road Design. Billerica: WIT Press. Schoon, J. G. (2000). Geometric Design Projects for Highways: An Introduction. New York: ASCE Publications. Transit new Zealand. (2005). TNZ B/02:2005-SPECIFICATION FOR CONSTRUCTION OF UNBOUND . Yoder, E. J., & Witczak, M. W. (1975). Principles of Pavement Design. New York: John Wiley & Sons. Read More