Highway Civil Engineering - Research Paper Example

The proposed west coast highway connection between Muriwai Beach and Raglan on the North Island of New Zealand Highway Civil Engineering Institution: ID Number: Table of Contents Table of Contents 2 8.0.Vertical Alignment 12 Tangent Grades 13 1.0. Introduction The study of civil engineering in often cases introduces students to several aspects of learning, one of which is the concept of highway engineering. With a likely regard of it as a branch of civil engineering, highway engineering may be categorised into the most important stages of planning, design, building and the preservation of highway roads and bridges, as well as tunnels. The sole purpose for engaging in the same is that it allows for the enhancement of efficacy and safety in the transportation process of people and goods from one place to another. In this regard, it is imperative that at all times, the engineers who are largely involved in the design and development of highways ensure that the consideration for the flow of traffic in the chosen routes and the other issues such as the designing of interchanges, intersections and the highways in themselves are done with precision. Subsequently, in the development of highways, aspects such as the geometric alignments of the roads, the construction materials that have been used in building the highway pavements and the pavement’s structural schemes should be taken into consideration (Singh & Goel, 2011). Besides these, the highway engineers are also concerned with the maintenance of the built roads, as well as the thickness of the same. When designing a highway pavement, it is also important that the engineers consider other more significant factors such as the anticipated volume of the traffic that will use the road network to be built, particularly during its design and development phases so as to enable proper engagement of all the construction aspects. The essence of the predictions or determinations of the traffic volume are so that the highway engineers are enabled on the best means possible to construct the highways and develop the highway systems. Additionally, it is essential that the traffic volume for the road’s future use be determined owing to the fact that traffic usually subjects the pavements to constant and persistent wear and damage. Engineers and design team for the road network need to consider that the wear and tear amount experienced on a road network is defined by the quantity of automobiles that use it and the specific weights (in tons) of the vehicles, as determined over a given time period. However, it is also essential that the engineers take into consideration the joint issues such as those related to the effect the highway project may have on the environment. For instance, matters such as pollution in the forms of air pollution, noise, water and land pollution should be looked into before the commencing of a project. Consequently, the ethical codes demand that other ecological influence that the development may have on the local or surrounding communities, especially in relation to issues of displacement and disruption of livelihoods and property, need to be assessed first. In order to be achieve the above mentioned aspects, it is required that the project’s design team together with the highway engineers are advised to accurately assess and evaluate the best and feasible route that a new road network should follow. This is significant to the sense that it would greatly encourage developmental activities such as the growth of urban centers in the regions and facilitate the identification of the likely geotechnical challenges that might be experienced; thus, save the team time and resources from being wasted. The main concept in this is that the design team averts any external and internal factors that might impact on the project’s viability. For instance, Gibbons (1999) further acknowledges that estimation of the damage to the pavements can be determined through the axle loads of the automobiles that are expected to use the road within a given time period (expected lifetime). However, all these aspects solely depend on the determination of the nature of the soil aggregate that a road or pavement is to be built on, which is a key requirement in civil engineering to be considered by the highway engineers. In this line, it is required that the following essential aspects are provided for in a road assessment report by the design team comprising of highway engineers. Information in relation to the road site’s stability. The stratigraphy of the site or the typical subsurface conditions that is likely to be encountered during the investigation. Aforementioned valuations of the site’s liquefaction potentiality, as a result, of the seismic conditions that may be encountered on the proposed route. The preliminary recommendations associated to the earthworks, site’s infrastructure and the foundation taking into deliberation the expected geotechnical constraints. The viable prospects on the selected route’s suitability in terms of geotechnical features. As a result of the aforementioned geometrical and geotechnical aspects, this technical report basing on the recommendations and conclusions that shall be made shall strive to provide a guide into the feasibility means by which the project can be attained. To achieve this, this study shall be based on the published geographical maps that shall be obtained from Google maps and in the website of Auckland Council. Subsequently, reference shall be made to the formerly completed projects of a similar manner and the experiences that were gained by their design teams in their conducting. Finally, the report shall consider the historical geotechnical investigations that have been conducted along the route but, to a limited degree in the determination of the project’s aspects such as the soil laboratory tests appropriate for the construction, the cone penetrometers and the means of drilling the machine boreholes (Harrison et al., 2000). The study recommends that these tests be analysed given that they are likely to form part of the proposed route’s resourceful guides in the implementation and construction stages. Subsequently, the test results obtained will be adequately used in redefining, refining and ascertaining the probable conclusions of this project as shall be presented in the report. This will be detailed for purposes of consenting and planning of the proposed highway routes along the respective beaches. 2.0. Background This proposed project seeks to provide an in-depth study into the efficacy of the alternative coastal highway network that has been proposed to pass through the west coastal regions of Auckland; thus, linking the city with Hamilton. The investigation seeks to provide an option by which future growth in the two cities shall be heightened without needing to show apprehension about the problem of traffic congestion since, the proposed route would aid in the alleviation of the traffic congestion in both the cities’ centers. Subsequently, this report is essential given that it seeks to provide for route analysis into certain sensitive neighbourhoods such as the Waitakere Ranges, Muriwai Beach and the Raglan Harbour considering the environmental sensitivity of the regions to the communities around. In addition to this, the proposed route shall take into consideration the views of communities in other areas along the route such as in Bethells and Pilha beaches so as not to have the project adversely affecting the lives of the people living in the areas. In this, the study recommends the conducting of the consultations in a much careful and crucial manner owing to the livelihoods involved. Accordingly, the proposed project shall take into consideration the Oaia Road route that shall start from Muriwai Beach and comprise of two major bridge structures to be built at the Manukau Harbour entrance and the Waikato River (Port Waikato). Both of these structures shall be expected to be premeditated and constructed in a manner that shall allow for the passage of ships under them. Ultimately, it is expected that the proposed highway routes shall end at Raglan but, without the necessity of having to cross the entrance of Raglan Harbour. However, the report shall provide for a clause stating or recommending the need for the connection of the proposed route to the State Highway network that is currently in existence. This shall be supported with justification as to the choice made on the highway’s termination point. 3.0. Rationale for the project This project is being conducted taking into consideration several pertinent matters that are significant to its successful adoption and completion. First, is the anticipated highway distance that is approximated based on the air measurements, to be 114.42 km. However, on the ground, the distance is proposed to be about 116 kilometers between the cities of Auckland and Hamilton. In this manner, the proposed design considers that the most viable and identifiable route that would connect Muriwai and Raglan and still allow for future expansions is the most effective one; thus, would greatly benefit the local communities. Subsequently, the choice for the 116 km route is based on the fact that it would greatly allow for the preservation of the cultural and environmental heritages of the communities on its path. As such, this report finds the proposed route from its starting point to the end to be the most feasible for the achievement of the road network construction. Based on a contoured map, the distance is as shown in the figure below. Source: Google map On a straight line, the distance of the highway from the starting point to the termination point is as presented by the red dotted line on the map above. However, the green line represents the true proposed passage for the highway considering the terrain of the coastal region. However, there are certain anticipated challenges that shall be faced in the design and enactment of the highway project such as in relation to the upholding of the desired outcomes of the respective communities. This is because the communities would in a sense appear to be influenced politically to hold dissenting opinions regarding the effect of the project on their heritage and environmental sustainability (Essex, 2007). Ultimately, the attainment of this project shall not be successful without the incorporation of the aspects of design and construction of highways as detailed in the Unitary Council Plan of Auckland city; thus, ensuring that it is incorporated into its development plans for the future. 3.0.1. Selection of the site The area for the proposed project extends to the southern urban areas and beyond the arterial route; thus, necessitating the investigation area to be outspread to the west from the existing township. The site’s topography is expected to vary a lot with instances of typical ground elevations in the route’s centre at its low lying coastal flood plains. The highway shall also pass around the Red Hills area that is situated to the south east of the city and bound by the SH16 to the north and North Auckland to the west. Topographically, the area for the proposed project as variations that are characterised by elevations ranging from 50m RL to 100m RL as it gets more steeply inclined. The total coverage area for the project is approximated to be 2,200 ha with a topographical elevation that ranges from 25m RL to 40m RL. However, the southern region steeps towards the top stream catchment area and encompasses the highest elevations that range from between 50m RL to 100m RL, as highlighted above. 4.0. Aim and Objectives The main focus of this project shall be on the determination of the most feasible route that can be adopted in the construction of a highway from Auckland to Hamilton passing through the coastal towns of Muriwai and Raglan. This shall be supplemented by the following specific objectives. To determine the project’s route through the review of the published geographical maps of the area. To review the geotechnical database of the region and the generic appraisals of previous geotechnical investigations, and their impact on the current project. To review and provide justification for the geotechnical investigation data that shall be supplied by Auckland Council’s website. To assess the prepared geological maps of the coastal region to show the extents for the type of soils situated along the proposed highway route. Based on the aims, the report files the areas of interest as those shown in the geotechnical maps in Appendix A figures 1 – 3. 5.0. Methodology This study shall use a descriptive research design methodology that shall entail the collection of information from relevant sources such as books, journals and magazines in geology and geotechnical subjects. The obtained data shall be subjected to analysis using appropriate techniques so as to enable the making of inferences. Primary data will not be sourced at all, and when done, it would be to specific key informants knowledgeable on the area’s topography, and whose information shall only be used to supplement the already obtained secondary data (Lindeburg, 2012). 6.0. Route Alignment Selection Discussion 6.0.1. Geological Challenges A description into the geological units across the entire project region is as presented in the figures in Appendix B. according to Bieniawski (1989), the Q1 labeled areas in terms of soil topography comprises of the alluvial soils of the Tauranga Group Holocene while the areas labeled Pup comprise of Tauranga Group Puketoka or Pleistocene Age soil formations. Omm refers to Muharangi Granite rocks while other areas grouped within Bethells to Raglan consist of Puriri Mudtsone, Hukerenui Mudstone and Whangai Formation. Figures 4-13 in Appendix A shows a comprehensive illustration of the geology of the route. 6.0.2. Geological Units Considering the soil profiles listed above, it is evident that the highly compressible organic clays and silts that range from soft to firm textures are Holocene alluvial soils. This type of material borders rivers and streams as well as gully features and along low lying coastal areas. It also contains layers of peat and low strength or compressible soils considered unsuitable for construction works. Thus, it is indispensable that the Holocene age alluvial soils be removed first at the earthwork construction processes, referred to as the sub-divisional and backfilling earthworks. However, during the process, the important and environmentally sensitive features in the area such as watercourses should be protected and retained during the engineered fill. The Pleistocene published in the geological maps shows that some areas are positioned on stumpy relief regions lain beneath by the Puketoka Formation alluvial soils of Tauranga Group (pup). Identifying this type of soil would focus on the light grey to orange brown pumiceous colour of the soil in the nature of sand, silt and gravel. The gravel comprises of muddy black lignite and peak that are compressible. The Puketoka Formation soils peat layers could be approximately 3m thick and present within upper 10m. The peat contains amorphous fibrous content subject to pre-consolidation. This limits settlement under moderate loading but when pre-consolidation pressure limits are exceeded, primary consolidation rates of the peat becomes high. On the other hand, peat soils take a long time after construction to consolidate due to secondary consolidation effects. Given that the route shall pass through the coastal area, the loose medium layers of the upper Pukeoka formation soils shall be underlain by dense sand underlying the silty clays. The layers found shall vary considerably in depth and shall range from 10-20cm. According to Hudson & Harrison (2005), the layers shall not be continuous given that the upper layers shall be limited to a thickness of 3-5m; thus, making the soil to be susceptible to liquefaction due to seismic actions. In the east coast bay, formations of the Miocene soil shall be found, which shall contain sandstone and mudstone layers together. This shall be coarse grained, more volcanic and comprise of weak conglomerates and sandstones. The residual soils from weathered parent rock increase in strength with depth with a thickness varying between 2-10m. This group of soil display engineering characteristics for earthworks construction such as stable slopes at 35-400, very steep and stable slopes cut angles, and retaining of embankments with possibilities successful completion. Geotechnical properties for the soils include low compressibility, rapid consolidation rates, high effective stress shear strength parameters and high residual strength. 7.0. Stratigraphy This discussion shall rely on limited geotechnical investigations taken for other purposes within the proposed route and published geology (Edgerton. (Ed.), 2008). Due to the limited data and the large size of the area of interest, actual conditions may vary from those presented below. Muriwai- Bethells: This area has predominantly Puketoka Formation overlying the east coast bays formation and Cornwallis formation rock. Pilha- Raglan: This area has Tauranga Group Alluviu but low ling valleys and gullies with Northland Allochthon Rock (Fookes, 1997). Bethells-Pilha: This area is composed of residual Waitemata Group soils overlying Pakiri Formation Rock with rare areas containing undifferentiated Northland Allochthon. 8.0. Vertical Alignment This shall be made up of tangent grades or straight lines in the vertical plane and vertical curves. It is documented in the profile of the area. The profile is defined as a graph with elevation at its vertical axis and distance and measured in stations along the established centre line or horizontal reference line that acts as it horizontal axis. Tangent Grades These are the graded designated according to their slopes or grades. The maximum grades vary and depend on the type of facility and as no absolute standard. Steep grades slow down heavy vehicles increasing operating cost (Price & De, 2008). The degree to which vehicles are slowed depends on the steepness and the length of the grade. This is achieved through traffic analysis other than simple geometric design. Since the highway passes rural areas, the recommended standards for maximum grades are level (3-5%), rolling grade (5-6%), and mountainous grades (5-8%). 9.0. Conclusions The design for the Muriwai Beach to Raglan defines a highway design that shall provide for satisfactory conveyance services to allow for future expansion of the highway. The inquiries that have been done on geotechnical and geology of the area define geotechnical suitability and constrictions that are likely to be met during project delivery phase. There is a minor alteration, nonetheless, in the geological conditions presented in the route with those conditions that have been outlined in the expected areas, particularly in the geological boundaries; thus, requiring identification by particular investigation. In identifying the geotechnical hazards that pose potential constraints to the development of the route, the study highlights slope instability, liquefaction, and soil compressibility, as the core constraints. Development constraints are; earthworks, civil infrastructure, and individual property development. Nevertheless, these geotechnical hazards and development constrictions that have been presented shall have no effect on the future expansion of the proposed route. 10.0. List of Appendices and Tables Appendix A Table 1 – Spectral Shape Factors for seismic subsoil class Site Seismic subsoil Class Class B – Rock Class C – Shallow Soil Class D – Deep/soft Soil Spectral Shape Factor 1.0 1.33 1.12 Table 2 – Assessed Peak Ground accelerations for varying Site Subsoil Class Seismic Case Class B – Rock Class C – Shallow Soil Class D – Deep/soft Soil Serviceability Limit State Event (1 in 25 years) 0.032g 0.042g 0.04g Ultimate Limit State Event (1 in 500 years) 0.13g 0.17g 0.15g Table 3 - Slope Instability Potential: Slope Profile Limits Geological unit Slope Instability Potential - Slope Profile Limits* Low Medium High Holocene Alluvium 0-10 o 10-23o >23o Puketoka Formation/Undifferentiated Tauranga Group 0-10 o 10-23o >23o Waitemata Group (includes ECBF, Cornwallis Formation, Albany Conglomerate and Pakiri Formation residual soils). 0-15o 15-26o >26o Undifferentiated Northland Allochthon 0-8 o 8-18 o >18 o Table 4 - Summary of Predominant Soil Compressibility and Building Settlement Potential Hazard Kumeu-Whenuapai (Refer to Figure 27 in Appendix A for details). Area Kumeu Huapai Future Business Brigham Creek Red Hills North Red Hills Scott Point Riverhead Greenfield Investigation Areas Low X X X Medium X X X X X X X X High X X X X Geotechnical Desk Study North and North-West Auckland Rural Urban Boundary Project Auckland Council T&T Ref. 29129.001 August 2013 Warkworth (Refer to Figure 28 in Appendix A for details). Area Warkworth North and East Warkworth Warkworth South Hepburn Creek Future Business Low X X X X X Medium High Silverdale (Refer to Figure 29 in Appendix A for details). Area Wainui East Silverdale West Business Silverdale West Dairy Flat Okura/Weiti Low X X X X X Medium X X X X High References Edgerton, W. W. (Ed.). (2008). Recommended Contract Practices for Underground Construction. SME. Essex, R. J. (2007). Geotechnical Baseline Reports for Construction: Suggested Guidelines. ASCE Publications. Harrison, J. P., Hudson, J. A., & Hudson, J. A. (2000). Engineering rock mechanics: Part 2. Oxford: Pergamon. Hudson, J., & Harrison, J. P. (2005). Engineering rock mechanics: An introduction to the principles. Amsterdam: Pergamon. Lindeburg, M. R. (2012). Civil engineering reference manual for the PE Exam. Belmont, Calif: Professional Publications. Price, D. G., & De, F. M. H. (2008). Engineering geology: Principles and practice. Berlin: Springer. Singh, B., & Goel, R. K. (2011). Engineering rock mass classification: Tunneling, foundations, and landslides. Burlington, MA: Butterworth-Heinemann. Read More