Report On Road Extension Assignment
1.0 Introduction of Road Extension Report
In the context of this essay, road extension has been designed for Palkin Developments Ltd. An outline structure of site investigation for designing the road extension has been provided to the client. Therefore, a proper site-specific investigation of the road extension has to be provided depending on the area of car parking. The pavement type, structure of the road, and materials used for constructing the road have been provided in this report in detail using academic resources. A suitable drainage solution is designed during road construction by addressing the presence of stormwater on the road. With the help of academic sources, the drainage solution has been provided to the client.
2.0 Main body
2.1 Procedure for site investigation
For designing and constructing the proposed road extension an outline structure has to be done properly.
Location setting: First of all, the location of the road extension has been properly identified. The design and construction of the road have been done to connect with the car parking at the end of the buildings. Based on the design of the existing road, Woodcock Dale road the extension has been designed. The need for the extended road is depended on the car parking facilities for future local residents (Ziakopoulos and Yannis, 2020). The alignment of the road has been set up with a maximum transportation facility and with low construction cost.
Reconnaissance survey: This survey has been done to collect details about the obstruction along the route where the road has to constructors. A map of the extended road has been designed based on the geological factors of that area. In this site investigation process, the details about the building materials available in the locality have been gathered. With the help of a prismatic compass, Abney level this survey has been done. The angle of the slopes of the existing road and the orientation has been pointed out during this survey. For extending the road further the presence of trees, buildings, car parking areas, the number of cars that will be driven in the future, etc. has been investigated properly.
Development of data and map study: From the reconnaissance survey, the data has been gathered. During this survey, a map has been developed where the actual location of the extended road has been indicated (Meijer,et al. 2018). The length of the extended road, the length, and alignment of the existing road, quality of road surface, the volume of cars driven per day, load coming on the road, proper drainage system, slopes provided to the extended road, etc. have been provided in the map.
In-depth investigation: In-depth investigation has been done after gathering all the information related to the newly extended road. The length of the carriageway of the existing road and the speed of the cars were necessary to determine. In this stage, the characteristics of soil and the effect of storm water have been designed. Depending on the drainage system of the existing road a deep investigation has been done.
2.1.1 Measures required for the design
For designing and constructing the proposed road extension a lot of measurements were needed to consider by the site engineer. Due to make access to the flats and the proposed car park the road will be designed on the side of the building. It was required for designing the road in such a way so that it will have a pedestrian footway besides the building. Traffic volume, sight distance, alignment, grades, super elevation have been measured to design the road. The main components of the extended road such as cross slope, the width of the road, margins of the road, separators, curbs have been measured during the site investigation.
2.2 A brief desk study
In this brief desk study, a complete study has been provided regarding the reconnaissance survey and the risk assessment associated with the construction. Information has been gathered during the site investigation about the construction of the road (Henry,et al. 2018). Depending on the length between the car parking and the existing road, the length of the extended road has been decided.
2.3 Preliminary site investigation
Outline the details of the proposed road:
Mainly the road pavement structure is made of multiple layers of compacted materials. The layers have been provided with different thicknesses. Depending on the carloads coming on the road the thickness of layers has been provided. Since the road will be extended only for the private cars of that area, therefore the sub grades are provided properly.
Figure 1: Construction procedure of a road structure
Depending on the first condition that is when the existing road is sloping towards the train track, line of trees, and towards the proposed buildings shown in the given figure, permeable pavement design has been chosen. Actually, this type of pavement is made of a porous material that is able to flow the storm water to infiltrate through the pavement. This type of pavement is made of pervious concrete, paving stones, etc.
Based on the second given condition when the plate load test has been done and a CBR value of soil has been determined, therefore, a flexible type of road pavement has been chosen for the extension of the existing road.
Road structure is very important for designing a road maintaining the specifications. A road structure basically consists of the following components that have been determined from the preliminary survey. The foundation of the road is defined as sub-grade. It is one of the most important and the lowest part of the road structure. For this survey, it has been seen that the existing ground is slopping. Since the road is situated adjacent to the train tracks and towards the proposed buildings, in that case, the road structure will be designed very carefully. Clay sub grades are provided for this type of road structure when the road is subjected to the first condition. For the second condition, a stronger sub grade will be provided in the road structure.
Figure 2: Layers of road surface
Determination of road materials is a very important part of the construction of roads. Bituminous materials and cement concrete have been used as road material to construct the extended road based on the sloping of the ground (Sugianto, 2018). For the second condition, the road materials have been chosen that have the strength to perform as a construction material. The materials provided that can resist the materials under moisture and density conditions. In that case, specifically asphalt concrete, gravel, and sand compacted with a bituminous material have to be used to distribute the loads.
For constructing the extended road in the Harrow area, it is important to provide the values of each layer during the construction. Depending on the condition of the existing road the thickness of each layer has been decided. The first layer is the natural subgrade. The compacted subgrade is the second layer with a thickness of 150-300mm. After that subbase course is provided of thickness 100-300mm. 100-300mm thickness of base course is constructed. The thickness of the next layer that is the binder course is 50-100mm. At last surface course or the seal coat is provided of thickness 25-50mm.
Figure 3: Cross-section of flexible pavement
A research paper based on the road materials has been published by the researchers Jiang, et al. (2018). This research paper mainly focused on road materials that are environment-friendly. Along with that, the researchers stated that durability, structural stability, permeable properties, gas absorption, etc. properties are very important. In modern road construction the new pavement design principles, innovation of new road materials have been adopted widely. Along with modern civilization, and the development of road construction, road materials have been upgraded. Cement concrete and asphalt concrete are becoming the main types of high-graded road pavement.
Permeable asphalt concrete is a type of road material that has a porosity of 16% to 25%. For this type of road construction, basically, 2.36mm and 4.75mm sizes of aggregates have to be used (Jiang, et al. 2018). Different types of tests like the CBR test, rainfall intensity test, fatigue test, etc. have to be performed during the construction of roads. Due to long term use of the roads and with the continuous wheel loads of traffic pore-clogging and other problems can be happened. All the problems are related to shortening the life span of the roads. For tackling these types of problems the researchers have discussed a maintenance policy for the permeable asphalt road pavements to maintain the permeability of the roads.
An integrated road design and the analysis of road structure have been discussed in the research paper published by the researchers Tang, et al. (2020). In this research paper, the researchers have developed a framework that is necessary for the improvement of road construction. The problems developed during the road design can be resolved by implementing new informative technologies. For the design of the road pavement, proper inspection is needed. Based on the requirement of lanes the parametric design of the road structure has to be done. In the next step, the preparation of the base and sub-base layers has been done (Tang, et al. 2020). The thickness of the base and sub-base layer is the same and it is thicker than the asphalt layer.
Proposed road drainage solution:
During the design of this extended road, it is needed to address the presence of stormwater on the road. Based on the characteristics of the existing road, and the geographical condition of the Harrow area the new road will be designed.
The design of pavement has to be designed based on the surface drainage, the geometrics of the pavement, climate, type of soil, etc. First of all, a proper drainage design has to be designed based on the characteristics of the existing road. A road drainage solution consists of the following elements that are, outlet ditches, side ditches, inner and outer slopes, culverts, road structures, under drainage system, etc. The wearing course is the top layer of the road. Therefore, a waterproof covering has to be provided for protecting the lower structure. This course has to be designed in such a way that it can immediately remove the rain, waterfall from the road surface. Side ditches are provided to collect road water as there are many trees and train tracks. A rainwater ditch has to be designed to collect the rainwater from the roads and the surroundings. Based on the condition of the position of the extended road, under drainage has to be provided and for that, the road structure will be done that stay dry and that have a good bearing capacity.
Figure 4: Road drainage system
A proper road drainage system has been developed in the research paper published by the researchers Amatya, et al. (2021). According to the researchers' discharge of stormwater rate is very important. At first, a preliminary survey of soil and the characteristics of the existing road has to be determined. Determination of rate of flow of water and the possibility of seepage has been determined. For preventing the clogging of drains proper source of aggregates and the aggregates provided for the under drainage system have to be designed (Amatya, et al. 2021). At last, it has to be seen if the road design has the capacity to meet all the requirements based on the position of the area.
Figure 5: Components of road drainage system
2.4 Levels of road
The extended road will be at the same level as the existing road. The benchmark has been set up the same as the existing road that is at 45.750m above sea level. Depending on the thickness of layers the levels will have to be set up. A complete work procedure has been discussed here that will help the site engineers to determine the design based on the composition of the road materials. Excavation of earthwork has to be done depending on the planning and as per the requirements. Depending on the environment and the geographical condition the excavation will be done. The road will be extended to the car parking. The subgrade layer has to be tested before the excavation process. The excavation will be done based on the strength of the subsoil. For preventing the sub soil drainage under drainage system has to be provided and for that if there is any poor material that has to be removed.
During this construction procedure compaction is very important as many cars will use this road. A tack coat of bitumen has to be applied as per the load applied by the cars. After that, the mixed materials have to be placed as per the thickness of the layer. Subgrade, sub-base, base layers are provided and each layer has to be compacted and rolled very well. Rolling is done with the presence of water and the number of rolling is dependent on the thickness of each layer. Wearing or surface course is the last layer of the road construction that is directly exposed to the cars. The thickness of the bituminous surface for flexible pavement will be determined based on the existing road.
During this coursework, I have learned a lot about road construction as a project designer and a site engineer. For constructing or extending any road, a preliminary survey is required that helps to design the road. As a site engineer, this project helped me to determine the construction procedure based on an existing road. Depending on the condition of the existing ground and the cross falls on the road structure will be determined. I have also learned that it is very necessary to develop the tests regarding soil although the soil is proper for extending the road in the future. Road materials are very important that I have developed during the site inspection. Along with that for extending this road under drainage system has to be developed as beside the car park train track is also there.
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