Road Pavement Design - Assignment Example

Name: Xxx Lecturer: Xxx Course: Xxx Title: Road Pavement Design Institution: Xxx ©2016 Table of Contents Road Design Summary 3 Introduction 4 Environmental Effect and Land Acquisition 4 Horizontal Alignment 6 Super elevation 8 Vertical Alignment 9 Assembly 10 Cross Sections 11 Earthworks 11 Drainage 13 Pavement Design 15 Equivalent Standard Axles (ESA) 15 Conclusion 18 References 19 Road Design Summary Length of road: 5 km Final bearing of road: N84° 28' 21"E Radii of circular curves used: 733 m CH of first horizontal TP: 0+100 Length of vertical curves used: No vertical curves Final gradient: 0.63% Earthworks volume: Total of cut volume - Total of fill volume - Maximum road reserve width: 60 m Total pavement depth: Introduction For time immemorial, the construction of highways is a very challenging affair due to the factors associated with it. However, advances in science and technology have introduced newer methods and techniques for the design and construction of Roads and Highways, to handle the ever complex designs being developed to adequately service traffic. The main aims of road design and construction are safety and cost- effectiveness. Different countries have their own design regulations which prescribe the procedures to be adhered to when designing roads. In Australia, ‘Ausroads’ are established for engineers to refer to as a guideline on pavement construction to meet the requirements for safety and cost. The rights of the population through which the road will pass will need to be respected, and the location of the road is selected so as to cause the least violation. The main properties to be considered for the layout of the road are the private farm lands and the industrial centre along Cobbledicks Ford Road (Wyndham Vale). The general terrain of the area for the construction of the proposed road is undulating, with no sudden changes in gradient, bar the Werribee River which crosses the proposed road. Environmental Effect and Land Acquisition Our day to day operation and activities could have an adverse effect on the environment. The use of infrastructure, such as roads, introduces numerous pollutants into the adjacent environments through gaseous fumes, trash from road users, and noise pollution among others. In this specific case, the proposed road crosses a river. This means that any pollutants from the road could very easily be introduced into the river’s ecosystem, resulting in the death or mutation of existing species. The road also passes close to farm properties, meaning that the pollution from the vehicles on the road could also result in poor crop growth, causing a reduction in the yield, thus less revenue for the farm owners. Indirect effects due to the construction of the road could be a change in the community structure due to the exposure of the local population to the lifestyles of the travelers. Due to the current development trend, road infrastructure is crucial to aid in the growth of the country’s economy. However, this growth should not cause the depletion of other sectors of irreplaceable value. The number of trees cut for road construction should be minimized and replanted to ensure there is no significant change in the micro- climate of the area. Figure 1: River pollution due to road construction in India[Vas15] Our highway design is proposed to be four lane divided two way road given that start point 100 meter from the intersection of Doherty’s Road Shannahans Road of Riddle Road and end point will be 300 meter south of Wyndham Vale along Cobbledicks Ford Road. The change of the area where the proposed road is to pass from the current land use to infrastructure development needs to adhere to the legislations in the area. It means that a land cannot be acquired unless land has been first set aside for a public purpose. So we have to keep in mind that all the rules and regulations while designing the roads must be checked, so we can complete the project without any disruption. In this area there is a Landfill and Recycling Centre, that the road to be built must pass by, so that, we have to keep in mind about what would be the effects of the road on this. And we need to do some arrangements while the construction of road for the safety of the private farms and Wyndham Vale industrial centre Figure 2: Satellite Image of study area[Goo161] Horizontal Alignment Figure 3: Horizontal alignment over contours from Civil 3D The start of the road coordinated at and was designed to be at to Doherty’s Road. The end of the road coordinated at and was designed to meet Cobbledicks Ford Road at. The proposed road alignment cuts the Werribee River at Horizontal alignment curve data and tables; Number Type Parameter Constraint Length Transition Length Table Radius 1 Line Two points 2.41km     2 Curve Radius 1.08km 2 Lane 733.000m 3 Line Two points 1.51km     Chord length(m) Chord Direction Pass Through Point1 m Pass Through Point2 m Start Direction     371113.3362,312674.2365 369957.5583,311640.6521   453.009 S30° 11' 42"W 69987.8477,311623.0269   S48° 11' 40"W     369957.5583,311640.6521 369673.0187,310324.0822   End Direction Mid-Ordinate External Tangent m External Secant m PI Included Angle degree           N84° 28' 21"E 35.874 238.160 37.720 144.0008           PI Station Start Point End Point   382224.4473m,323785.3476m 381233.5020m,322899.1593m 2+500.00m 381233.5020m,322899.2593m 370021.9284m,322535.4914m   370021.9284m,322535.4914m 370784.1298m,321435.1933m Centre Point m Attainment Method PI Point m       381734.8178,322364.1249 AASHTO 2001 Crowned Roadway 370068,322751.7632       Super elevation The maximum super elevation designed for the curved section of the road to allow for the design speed is. This implies a rise of the outer curve of the road of 3.5% (the 0.5% is added to overcome the camber present in the straight section of the road) and a fall of 3% of the inner curve of the road between the two transition points. The super elevation is not introduced immediately at the beginning of the curve, but at a distance before and after the curved section so that the maximum super elevation is achieved when the user gets to the curved section. If the transition for the super elevation were to start at the beginning of the curved section, vehicles would fly off the road as they entered the curved road section. Vertical Alignment The ground profile for the proposed alignment of the road is as shown below; Figure 4: Ground Profile from Google Earth The horizontal distance axis is separated into 500m intervals and the corresponding ground height at that position shown by the y- axis. The height value read off at each point on the chainage gives the accurate value if that height was measured on ground. The ground height of the start point of the road is at 71m and the end point is at 77m. The ends of the banks of the Werribee River (where there’s a sudden change in gradient) are at 61m and 59.5m on the left and right banks respectively. The proposed vertical profile of the road at the start point is at an elevation of 70m and it will follow a gradient of from the start point up to chainage at an elevation of 60m, where the bridge to cover the Werribee River will be constructed at zero gradient up to chainage . The road then climbs back towards the end point at a gradient of to give an elevation of 76m at the end point of the road. Since the topography is undulating for most part, no vertical curves are necessary so as to allow for the design speed of 110 km/hr. However, the change of gradient from solid ground to the bridge on either side should be smoothed so that there is no abrupt change which could cause discomfort for the users of the road. Assembly The design of the road pavement is symmetrical, being identical from the centreline to the guard rails on either side of the road. In the design provided, the outer extremities of our assembly design have no clear cut slope provided for drainage. This is due to the functionality of Basic Side Slope Cut Ditch in AutoCAD Civil 3D which requires you to specify the behaviour of the assembly in cut and fill situations. A slope of 4:1 was specified for the fill sections of the road to connect the proposed road level to the natural ground level, and as such, the guard rail should be provided for these sections. A ditch arrangement with a slope of 3:1 was specified for the cut sections of the road section. The general assembly from the centreline of the road cross- section was two 3.5m lanes bordered by a 3m basic sealed shoulder at the end, adjacent to a verge of 0.5m before the drainage for the road. The guard rail is erected at the end of the verge just before the road drainage. However, it is necessary to mention that the 4:1 fill gradient may not be necessarily achieved given the relatively smooth gradient of the area in question. Figure 5: Assembly Design Dimensions Cross Sections The cross sections for the road can be generated at any desired chainage showing the relevant cut and volume section areas. The volume that the specified cross- section covers can also be generated. Earthworks The volumes for the cut and fill sections of the whole road from CH 0+100 to CH 5+100 are as shown in the table below. These approximate volumes are calculated using Civil 3D and are in cubic metres. Table 1: Table for Cut and Fill Volume Table 2: Table for Cut and Fill Volume (Cont.) Total of cut volume - Total of fill volume - Drainage The drainage system of the highway is relatively straight forward due to the reason that there is a general slope downwards towards the river which is around the centre of the road. Hence a channel will be located in the median of the road, to act as a natural drainage whereby the rain water is caught and absorbed by the grass then naturally flows towards the river. In the case of a heavy flood or rainfall, pits and pipes will be installed at approximately 100m intervals on the horizontal alignment shown to catch the water and direct it to side drains located on both sides of the highway or one on either side depending on whether the area is cut/fill, so that water doesn’t build up within the median and flood back on the road surface. The side drains are also installed to catch the water running off the road .However the pipes and pits will be installed to lead the water towards the river. Figure 6: Horizontal Alignment showing positions of drainage pits Figure 7: Drainage Pit Design Pavement Design Design Parameters Design speed – 110 km/hr Design period – 25 years Annual Average Daily Traffic (AADT) – 9,000 pcu’s Direction Factor – 0.5 Lane distribution factor – 1 (from table below) Year – 365 days Table 3: Typical lane distribution factors[MEB12] Equivalent Standard Axles (ESA) The determination of ESA for the proposed road is dependent on the calculation of the average number of trucks using the highway per day. No. of trucks per day AADT – 9,000 pcu’s Design life – 25 years Assuming that 10% of the AADT is trucks - The equivalent standard axles are given by; Table 4: Cumulative Growth Factor Direction factor – 0.5 Growth rate – 3% Growth Factor – 36.95 For 1-way traffic, therefore; For an asphalt thickness of 200mm, the corresponding cemented thickness of crushed rock (CTCR) is 225mm. Figure 8: Pavement Design Chart[Aus12] The estimated prices per of asphalt and cemented thickness crushed rock are $1000 and $70 respectively. Both materials will be laid in place in three layers as shown below; Figure 9: Pavement Layers The breakdown of the pricing is as shown below; Asphalt 230mm – 3 layers CTRC 225 – 3 layers This gives a total cost of A thicker layer of asphalt provides a stronger pavement design which can withstand higher loads and is more durable. However, the cost of construction of such a pavement is significantly higher compared to a pavement with a thin layer of asphalt. Nonetheless, the main priority of an engineering project is to provide infrastructure that would be safe for the public to use without any wanton damage, and as such, the most suitable design must be chosen for the pavement. Conclusion The construction of roads and highways on lands that are otherwise occupied or have significant land use is a big challenge due to the costs associated with such projects. The horizontal alignment was chosen with the existing land use in mind, with the cost of changing it for road construction and the disruption to the environment being considered. The terrain across which the proposed road is to be constructed is relatively undulating with no sudden changes in gradient bar the Werribee River cutting across it. The terrain also facilitates the minimum requirement for side drains along a road to ensure the road would be sufficiently drained in the event of a flood or heavy storms. The data in this report was largely calculated with the help of engineering software, such as AutoCAD Civil 3D, and Google Earth. There was need for some manual input to give the software some direction. References Vas15: , (Vashishtha, 2015), Goo161: , (Google Maps, 2016), MEB12: , (MEB, 2012), Aus12: , (Austroads, 2012), Read More