CIVE1180 – Transport Engineering 1
The aim of this report is to create 5 alternative alignments for a given fixed point E-K-M in a topography map. It also aims to develop skills and knowledge of designing a road.
In the process of creating all the alternative alignments, Auto CAD Civil 2015 must be used. This needs a brief step by step way to clearly and properly design an alignment and show its specifications. The alignments’ specification involves a clearly labelled profile of the plan, slope, radius of the curve, length of the road, grades in profiles and mass haul.
The best route is then chosen base on the result of comparing all 5 alignments using the screening criteria. The criterion consists of length of the road, curve radius, travel time, maximum gradient, amount and difference of cut and fill. The alignment that comes out the greatest would then be further analysed using mathematical calculations for modification based on curve operating speed estimation.
Through a given topographic map, a road must be designed to suit the contours of the surface. Considering that the road will be of high speed, it is crucial to design a road that has a high curve radius and that the straight are not too long. It is identified that the route shall start at point E and finish at point M that is connected via point K. These points are then used to build 5 appropriate alignments that will then be tested for further designing and analysis. Safety concerns are also important in examining all the created alignments. Through the selection process it is also vital to examine the optimal speed and comfort. A constant operation speed throughout the road is essential as well as having a smooth transitioning into the road and exiting during construction planning.
5 alternative alignments must be presented to provide a number of valid routes that can be used to traverse through the topography. These alignments must all fulfill the necessary requirements at a satisfactory level based on the Austroads. These factors include the gradient throughout the road, length of the destination and the curvature. It is important that these factors are at an ideal level for the demand to be reached.
In the preliminary plans, it is vital to achieve a good geometric design that satisfies that requirements from the standards. This is to have the right balance between the levels of traffic services provided, safety, whole life costs; flexibility for future upgrading that would not cripple the economy and environmental impact as well as social impact.
The purpose of the project is to develop a road network that must follow the road design guidelines by Austroads. The designed Roadway will be starting from Point E, passing through point K and end up at point M. The geometric design of all components will be included in the project. Each member is required to develop a different route alternatives connecting point E, K and M using Auto CAD Civil 3D 2015. Each alignment will contain clear plans and profiles with clear labelling of length, radius of curves and grades in profile. These alignments will then be compared and examined clearly using the screening criteria in order to choose the best route alignment design. The best route will be chosen based on the level of satisfactory of the following criteria: Safety, Economically Efficient, Future Need, and Environmental Impact Mitigation. The best alignment will be further analysed for improvements. As traffic’s is on both directions, the estimation of operating speed is needed for opposite directions of travel. The modification of the design may be required based on the estimated operating speed.
There are some controls and conditions that need to be addressed in order to maintain a comfortable and safe roadway that is suitable to its intended use. The route passing through points E-K-M is designed according to the standards produced by AustRoads.
During the preliminary process, there are two main parameters that are required for consideration. This includes the design vehicle and the type of the road.
In the preliminary design it is imperative to consider the capabilities of the vehicles that will be in the roadway. Evaluating the types of vehicles can provide indication of the said capabilities. For this design, both heavy (trucks) and light (cars) vehicles will be considered. Some model vehicles will be used to make mathematical calculations of operating speeds and roadway geometries that includes the intersection layouts and lane widths.
The geometry design of the road is significantly affected by the physical and operating characteristics of the vehicles using the road. According to AustRoads section 2.2.5, there are four general classes of vehicles that have been selected for design purposes including: design prime mover and semi-trailer (19.0 m), design single unit truck/bus (12.5 m), service vehicle (8.8 m), and design car (5.0 m). The road passing through E-K-M will be designed as an outer urban freeway with the speed limit of 110km/h at point E which is applicable for both heavy and light vehicles.
The type of the road is considered in terms of three variables; grades, surface conditions and cross-section. The interpolation and interaction of these three variables provides three road types; high-speed roads, intermediate-speed roads and low-speed roads. Based on the topographical section of the preliminary design task, a non-forest and non-mountainous region means that it ideally targeted a high-speed road.
In the preliminary process, the best alignment will be designed as an outer urban freeway with the limited speed of 110 km/h which is classified as “outer urban freeway” according to Table 3.1 in AustRoads. Therefore, the road does not offer pedestrian, cycling, or frontage access. For horizontal geometry, the road is a combination of both straight and curves section. In order to minimize the variation in speed, the curves will be designed as a long curve with a large radius. For vertical geometry, the condition of the road along E-K-M is designed to be as flat as possible, with no ups and downs to minimize the environmental destruction during the construction process and also to provide the best comfort for the road users. The freeway connecting E-K-M will consist of two lanes, one in each direction. Each lane will have the width of 3.5m as general traffic lane widths to be used for all roads, according to table 4.3 in AustRoads. The Road Cross fall is designed to be -3%, and the left and right swath width is both 40m.
|ü Direct route from E to M
ü Negligible uphill
ü Suitable for all kind of Vehicle.
ü Less number of curve
|c Big difference in cut and fill volume.
c Length of straight is more than 1000 km
c Very Steep Curve
|ü Very Low Cut and Fill
ü Suitable for all kind of Vehicle.
ü Smooth curve
|c Too many Vertical Curve
c Big difference in cut and fill volume
|ü Difference in cut and fill volumes reasonably good.
ü Shorter distance
ü Minimum number of curve
ü Suitable for all kind of Vehicle.
ü Smooth curve
|c Highest amount of Cut and Fill
|ü Low difference between cut and Fill
ü Suitable for all kind of Vehicle.
ü Smooth curve
|c The amount of cut and fill is very high.
|ü Suitable for all kind of Vehicle.
ü Slope is higher than minimum
|c Difference between cut and fill is high
c Longest Distance to travel
c Longest Travel time
c Too many Vertical Curve
Table 5.6 Pros and Cons
- Curve Radius: The steepness of the curve depends on the curve radius. Larger curve radius is preferable to increase safety and reduce design speed variation as well as save travel time.
- Maximum Gradient/Uphill Travel: The vertical slope of the road, smaller slope is preferable.
- Length of the road: Shorter length is preferable to minimise cost and save travel time.
- Amount of Cut and Fill: The amount needs to be minimised to reduce costs.
- Difference between Cut and fill: The difference is to be as close as possible to reduce costs.
- Travel time: The travel time can be estimated from the length of the road and steepness of the curve.
- Provision for cyclist and pedestrian: is minimum for all routes, as the highway does not provide.
- The environmental impact is minimum because there is no forest or Aboriginal area on the map. There is no bridge or tunnel needed along the route that can impact the environment.
For the connection points E-K-M, alignment 3 provided the best solution for the design of the road. It satisfies greatly above the other alignments due to it providing the best in social, safety, and environmental aspects of the design and at the same time did great for economic reasons.
As the grades of the infrastructure being consistent as well as the curve radius of the road being as large as possible ensures that alignment 3 provides the safest preferable characteristics when it comes to safety segments. It also complies with the curvilinear nature as an ideal pattern that is actually aimed for at this plan. This includes all the blind spots for the driver’s line of sight that is obscured by the crests on the road profile. As the grades of the road are continuous and consistent, the infrastructure achieved a smooth slope which means that there will be a reduction in accident frequencies due to unexpected change on the road. The high valued curvature of the road also ensures an increase in safety. This is due to having a less amount of speed variations leading to achieving high speeds safely that decreases casualties that may occur and increases the efficiency on the road.
It also resulted greatly for economic reasons where the amount of cut and fill is almost equal and remained to be minimal. Having a small number of cut and fill decreases expenditure on resources needed to make the road even. This allows the resources from the external resources to be allocated to other important factors in the project that could lead to acquiring an optimum quality for the design.
The selected route also conforms to the design controls of the route. This involves decreasing the mass haul required and making straights as long as it can be. The road can function at its design operating speed by making straights as long as possible. The mass haul is also minimised for decreasing wear on engines which in turns provides as an advantage environmentally
For design alignment 3, there is no need for any additional complex infrastructures. This makes the route a viable solution and is the most suitable alignment in accordance with the given contours as it also acts natural with the surroundings.
This report aims to design a route that goes through 3 fixed points on a topographic map. To make an appropriate design, many engineering steps have been made to create a route for points E-K-M. This route presented many issues regarding the natural environment landscapes and the topography of the land. As a result, 5 alternative alignments were needed to be produced to iterate these issues. These 5 alignments were created and further analyzed based on various factors and specifications such as the nature of curvature, maximum gradient and etc. These factors were then weighed in to find the most suitable route that will undergo further designing and elaboration.
The road will be used by all sorts of vehicles however; cars and trucks will be taken into consideration in designing the route in all aspects. Since trucks are deemed more difficult to take into account based on the curvature and speeds, they were usually regarded within the radius of the road.
The 5 created alignments varied with respect to nature of curvature, radius of turns, straight distances, cut and fill consideration and overall length. In each alignment, the cut and fill was deducted to a minimum that led to the road aligning with the contours of the land that will result into a less haulage cost and more productive project.
Alignments were created using Auto CAD Civil 3D 2015. These routes provided a clear visual presentation of the roadway created with labeled profiles, grades of profiles, length of the road, radius of the curve and mass haul which is then compared to find the most suitable route for the project. After doing screening criteria, it was found that alignment 3 serves the best solution for designing a roadway in the topographic map.
The chosen route proved to satisfy all the necessary requirements in terms of safety, social, economic and environmental reasons as it ranked the best during the screening criteria. This alignment then undergoes further analysis and mathematical calculations for its modification. The operating speed estimation for this route is then found in each of the stations which provide a great deal of satisfactory speed in each of the curvature of the road.
As a result, alignment 3 serves to be the most viable option in this preliminary project
- Austroads 2010, Guide to Road Design Part 3: Geometric Design, Austroads Publications Online, Australia
- Moridpour, S 2015, CIVE1180 Transport Engineering 1 Tutorial Week 3, RMIT University, Australia, viewed 28 August 2015, https://lms.rmit.edu.au/bbcswebdav/pid-6535653-dt-content-rid-13792978_1/courses/CIVE1039_1550/Week%203%281%29.pdf
- Ramsay, E 2015, CIVE1180 Transport Engineering 1 Lecture Week 5, RMIT University, Australia, viewed 17 August 2015, https://lms.rmit.edu.au/bbcswebdav/pid-6574148-dt-content-rid-14016716_1/courses/CIVE1039_1550/Week%205%285%29.pdf
- Moridpour, S 2015, CIVE1180 Transport Engineering 1 Tutorial Week 5, RMIT University, Australia, viewed 21 August 2015, https://lms.rmit.edu.au/bbcswebdav/pid-6535693-dt-content-rid-13792997_1/courses/CIVE1039_1550/Week%205%283%29.pdf
- Ramsay, E 2015, CIVE1180 Transport Engineering 1 Lecture Week 6, RMIT University, Australia, viewed 24 August 2015, https://lms.rmit.edu.au/bbcswebdav/pid-6580145-dt-content-rid-14081411_1/courses/CIVE1039_1550/Week%206%283%29.pdf
- Moridpour, S 2015, CIVE1180 Transport Engineering 1 Tutorial Week 6, RMIT University, Australia, viewed 28 August 2015, https://lms.rmit.edu.au/bbcswebdav/pid-6535706-dt-content-rid-13793302_1/courses/CIVE1039_1550/Week%206%282%29.pdf