An Earthworks Energy Model for Practical use in Road Construction
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
With growing concern for rising fuel prices, peak oil, global warming and climate change in the last few decades, efforts have been made to address and alleviate the possible problems resulting from these threats. Within the transport sector these efforts have been made largely with respect to fuel efficiency of vehicles and alternative fuels. However one aspect not addressed to any great extent is the construction of the transportation infrastructure such as roads and railroads although it is known that this process consumes a lot of energy and causes emissions of greenhouse gases.The main idea behind this thesis is to formulate an energy model in order to assess energy use and greenhouse gas emissions in road construction projects. The scope of the thesis focuses on what is called the earthworks which includes the mass hauls, cutting, filling and crushing of materials. The process of forming the energy model was lead with the help of the following research questions:RQ 1: How can earthworks be optimized in a road construction project?RQ 2: How can energy consumption and greenhouse gas emissions of earthworks be assessed with the data available in the planning stage?RQ 3: What is the relationship between energy consumption and greenhouse gas emissions in road construction projects?The proposed energy model helps understanding the energy use in earthworks processes and is complemented with equations for calculating the corresponding energy use. Implementing the model in road projects requires a bill of mass quantities, a mass haul plan and a production plan. Knowledge about the location and project is helpful for further improving the accuracy of assessments when implementing the model.. In the model the energy use of earthworks is divided into three categories of machines or vehicles namely hauling vehicles, off-road mobile machines and crushing plants. Each category requires different methods for assessing their energy use.The application of the earthworks energy model is analyzed using a case study, based on two road projects in the city of Kiruna in Sweden. The source of crushed aggregates for the base course and subbase of the roads are compared. One alternative is to use nearby sources of gangue which is a by-product of the mining industry. This material can be crushed by a mobile crushing plant next to the road line. The other alternative is to buy these products from LKAB, the local mining corporation which also runs a stationary crushing plant located further away from the road projects. The first alternative will mean shorter mass hauls but might require its mobile crushing plant to run by a diesel electric generator instead of electricity from the grid. The latter issue turns out to be of crucial importance when the earthworks energy model is applied to the case study. In short, unless the energy source of the crushing of aggregates is electricity then the second alternative pays off even if the hauls are longer.One conclusion from the case study is that crushing of aggregates is a very energy consuming activity. Therefore it is an activity worth paying close attention to in order to improve the accuracy of its energy consumption. The fuel consumption of mass hauls is another aspect. It is not so well known how much the fuel consumption can differ between articulated haulers and trucks with trailers under given circumstances. They are designed for different types of conditions and hauling distances but there is an area where these uses overlap and within this area it is important to be able to establish which type of vehicle is the most energy efficient.The earthworks energy model is by no means complete. It is possible to expand it to involve more activities in road construction projects as well as increasing the detail. One way to increase the detailing in the energy evaluation is to connect it closer to the production planning and the implementation and use as a module in a planning software such as DynaRoad, which was used in the case study of this thesis. While increased detail and improved accuracy is important, what’s perhaps more important is to make the model more user friendly in order to spread its use to a wider audience.
Place, publisher, year, edition, pages
IdentifiersURN: urn:nbn:se:ltu:diva-55258Local ID: c248ca23-dc00-42df-8f9a-0046d9d338afOAI: oai:DiVA.org:ltu-55258DiVA: diva2:1028639
Subject / course
Student thesis, at least 30 credits
Validerat; 20130611 (ysko)2016-10-042016-10-04Bibliographically approved