Life Cycle Cost Analysis of a Bus Structure

The importance of light weight materials are increasing especially for transporting applications as different types of vehicles. Though, the cost for production may increase due to higher material cost this can be beneficial in other parts of the product life cycle, especially the operation phase. By using light weight materials the structural weight decreases, which can be utilized either as reduced fuel consumption, increased payload, increased speed or increased range. This have been demonstrated in a number of projects especially concerning ship structures were both life cycle cost and environmental analysis has shown the benefits with light weight materials in composite sandwich structures and aluminium structures. In this study a bus structure originally manufactured in steel is investigated. The new lightweight structure is produced in sandwich technique with face in glass fibre polyester and different core materials, PET, PVC and PS depending on location in the structure. Life cycle cost analysis, LCCA, has been made to compare the steel structure with the sandwich structure. Included phases of the life cycle are production, operation and disposal. The result from the analysis results in a decrease of life cycle cost by 3 to 4% depending on the fuel price and the fuel consumption. The production cost for the sandwich structure is slightly higher, 4%, than the steel structure. This is explained by the higher material costs for the sandwich structure. By identifying the break-even point it is clearly shown that a decrease by two year, from year 4,5 to 6,5, is the result when doubling the fuel price, 1 €/litre to 2 €/litre. This is explained by the weight decrease of 5% for the total weight giving lower fuel consumption for the light weight structure by 5%.