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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

LIFECYCLE COSTS AND GROUND SETTLEMENT RISKS IN THE SELECTION OF FOUNDING METHOD OF THE ROAD EMBANKMENT

ELINKAARIKUSTANNUKSET JA PAINUMARISKIT TIEN PERUSTAMISTAVAN VALINNASSA

Ground improvement costs make up a large portion of the total lifecycle costs of the entire road. Until this time these costs were not systematically taken into account when choosing the final ground improvement method. The aim of this study was to find out how counting of the lifecycle costs of the different ground construction methods could be developed, so that the total lifecycle costs of the road would be minimized for both the road keeper as well as the road users. At the beginning of this study there is a review of the most important factors that affect both the lifecycle costs and the accounting of those costs for the chosen ground improvement method. The aim was to introduce the techniques of the lifecycle counting as well as the problems and assumptions that are associated with these methods. These issues have to addressed before lifecycle costs can be calculated. Also the most important risks with ground construction and the ways to deal those risks in different contract forms are presented here. The latter part of this study deals with the lifecycle calculations of the different ground improvement methods. Calculations were drawn up based on the ground conditions under the chosen soft clay area, on top of which the road embankment was to be founded. Ground improvement alternatives included preloading, lightweight filling materials, vertical drains, stabilization columns, soil replacement and embankment piling. Calculations were made by first engineering the structure according to the rules and regulations that are in use at the moment. The second phase was to calculate costs for the road keeper and the road user based on the engineered structure. In the examples the ground settlement risks and the consequences of those risks were taken into account. The amounts of risks were estimated based on the probabilities of the different ground settlement forecasts and repair costs linked to those forecasts. In this study investment costs and the lifecycle costs based of different decision criterions were compared. These criterions included expected lifecycle costs, lifecycle costs of the most likely and the biggest settlement forecasts. Calculations show that mere investment costs do not optimise the whole lifecycle costs. It is also shown that settlement risks should be taken into account when calculating lifecycle costs as this creates new dimensions to look the situation. Consequently the final decision may change completely. Many assumptions affect the results of the lifecycle cost calculations. Thus it is equally important to know the made assumptions, as it is to compare the final results. If the assumptions used in the calculations are not the same between to different sets of calculations then these calculations are not comparable to each other. Thus clear instructions how to conduct lifecycle cost analysis is crucial, if lifecycle costs are to be used as a part contract and tendering process.

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  • Corporate Authors:

    Finnish Road Administration

    Opastinsilta 12 A, P.O. Box 33
    Helsinki,   Finland  FI-00520
  • Authors:
    • JUNTUNEN, P
  • Publication Date: 2004

Language

  • Finnish

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00984495
  • Record Type: Publication
  • Source Agency: VTT Technical Research Centre of Finland
  • ISBN: 951-803-251-3
  • Files: ITRD
  • Created Date: Jan 7 2005 12:00AM