The Civil Engineering project for the LHC is estimated at 350 MCHF, of which about 316 MCHF is for the construction contracts. These contracts are based on a system of remeasurement whereby the consultant estimates the quantities required for the construction of each structure and the contractor commits himself to the unit price, which define the initial tender price. There are many factors that affect the final price for these contracts, from increases or decreases in quantities of the estimated amounts in the original bill of quantities to variations to the contract. This paper will look at how these factors change costs at the individual level of a structure to the overall costs of the contract. It will look at how the Civil Engineering Group monitors these changes to calculate cash flows and final costs and how this information is used as a basis for budget forecasts