Engineer's Estimates Shouldn't Be A Guessing Game

The occurrence of the Engineers Estimate far exceeding the submitted contractors bids, or worse ending up considerably less than those submitted, creates client/consultant tensions. In many instances these estimates are based on historical cost tables which are then factored up or down by a regional index to produce a unit cost for pipeline construction. This method becomes difficult to defend when the owner wants to know why the estimate was either too high or too low. Working jointly with the Sacramento Regional County Sanitation District (SRCSD) a costing model based on estimates of contractor production was developed to determine base construction costs for the $1,000,000,000 SRCSD Interceptor System Master Plan 2000 Capital Improvement Program. The costing model includes variables for labor, materials, and equipment. By inputting estimates for production rates, which vary based on soil type, type of development, depth of installation, method of construction, etc., the model calculates unit costs for pipeline construction. Although this does not guarantee flawless estimating for cost of construction, the basis for these costs are tied to specific assumptions, existing conditions, and anticipated contractor performance which may be easily explained and defended.