Bills of quantities versus activity schedules for civil engineering projects

Bills of Quantities are the classical form of financial control used for pricing construction projects throughout much of the world. The New Engineering Contract, now published in its second edition as the Engineering and Construction Contract (ECC), has two main options for dealing with Priced Contracts: Option A adopting Activity Schedules and Option B using Bills of Quantities. It has been previously concluded that the use of Activity Schedules (option A) is preferable to the use of Bills of Quantities (option B) for the majority of engineering and construction work let under a priced contract with the NEC : ECC as the contract form. However, use of Bills of Quantities may be more appropriate for work in the building industry or for minor civil engineering work. The primary aim of this paper is to review these two systems, their relative strengths and weaknesses, and to make the case to the practitioner not conversant with Activity Schedules for their increased use in the appropriate contractual situations. The paper starts by examining some commonly held, but often false, assumptions about Bill of Quantities. It then reviews two models of how costs are built up for construction projects: the operational estimating model and an accountancy model. Following this, it examines three payment mechanisms for Priced Contracts: Conventional Bills of Quantities, Method Related Bills of Quantities and Activity Schedules. After outlining the possible advantages and disadvantages of each, the paper addresses the theoretical mis-matches between them, how costs are built up and how these result in problems in practice. The need for training for practitioners and organisations unfamiliar with the concept and detail of the new styles of contract is identified. The paper also summarises research findings of factors inputing in practice to the choice of type of contract form. It concludes that experience to date with the New Engineering Contract indicates that for civil engineering works, the use of Activity Schedules is normally preferable to remeasured Bills of Quantities. However, for minor civil engineering work, where the major risk is a small change in quantities, Bills of Quantities may be appropriate. For building work, providing it is actually fully designed and only minor changes are foreseen, Bills of Quantities again may be more appropriate.