The impact of the availability function on the structure of unit costs in a construction project: a case study

Abstract

Neglecting availability during bidding and project execution can lead to inaccurate cost estimates and organizational problems. The significance of availability is essential in evaluating the duration of failures and repairs for both individual system components and the overall system. This assessment directly impacts project timelines and associated costs. This paper examines how the availability function influences construction production costs, particularly in highway construction, where mechanized work is highly represented. The proposed methodology evaluates how operational availability affects overall project availability and the capacities of construction system components, which are critical for accurately calculating unit costs in the bill of quantities. Past experiences indicate that project cost estimates and profit margin calculations—reflecting the difference between actual prices and projected costs—may lack precision. A system for producing and embedding bitumen-bonded materials for road pavements was selected to test this methodology using real-world data. Specifically, the data used to calculate unit costs, including machine downtime costs and durations, were compared with actual conditions during the construction of a key pavement layer in road projects. The results show that actual unit costs, which incorporate the availability factor, are 10.57% higher than those obtained using the traditional approach. This underscores the risk of losing projected profits and suggests that contracted prices may be underestimated, potentially leading to significant financial losses for construction companies.