A comparison of concrete quantities for highway bridge projects: preconstruction estimates vs onsite records

ABSTRACT

This paper compares onsite concrete quantities to preconstruction estimates for 18 highway bridges in Canada to quantify the differences in quantities and to identify the driving factors. Material estimates completed during planning and design play a crucial role in predicting project cost, duration, and embodied CO₂e emissions for construction projects. However, there is limited understanding of estimating material quantities for construction projects, and their impacts on other estimating processes, e.g., project cost, project schedule, embodied CO₂e assessments. Results show that 3–87% greater concrete quantities are used onsite compared to estimates, with the bridges’ substructures responsible for most of the discrepancy. The findings of this study inform our understanding of the preconstruction estimates and their interpretation. Adjusting for the discrepancy between estimates and onsite measurements as well as targeting the drivers of unexpected material use has the potential to reduce environmental impacts, minimize cost overruns, and limit project delays.

KEYWORDS:

• Concrete
• material quantities
• bridges
• preconstruction estimates
• onsite
• construction

Acknowledgments

This work was supported by EllisDon, Natural Sciences and Engineering Research Council (NSERC), WSP, BASF, and the Ontario Centres of Excellence.

Additional information

Funding

This work was supported by the Ontario Centres of Excellence [OCE TargetGHG 27943]; Natural Sciences and Engineering Research Council of Canada (NSERC) [NSERC CRDPJ 508960].

Notes on contributors

Bolaji A. Olanrewaju

Bolaji Olarewaju completed this paper during his MASc degree. He currently works in construction.

Daman K. Panesar

Daman Panesar is a professor of Civil and Mineral Engineering at the University of Toronto.

Shoshanna Saxe

Shoshanna Saxe is an assistant professor of Civil and Mineral Engineering at the University of Toronto.