Automation of Quantity Take-off for Modular Construction

Abstract

Quantity takeoff, serving as a foundation for the downstream tasks in the construction management, is a repetitive work. However, this process in current practice involves massive manual interventions, which is extremely time consuming and highly error-prone. This is partially due to the fact that incorporating cost breakdown structure formulated according to industry companies’ classification system into BIM still remains a challenge. This study thus exploits a methodology which allows construction practitioners to obtain quantity takeoff in an automatic manner. The main concept is to pre-load the unique classification information into the BIM model such that the quantity of materials in a given BIM model can be extracted and stored into a database (Excel Sheet) automatically in according with the preloaded classification system. Besides this, the unique classification information, along with formulas for derivedquantities, is front-loaded into the Excel Sheet database. As a result, the explicitly extracted quantities are converted by the preloaded formulas to the required format for the purpose of ordering and purchasing. A prototype system is developed based on Autodesk Revit through Revit Application Programming Interface. A case study of a modularized house reveals that a considerable amount of time saving and accuracy increasing of project estimation are achieved as a result of achieving the quantity takeoff automation.