A case study of the ISO13567 CAD layering standard for automated quantity measurement in Hong Kong

Computer-Aided Design (CAD) is widely utilized in the Hong Kong construction industry. However, quantity surveyors and contractors are still extracting material quantities manually from paper drawings. This process is often criticized as mechanical, labour-intensive and time-consuming. On the other hand, it is the most reliable method as the existing automated methodologies cannot be effectively and efficiently applied under the manifold CAD drafting standards. To alleviate the problem, this research proposes an automated solution that adopts the ISO13567 CAD drafting standard. The system has been tested in an air cargo terminal project in Hong Kong. The results indicate that the proposed solution is on average 10 times faster than the manual approach. It achieves a measurement accuracy of up to 99% for a correctly structured CAD drawing. Nevertheless, there are barriers that undermine the results and hence the use of the system in practice. The outcomes of this research have been presented to the Construction Industry Review Committee of the Hong Kong Government. Following a consultation study commissioned by the Government, a local CAD drafting standard called the CAD Standard for Works Projects (CWSP) was launched in September 2002. As enforced by the corresponding contract provisions, project parties to public works contracts are now sticking to CSWP, and thus practical use can be made of the proposed system after the necessary modifications have been made.