RFID-based life cycle tracking of precast concrete units

Finding accurate information on the status of materials is cited as one of the most common causes of non-productive time in construction projects. Materials are often misplaced or even go missing, resulting in countless hours spent searching for them. Sometimes they are never found. Since contractors are working on tight deadlines, missing components have to be re-ordered or re-fabricated, leading to additional costs and possibly penalties for late delivery. This can have a negative impact on productivity and project performance, and lead to problems with schedules, budgets, and quality.

Top: RFID chips are tied to the rebar at a predetermined location before concrete is poured. The encapsulated RFID tag is placed in the area shown by the red circle.

Centre: RFID chips are read with a handheld scanner.

Bottom: Tunnel segments stored in the Woodstock plant all contain RFID chips that can be scanned through the concrete.

The application of information technology for tracking construction materials can provide an accurate and efficient means for reducing time and resources being spent collecting and managing data. In a recent example, the NRC Centre for Computer-assisted Construction Technologies (NRC-CCCT), in collaboration with Armtec, a leading infrastructure and construction company, has developed a system for tracking precast tunnel liner segments manufactured in Armtec’s Woodstock, Ontario plant. The system relies on commercially available encapsulated Radio Frequency Identification (RFID) tags which, during the fabrication process, are embedded in the liner segments. As the segments move through the plant, their status (i.e., fabrication, quality, storage and shipping) and associated data are updated by the field crew using mobile computers.

Armtec is using the system in its Woodstock plant to track the fabrication and inventory data for 58,000 tunnel liner segments being supplied for the York-Spadina subway extension project in Toronto, which involves construction of two 6.5 km tunnels.

The system helps reduce time and resources spent locating concrete units in the storage yard and managing production and quality control data. Another key benefit of the system is that it generates the product handover documentation in electronic format that many asset owners are now requesting.

Apart from helping reduce inefficiencies in the fabrication process, RFIDs and linked data in the tracking system also provide many benefits in the construction and maintenance phase. For example, the product handover documentation is currently used by Toronto Transit Commission (TTC) construction contractors working at the subway site to validate the materials received.

In the long term, the embedded RFIDs and associated fabrication data will help TTC, as well as other infrastructure owners, to improve the maintenance and rehabilitation of a tunnel over its lifespan. The embedded RFID chips in infrastructure systems like bridges and tunnels have the potential to help owners to locate damaged pieces during operation and maintenance.

The RFID-based system offers significant advantages over the paper-based system, which is still the most prevalent method in the construction industry. While it provides all of the functionality of paper-based tracking systems, the RFID system has the added benefits of reduced user input time, faster data communication and fast record searching.

For more information, contact Ajit Pardasani at 519-430-7085 or ajit.pardasani@nrc-cnrc.gc.ca.