Worker Tracking & Safety Monitoring in Construction

One of the main challenges facing the technology was to create a network within underground tunnels and another was to provide products that can withstand harsh working environment. The team used amplifiers to enhance bandwidth and Litum produced IP67-rated hardware that is durable for harsh working conditions.

Litum designed an RTLS system developed with UWB RFID technology, which utilizes RTLS tags (transmitters) and RTLS anchors (receivers) that operate on a mesh network structure.

Litum manufactured the system, including the RTLS UWB anchors [readers], tags, firmware and software in addition to providing installation and ongoing support. In the tunnel itself, 48 anchors (readers) were installed that capture transmissions from the badges. Each anchor has a read distance of 150 meters (492 feet) aboveground and about 100 meters (328 feet) in the tunnels.

The tags of workers are matched with their ID’s and worn by attaching their helmet. The system wirelessly forwards each tag ID, along with its location to the gateway anchor via the mesh network structure. The gateway then forwards the data to the Litum’s cloud based software in order to update the individual's position and movement. The precise location of tags is calculated by Litum's location engine software by using proprietary algorithms. That location can be calculated with an accuracy of about 50 centimeters (19.7 inches). Thus, as each worker moves around the worksite and through the tunnel, his or her location is displayed on a dashboard map as a dot. In that way, management can view where all personnel are located in real time, as well as collect and store historic data.

In the event of an incident, such as an unauthorized individual entering a restricted area, an alert is issued directly to managers or supervisors onsite, who can then quickly address the problem. In case of the emergencies that might take place onsite, system manager can send alert to employee badges individually or collectively to warn them. In addition, RTLS UWB nodes are installed throughout the tunnel, every 100 meters (656 feet). Those nodes come with a button that can be pressed to activate the alarm system, which enable workers to activate alarm system if needed. The two-way nature of the communication makes emergency alarm management easier. When alarm activated, evacuation is safer and much safer through the software that displays each worker's location.

• Paris Metro has used the system for firefighting exercises ever since it was installed. The technology proved useful during those exercises.

• Managers could follow the progress of their staff from the control room.

• With regard to alerting, the system sends automated e-mail alerts to personnel and managers related to maintenance requirements or other factors.