Construction site safety

Five reasons IoT wireless geotechnical monitoring is key to reducing safety risks.

By Juan Perez

Construction sites are dangerous places. With so much heavy machinery and a lot going on in one place, it’s no surprise that one in 10 construction workers is injured every year (https://blog.capterra.com/13-shocking-construction-injury-statistics). Most construction sites already have safety measures in place — such as training, worker uniforms, signage, and strict procedures — but in spite of all this, accidents still happen (www.ehstoday.com/construction/construction-accidents-risks-facts-and-repercussions-infographic).

Some risks are unavoidable, but others — those provoked by geotechnical problems for example — can easily be predicted and prevented with the right technologies in place.

Research suggests that the construction industry is not using these technologies and is lagging behind in the adoption of information systems. This is reflected in the fact that 47 percent of construction managers still use manual methods to collect important project information (https://link.springer.com/chapter/10.1007/978-3-642-35548-6_104). This increases site risks, as project managers do not have access to the necessary real-time data to predict and prevent incidents from happening — either because they are using manual or non-remote data-gathering, or because the internet of things (IoT) system they’re employing is not up to scratch.

Effective IoT wireless monitoring (https://blog.worldsensing.com/industrial-iot/digitizingtunnelmonitoring) could significantly improve site safety if it was more widely adopted by the construction industry. Remote site monitoring based on IoT works by using several technologies to wirelessly and remotely collect data about the status of the project from nodes installed at key points on the construction site. Considering the size, different phases of construction, rate of change of the measured parameters, and difficulties to externally power the sensors, low-power wide-area networks (LPWAN) are the most suitable technologies, enabling deployment of nodes powered by internal batteries and allowing long-range communication.

Table 1 compares some of the wireless options available in the geotechnical monitoring market today.

The nodes “sense” what is going on around them, transmit this information remotely to a gateway, and then to a server, where the information can be processed by the appropriate software and turned into actionable insights. Monitoring based on LPWAN technologies is a key geotechnical innovation that, when high quality and used properly, can help prevent accidents on construction sites. Following are five reasons why it is essential for construction site safety.

Real-time, remote data collection — Real-time data collection, now a standard part of most infrastructure or site-monitoring solutions, is essential to site safety because it allows anomalies in the status of different parts of the site to be flagged as soon as they occur. This means that something that might be a minor change can be dealt with immediately rather than turning into an incident — such as a landslide — that costs both money and human lives.

Accidents can happen anytime, so data from sensors has to be collected regularly to anticipate any issues. Remote data collection adds to increased site safety because areas of the site that are difficult or dangerous for workers to reach can be monitored at a distance. Monitoring systems that use LPWAN network technologies ensure that little to no monitoring system maintenance is needed.

In France, wireless monitoring is being used to greatly increase site safety for the Grand Paris Metro Project (https://www.vinci.com/vinci.nsf/en/newsupdate/pages/grand_paris_express_the_
biggest_infrastructure_project_in_europe.htm), significantly reducing risks to employees and citizens through deployment of more than 400 Loadsensing wireless data nodes installed deep in the basements of the surrounding structures.

Remediation and predictive maintenance — Wireless monitoring systems constantly collect data about the status of the project. While construction site managers can more accurately plan maintenance to make sure that no incidents occur, the data collected gives details of the causes, not just the early warning signs, of changes or incidents.

A retaining wall in an excavation may collapse anytime due to poor drainage. Through wireless monitoring, the stability of the wall as well as the water pressure that can affect the structure can both be monitored to anticipate any accidents.

Being able to build up a picture over time of the key causes of incidents helps construction site managers predict accidents even before detecting any disturbances and allows them to develop a long-term maintenance strategy that more accurately prevents accidents.

Engineering design validation — Data gathered about the status of the construction site through wireless sensors helps validate the design of the structure and the retaining system. Engineers study all possible outcomes and scenarios, but no plans can ever be 100 percent foolproof. Supported by a wireless monitoring system, engineers can spot potential flaws in the design or any changes or unexpected factors in the surrounding environment that were not originally factored in. This means that the design can be changed or remedial actions implemented at the beginning of the project, before any problems are so entrenched that lives are put at risk, accidents occur, or it costs a lot of money to resolve them.

By measuring the load of ground anchors in a construction site, construction engineers and managers can see if they have been designed properly or not, and in turn if they need to modify the design or perform remedial actions — such as placing a berm — before they get too far into the project or before an accident occurs.

Being able to validate a design is particularly important for large infrastructure projects, such as the Cisomang Bridge Refurbishment in Indonesia where wireless data nodes are monitoring strain gauges on the bridge pillars, which had to be refurbished after they were deformed, posing a huge safety risk. These nodes not only ensure the safety of the workers and motorists but also help validate the new, safer design for the pillars.

Easy installation — Wireless data nodes are plug and play and also are compatible with most sensors. They can be installed at the beginning of a project and may be relocated or expanded through the course of the project. This offers an advantage compared with other types of monitoring systems, such as cable monitoring, which require frequent maintenance and are difficult to move around, interfering with a rapidly changing construction site.

With wireless sensors, even if the construction moves forward or the site changes, they can adapt to the changing environment. As soon as they are installed, they begin collecting data; this means that operators and managers can know about the status of the project without needing to maintain the monitoring equipment from the very beginning to the very end of the project, allowing for a comprehensive picture of what is happening.

Before, gathering this much data comprehensively with cables or sporadic manual readings was expensive and tedious. But with a wireless system, it is rendered much easier and cheaper. Construction site managers can use the data from one project to build models and plan better for future projects.

One example is the LA Purple Line Metro Extension Project (https://www.worldsensing.com/success-story/tunnel-monitoring-north-america), where data nodes are placed in boreholes on the sidewalk. These nodes measure ground displacements induced by tunneling at different depths and in real time, ensuring that the surrounding area, where people live, is always safe.

Safety — In many projects, monitoring through cabling or wireless means is nonexistent, and this is where the risks and potential costs are the highest. Wireless monitoring is logistically more practical for a dynamic site than monitoring with cabling. It is also a much more cost-efficient way to ensure safety onsite. Each day a project is delayed costs a lot financially. For example, a project that has a contract value of $50 million with a duration of three years has a value per day of $45,662. If the average delay is 30 percent, the average cost of delay is just less than $15 million.

Accidents and incidents are the main cause of work stoppage and delays, so if they can be prevented and predicted, a construction project can smoothly reach completion with the least number of delays, meaning less extra costs — both in terms of budget and human lives. There is no price tag for a person’s life, so the aim is for a project to be completed without any health hazards or casualties; wireless monitoring can help alleviate this common concern.

Projects that can prove that there will be fewer risks through implementing a remote system with proof-of-concept will also have lower insurance costs. When an insurance company sees that a construction project has such monitoring systems in place, it gives them a sense that the management team will be able to anticipate accidents and therefore comply better with their insurance policies.

Conclusion

Many engineers and construction site managers have had bad experiences with wireless monitoring because of poor implementation or equipment, but this doesn’t have to be the way. With the right IoT-based system and provider, construction sites can be rendered a lot safer for minimum costs. The “right” provider is one who offers to tailor its monitoring system to the project’s specific needs, who has proven experience in the field, whose technologies are well-reputed, who offers proof-of-concept before full deployment, and who guides implementation of their solution from start to finish, offering advice and consultation along the way.

Overall, insights into the status of each part of the construction site provided by wireless sensors — particularly in terms of validating the design — allow construction site managers to go even deeper into their project, allowing them to do a better job of keeping their sites safe, efficient, and productive places.

Juan Perez is a geotechnical engineer with more than 14 years of experience and knowledge of geotechnics, construction site management, instrumentation, data management, data acquisition systems, and LPWANs. The product owner of the globally recognized wireless monitoring system Loadsensing has been leading the product development of wireless monitoring at IoT pioneer Worldsensing (www.worldsensing.com) since 2013.