Ensuring the safety of workers inside confined spaces is a critical activity in the field of construction and maintenance because of the high risk involved in working in such environments. Perhaps it would be useful, first of all, to know what is meant by confined spaces. There are two main types of confined spaces: the so-called ‘open’ ones, which are those with an opening in their upper part and of such a depth that it makes their natural ventilation difficult (vehicle lubrication pits, wells, open tanks, tanks),…) and ‘closed’ ones with access openings (storage tanks, underground transformer rooms, tunnels, sewers, service galleries, ship holds, underground manholes, transport tanks, etc.). Workers entering these confined spaces are exposed too much greater risks than in other areas of construction or maintenance and it is therefore essential to apply extreme caution.

Each confined space has specific characteristics (type of construction, length, diameter, installations, etc.) and specific associated risks, which means that they require solutions that are highly geared to their specific safety needs.

The ‘conventional’ risks specific to confined spaces are mainly oxygen suffocation, inhalation poisoning of pollutants and fires and explosions. But new ’emerging’ risks from exposure to new building materials such as nanoparticles and ultrafine particles are also emerging. In addition, as research into new materials improves, there is also a better understanding of their potential negative effects on human health and how to prevent them.

The truth is that the training of workers and current safety regulations seek to anticipate risk situations before they occur in order to avoid them and thus prevent the appearance of accidents. But several problems arise: on the one hand, the regulations are not always strictly observed (whether due to workload, carelessness, fatigue, etc.) and on the other hand, there are always inevitable risks. In the case of carelessness, systems can be proposed to minimise this type of error and in the case of risks that cannot be avoided, systems can be proposed to detect them early and plan the corresponding action protocols.

It should be noted that risk situations do not usually appear suddenly and in most cases are detectable in time to avoid personal misfortunes. There are several problems: the detection of these risks is usually done with specific measurements using the portable equipment that the workers must carry, many times the workers are not controlled to access the premises with the corresponding protection equipmente and almost never a continuous monitoring of the indoor atmosphere is done.

In recent years, new technologies and equipment have been developed that can be applied to improve security in this type of environment and reduce the associated risks.

In this type of environment, an effective risk prevention system should be based on technological solutions capable of providing answers to safety aspects throughout the entire work cycle in confined spaces: Before entering the space itself, during all work inside the enclosure and when leaving the work space (whether it is at the end of normal work or by evacuation).

The latest confined space air quality monitoring systems are based on multisensorial technology that combine different detection systems to ensure the best possible conditions to avoid or reduce the risks present in the confined spaces.

Advanced data processing techniques (machine learning, data mining, predictive algorithms) are also being applied, enabling much more efficient and rapid information extraction.

In the same way, great advances have been made in access control and personnel tracking systems, allowing us to know the position of each worker and even his or her vital signs in order to detect almost immediately any problem that may arise.

Finally, it should be noted that the use of robots and autonomous vehicles (land and air) equipped with different types of sensorization are increasingly being used to determine the conditions of a site before it is accessed. This is especially useful in those where there may have been an incident: power failure, collapse, fire,… or simply because environmental conditions are suspected to have changed and the reason is unknown.

CARTIF has been working on these issues for many years now, both in safety projects in critical construction environments (PRECOIL, SORTI) and in specific systems for tunnels and underground works (PREFEX, INFIT, SITEER).

In short, the development and implementation of new specific technologies can help to save lives in such a critical environment as confined spaces.

José M. Llamas
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