Maintenance accidents: what the INAIL data say and the recurring dynamics

What the official figures say

The data published by INAIL (the Italian National Institute for Insurance against Accidents at Work) in its annual reports and in the bulletins of its Statistical-Actuarial Advisory provide the general context of workplace accidents in Italy. In 2023, 590,215 accident reports were recorded, of which 1,147 were fatal. In 2024, excluding students, reports fell to 511,688 (-0.7% compared with the previous year); cases occurring during work fell by 1.9%, while commuting accidents grew by 5.0% — source: inail.it, bulletin of the Statistical-Actuarial Advisory, February 2025.

The aggregate figure does not automatically distinguish maintenance from other activities: for targeted analyses, INAIL provides two tools:

• the INAIL statistical database (bancadaticsa.inail.it), which can be queried by economic activity, occupation and mode of occurrence;
• the National surveillance system for fatal accidents (Infor.MO), which collects and classifies the dynamics of fatal and serious workplace accidents in Italy, managed by INAIL.

These are the correct sources for quantifying the weight of maintenance accidents in a specific sector, and they are where anyone conducting a risk assessment should start — not from anecdotal literature.

Note: this article does not report percentages or specific cases without a reference to a verifiable primary source. The dynamics described below are drawn from the technical and regulatory literature, not from statistics presented as such.

Why maintenance is a critical phase

The INAIL reports themselves acknowledge that maintenance concentrates specific risk factors. In the 2023 annual report, presented in October 2024, INAIL explicitly cites — among the most well-known cases of the year — the accident of 30 August 2023 in Brandizzo (Turin), in which five railway track maintenance workers lost their lives, struck by a train: an event that, although not strictly about LOTO, is emblematic of the structural risk of maintenance activities on potentially active plants.

In principle, maintenance concentrates four conditions that raise the risk:

• the operator works physically inside or on the machine, in spaces designed to be closed during normal operation;
• it is often necessary to temporarily disable protections (guards, covers, interlocks) to access the components;
• the work takes place in narrow time windows (planned shutdowns, shift changes), under operational pressure;
• it involves several operators and sometimes several teams who must coordinate.

These four factors are part of the rationale that led to the publication of UNI EN 17975:2025 and, before that, of UNI EN ISO 14118:2018 on the prevention of unexpected start-up.

The documented recurring dynamics

The international technical and regulatory literature (OSHA guidelines, materials from the European Agency for Safety and Health at Work, the ISO 12100 and 14118 series of standards) documents four families of dynamics that recur in accidents during maintenance, regardless of the sector.

Unexpected machinery start-up

The operator works with the machine stopped, believed to be safe. The machine restarts during the operation for various causes: a command sent by another operator unaware of the maintenance technician's presence, an automatic reset after an alarm intervention, a spurious signal in the control circuits, a software error, a reset from the HMI done "just to check".

It is the risk category that gives UNI EN ISO 14118:2018 its title. The countermeasures are design-based (mechanically lockable disconnectors, consent devices, safety logic) and organizational (LOTO procedure applied, Try-Out verified).

Accumulated residual energy

Isolation has been applied correctly, but inside the plant there remains accumulated energy that has not been dissipated: charged capacitors, pressurized hydraulic accumulators, compressed springs, suspended weights, hot fluids in intercepted but undrained lines.

These are accidents that happen to trained and disciplined staff, because the source of risk is invisible and static. The 17975 addresses them by requiring, in the procedure, a complete analysis of all forms of energy (kinetic, potential, thermal, chemical, electrical) and — where applicable — dissipation/ draining before the start of the operation.

Sequence and identification errors

The maintenance technician isolates the wrong machine, or isolates the right machine but at the wrong point (a secondary disconnector instead of the main one), or removes an isolation before the conditions allow it (releasing the parent before the children, see the article dedicated to parent/child lockout).

These are typical dynamics of complex plants and shift changes. The countermeasures are procedural (unique identification of isolation points, LOTO diagrams consultable on site, written sequences) and organizational (shift change with a formal handover of the state).

Involvement of third parties not warned

A production operator, a worker in an adjacent activity, an external contractor acts on the machine without knowing that it is under maintenance: they operate a control, remove a tag "to do some cleaning", reopen a manual valve. These are the classic communication and territory errors.

The countermeasures: visible and standardized tagging, physical perimeters (barriers, lock-boxes), formal communication at the start and end of the operation, an audit trail that can be consulted in real time.

What changes with UNI EN 17975:2025

The value of the new European standard lies in systematizing the organizational countermeasures that machinery standards (UNI EN ISO 14118, UNI EN ISO 12100) require on the design side.

Reinforced isolation (RI) as the default, the introduction of the Try-Out as a mandatory step, the formalization of the parent/child lockout processes, the obligation of structured training: each one responds to one of the families of dynamics described above. They are not abstract prescriptions, they are responses to documented accident patterns.

How to use the data in your own risk assessment

For those who need to update their risk assessment document (DVR) and LOTO procedures under the 17975, a pragmatic sequence:

1. Query the INAIL database by filtering by your ATECO (economic activity) code and by mode of occurrence, to get the real picture of your sector.
2. Consult the cases of the Infor.MO system for detailed dynamics of serious and fatal accidents published by INAIL in your sector.
3. Compare the recurring dynamics described above with your own typical maintenance activities: which are covered by the existing procedures, which are not.
4. Map the 17975 countermeasures (reinforced isolation, Try-Out, parent/child, role-differentiated training) onto the identified risk points.
5. Document the choices, including the justified omissions (e.g. when SI is adopted instead of RI for technical reasons).

It is a tedious exercise, but it is the trail an inspector can follow to verify that the risk assessment is real and not formal.

The Eurosystem experience

In the pharmaceutical sites where we operate, updating LOTO procedures to the 17975 has in every case required a review of the pre-existing risk scenarios, not a simple rewrite of the document. The four families of dynamics described above are the filter we apply to discover where the previous procedures formally covered the risk but operationally did not eliminate it — typically on residual energy and on sequence errors in plants that have grown by stratification. It is often there that the real opportunities for improvement are hidden.

Sources consulted

• INAIL — 2023 Annual Report (presented in October 2024) and the bulletin of the Statistical-Actuarial Advisory, February 2025: inail.it
• INAIL — Statistical database: bancadaticsa.inail.it
• INAIL — National surveillance system for fatal accidents (Infor.MO)
• UNI EN ISO 14118:2018 — Safety of machinery, prevention of unexpected start-up
• UNI EN ISO 12100:2010 — Safety of machinery, general principles for design
• UNI EN 17975:2025 — Maintenance, process for managing risks related to energies and fluids
• EU-OSHA — European Agency for Safety and Health at Work, educational materials on maintenance safety