How to Plan Safety and Coordinate Subcontractors on a Construction Site

Contractors, subcontractors, self-employed workers, and suppliers may all be present on a construction site. Their activities can create risks affecting different teams: a delivery may interfere with workers’ passage, and work at height may expose those working on lower levels. Coordination of business activities (CBA) helps organize these interactions, as well as meet the applicable preventive obligations.

In Spain, the general framework is based on Article 24 of Law 31/1995 on the Prevention of Occupational Risks and is developed in Royal Decree 171/2004. Construction sites are also governed by Royal Decree 1627/1997, which sets out specific rules, including those relating to the health and safety study and plan and to coordination during execution. These are related frameworks, but they are not interchangeable.

Clarify the roles before work begins

CBA covers concurrent businesses, the employer in control of the workplace, and the principal employer. Each role has its own scope; they should not be assigned solely on the basis of the name a company is given on the construction site.

• Concurrent businesses are the businesses and self-employed workers who share a workplace or carry out activities there. They must cooperate, exchange information about the risks arising from their work that could affect other people, and take the information they receive into account when planning their activities.
• The employer in control of the workplace is the party with the authority to make the workplace available and manage it. Its obligations depend, among other things, on whether it has its own personnel present there.
• The principal employer is the party that contracts or subcontracts work or services forming part of its own activity at its own workplace. The presence of multiple businesses is not, by itself, enough to assign this role: the conditions set out in the regulations must be analyzed.

In construction, there is also the health and safety coordinator during execution, appointed by the project owner when more than one business is involved, when one business is involved together with self-employed workers, or when several self-employed workers are involved, as provided for under RD 1627/1997. This role is not the same as the person responsible for coordinating preventive activities under the CBA framework. The INSST warns that these are distinct functions, although, where appropriate, they may be carried out by the same person.

Plan based on the actual work

Before businesses arrive on site, gather the information needed to understand what will be done, where, and when. For each activity, identify the phases, equipment, and areas involved, the people who could be affected, and the risks that may arise from interactions with other work.

Planning must connect tasks to the specific conditions on site. A generic job risk assessment does not replace specific information about risks arising from the contracted activity that could affect other businesses. If the planned sequence includes simultaneous or nearby operations, define in advance how interference will be prevented and who will check that the agreed measures are being implemented.

On construction sites, the health and safety plan has a specific role under RD 1627/1997: it develops and adapts the study or basic study to the site and to the means and methods planned by the contractor. It should not be confused with a generic CBA file or treated as a substitute for cooperation and the exchange of information between businesses.

Exchange useful information, not just files

Preventive information must reach those who can act on the risk: site managers, supervisors, affected workers, and concurrent businesses. Depending on the circumstances, the exchange may include site-specific risks relevant to other activities, preventive and emergency measures, the specific risks introduced by each business, and the instructions needed to work safely.

Rather than simply requesting a standard document package, check that the information relates to the work and conditions on that site. For example, it is not enough to know that a business carries out electrical work: it may be necessary to know the area affected, when the work will take place, and the restrictions that other teams must observe. Concurrent businesses must also report accidents or situations that could affect personnel from other businesses.

The documentation that must be exchanged or retained depends on each business’s role, its activities, and the applicable regulations. Do not treat every commercial document checklist as a universal legal requirement: the objective is to demonstrate and make effective prevention possible, not to accumulate paperwork unrelated to the risks.

Coordinate incompatible work and interference

Once planning and information have been shared, establish how work that may interfere with other activities will be organized. It may be necessary to separate areas, stagger tasks, mark out access routes, establish procedures for deliveries and unloading, or agree on who gives notice before an operation begins. The specific measures depend on the identified risks; they must be communicated to the affected businesses and be understandable to those carrying out the work.

RD 171/2004 provides for various means of coordination. These may include exchanging information, giving instructions, holding meetings, or appointing people to coordinate preventive activities. The latter is considered a preferred means when two or more of the conditions set out in the regulations apply, such as particular difficulties in controlling interactions that could create serious or very serious risks, preventing incompatible activities, or coordinating a complex construction site because of the number of businesses, workers, or activities. The regulations require those people to have preventive training corresponding, at a minimum, to intermediate-level functions. The choice must reflect the circumstances and ensure that coordination objectives are met.

Review coordination when site conditions change

Initial planning is not enough if the phases, work areas, businesses present, methods, or equipment change. When a change could affect the safety of other businesses, update the information and measures, notify the relevant parties, and check that activities can continue under the new conditions.

A monitoring routine can be based on three questions: What has changed? Who might be affected? What measure or instruction needs updating? Meetings and on-site checks are useful when they help resolve specific interference and make clear who must take action. Coordination must continue throughout the work; it should not be limited to the initial access check.

A practical sequence for the business

1. Define the activities and businesses involved before work begins, including the work of self-employed workers and suppliers where applicable.
2. Determine the legal roles of each party without assuming that the employer in control of the workplace, principal employer, contractor, and coordinator are equivalent roles.
3. Identify risks and interference by phase, area, schedule, equipment, and concurrent activity.
4. Share preventive information and instructions with the businesses and people who must apply them.
5. Agree on coordination measures proportionate to the complexity and risk, and clarify who communicates and verifies them.
6. Review the agreements when changes, incidents, or new interference arise, and update the planning when necessary.

The reference point is Spanish legislation on the prevention of occupational risks and health and safety on construction sites. The specific allocation of obligations depends on the functions actually assumed and the circumstances of each site; this guide offers general criteria and does not replace preventive assessment or legal analysis of the case.