On construction sites, workers and visitors often face risks such as falls, exposure to hazardous materials, heavy equipment and work at height. To minimise these risks, safety signs are indispensable. This visual communication system not only warns of potential hazards but also guides people and supports safe procedures in the workplace. Knowing and applying the different types of safety signs is therefore essential to protect the physical integrity and health of everyone involved.
Safety signs follow specific standards designed to ensure clear and direct communication. Therefore, each sign must be positioned strategically and visibly so that it fulfils its function of alerting, preventing or guiding. Conversely, a lack of suitable signs can significantly increase risks and compromise the safety of everyone involved.
Types of safety signs on construction sites
Safety signs can be classified according to their main purpose and the information they convey. In Portugal, these signs follow European regulations and use specific colours, shapes and pictograms to make them easier to understand.
Warning signs
First, warning signs alert people to potential risks in the workplace. This type of sign is usually triangular, with a black pictogram on a yellow background and a black border. Its main function is to alert workers and visitors to a hazard, so that they can take precautions before approaching the marked area.
Common examples of warning signs:
- Electric shock hazard warning
- Toxic substances warning
- Fall hazard sign
These signs should therefore be placed in strategic, highly visible locations, especially in areas where the risk is permanent or very high.
Mandatory signs
Mandatory signs, in turn, indicate compulsory actions that workers and visitors must follow to ensure safety on site. These signs are circular, with white pictograms on a blue background. They give instructions on the use of personal protective equipment (PPE) or on specific rules for entering or working in certain areas.
Common examples of mandatory signs:
- Safety helmet must be worn
- Ear protection must be worn
- Mask or respirator must be worn
These signs are thus essential to ensure that everyone follows safe practices, especially in areas with a high risk of accidents.
Prohibition signs
Similarly, prohibition signs aim to restrict behaviour that could increase the risk of accidents or compromise safety. They are circular, with a red border and diagonal bar, a white background and a black pictogram. This type of sign prohibits actions that could put physical integrity at risk.
Common examples of prohibition signs:
- No smoking
- No mobile phones
- No unauthorised access
In this way, prohibition signs help maintain control in hazardous areas and support strict compliance with safety rules.
Emergency signs
This type of sign indicates emergency exits, first aid points, emergency equipment and evacuation routes. Emergency signs are crucial in situations that require rapid evacuation or immediate assistance.
Emergency signs are usually square or rectangular, with white pictograms on a green background. They must be highly visible and illuminated, so that people can identify them quickly in low light or during an emergency.
Common examples of emergency signs:
- Emergency exit sign
- Evacuation route sign
- First aid kit sign
Firefighting equipment signs
Likewise, these signs show the location of firefighting equipment, such as fire extinguishers, hydrants and hoses. They are rectangular or square, with white pictograms on a red background. Using these signs correctly is vital so that, in the event of a fire, workers and visitors quickly know where to find firefighting equipment.
Common examples of firefighting equipment signs:
- Fire extinguisher location sign
- Fire hydrant sign
- Fire hose sign
Temporary hazard signs
Construction sites are dynamic environments where risks can change constantly. For this reason, temporary hazard signs mark short-term dangers such as wet floors, changes in level, excavations and areas closed off for a certain period. This type of sign is usually portable, so it can be moved as needed.
Common examples of temporary hazard signs:
- Slippery floor sign
- Work in progress warning
- Restricted area sign
Therefore, these signs are essential to maintain safety in areas that change frequently and require extra attention from workers.
Implementing and placing the different types of safety signs on site
Correct placement of safety signs is crucial to their effectiveness. All types of signs must be visible and clear so that workers can identify them effortlessly. In addition, signs must be understandable to everyone, using universally recognised symbols and, where necessary, instructions in different languages.
It is also advisable to review sign locations regularly, especially on sites where the layout can change quickly. In noisy or poorly lit environments, visual signs may also need support from other means of warning, such as acoustic signals and lighting.
The legal framework for safety signs
In Portugal, Decreto-Lei n.º 141/95 and Portaria n.º 1456-A/95 set out the minimum requirements for health and safety signs at work. Together, they transpose Directive 92/58/EEC into Portuguese law. Indeed, these laws cover more than signboards. They also cover illuminated signs, acoustic signals, verbal communication and hand signals, such as those used to guide crane and machinery manoeuvres. In addition, the ISO 7010 standard harmonises pictograms and identifies them by codes: W for warning, M for mandatory action, P for prohibition, E for emergency and F for fire.
Summary of colours and shapes
| Type | Shape | Safety colour |
|---|---|---|
| Prohibition | Circular | Red, with a white background |
| Warning | Triangular | Yellow, with a black border |
| Mandatory | Circular | Blue |
| Emergency and rescue | Rectangular or square | Green |
| Firefighting | Rectangular or square | Red |
On the other hand, obstacles and places with a risk of falling or collision can be marked with alternating yellow and black stripes, or red and white stripes.
Practical example: Signs at a work front
Consider a work front with excavation, moving machinery and work at height. At the entrance, a single panel shows the requirements to wear a helmet, a high-visibility vest and safety footwear. Next to the excavation, there are fall warning signs and barriers with yellow and black stripes. Finally, in the manoeuvring areas, the banksman uses standard hand signals. As a result, each risk has the right signs, without an excess of signboards.
Common mistakes to avoid
A frequent mistake is to put too many signs in the same place, which dilutes the message. Another is to keep signs that no longer correspond to any risk, because workers then stop paying attention to them. Finally, many sites keep faded or dirty signs that lose visibility.
Safety signs checklist
- Signs comply with Portaria n.º 1456-A/95 and ISO 7010.
- Signs included in the health and safety plan.
- Emergency signs visible in low light.
- Signs reviewed at every change of site phase.
- Workers trained on the meaning of the signs.
Frequently asked questions
Can I create my own signs?
Only when no standard pictogram exists, and provided that the legal colours and shapes are respected. In general, you should use the ISO 7010 pictograms, which everyone recognises.
Conclusion on the types of safety signs
Safety signs on construction sites are vital to protect everyone in the construction environment. When implemented strategically, they guide, warn and protect workers and visitors. As a result, they minimise the risk of accidents and promote a safe and productive workplace. Each type of sign plays a specific and essential role in site safety, and its use should follow good practice and current regulations.
Understanding and following signage guidelines is the responsibility of everyone involved, from managers to the workers themselves. All of them must be aware of what the signs mean and why they matter. Investing in safety signs not only reduces risks but also improves efficiency and organisation in the workplace, promoting a safety culture that benefits everyone.
See also: The importance of safety signs on construction sites, Best practices for safety sign placement on construction sites and Temporary and permanent signage on construction sites.
For more information on legal obligations for safety at work, visit the Authority for Working Conditions (ACT), the Portuguese labour inspectorate.