According to TS EN 13374, a guardrail system must include one of the following: a main guardrail, a mid-rail, and a toe board, or a mid protection system (such as a fence, net, etc.) and a toe board system. While the main guardrail and toe board are specified as fundamental requirements, for the essential component within the gap between them, it is stated that either a mid-rail or mid protection (such as a railing, fence, safety net, etc.) system can be preferred.
The nets that can be used as a mid-protection system must comply with the requirements of TS EN 1263-1. Net fixings must meet the load requirements of the guardrail classes specified in TS EN 13374. Nets must be tensioned to prevent slackening.
Main Guardrail
The vertical distance between any upper point of the main guardrail and the working surface must be at least 1000 mm. Main guardrails must be continuous, and any horizontal gap should be less than 120 mm.
Toe Board
The vertical distance between any upper point of the toe board and the working surface must be at least 150 mm. Toe boards must be designed to prevent gaps between the working surface and the board. Even if there are gaps, they must be sized such that a 20 mm diameter sphere cannot pass through.
Mid Protection System or Mid Rail
The dimensions of the guardrail system and its components as specified in TS EN 13374 overlap with the values defined in Article 6 of Annex 4 (A) Working at Heights in the Occupational Health and Safety Regulation for Construction Works, although the values in the standard are given in more detail.
Classification of Guardrail Systems
Temporary guardrail systems within the scope of TS EN 13374 are classified into three categories: Class A, Class B, and Class C.
Class A
Class A protection only provides resistance under static loading:
• Provides support to a person leaning on the protection or walking beside it, and
• Stops a person walking toward or falling toward the protection collectively.
Class A should be used at angles less than 10°. The inclination of the guardrail system itself, from the vertical to the working surface, should not exceed 15°. If a mid-rail is present, the gaps should be sized such that a 470 mm diameter sphere cannot pass through. If no mid-rail is present, or it is not continuous, the guardrail system should be dimensioned in such a way that a 250 mm diameter sphere cannot pass through (mid-protection system) (TS EN 13374, 2013).
Class B
Class B protection provides resistance under static loading and low dynamic effects:
• Provides support to a person leaning on the protection or walking beside it, and
• Stops a person walking toward or falling toward the protection collectively;
• Stops a person rolling or falling from a sloped surface collectively (TS EN 13374, 2013).
Class B is suitable for temporary use at angles less than 30° without fall height limitation or at angles less than 60° for fall heights under two meters (Figure 3).
Class B guardrail systems should not deviate more than 15 degrees from vertical to the working surface. Class B guardrail systems should be dimensioned such that a 250 mm diameter sphere cannot pass through any gaps (TS EN 13374, 2013).
Class C
Class C protection provides resistance to high dynamic forces connected to safety requirements to prevent a person from falling from a steep inclined surface:
• Stops a person sliding or falling from a steep inclined surface collectively (TS EN 13374, 2013).
Class C is suitable for use at angles between 30° and 45° without fall height limitation or at angles between 45° and 60° with fall heights under five meters. If the angle exceeds 45° and 60° and the fall height is greater than 5 meters, temporary guardrails are not suitable for protection under the standard. In such cases, the guardrail systems should be brought closer to the working area to reduce the fall height, or for example, guardrail systems should be installed every 2 meters or 5 meters. Class C guardrail systems should be dimensioned such that a 100 mm diameter sphere cannot pass through any gaps.
Static and Dynamic Design Requirements Specific to Temporary Guardrail Classes
In Class A, there is no dynamic loading requirement. It is sufficient for the system to meet the static loads specified in the standard, which will be discussed later in this work. Class B must be designed to meet static loading requirements. In addition to the static loading requirements, any area within 200 mm of the working surface and along the guardrail must be capable of absorbing 1100 J of kinetic energy. Higher components must absorb 500 J of energy.
Class C has no static loading requirement. Class C must be capable of absorbing 2200 J of kinetic energy in any area within 200 mm of the working surface and along the guardrail. Higher components must absorb 500 J of energy (TS EN 13374, 2013).
Examples of dynamic design requirements based on daily work life include:
• If a 70 kg person strikes an area 100 cm above the ground of Class B or C guardrail systems at a speed of 4.32 km/h, or
• If a 10 kg membrane roll strikes an area 15 cm above the ground of Class B guardrail systems at a speed of 53 km/h, or
• If a 0.8 g manometer from an exploding pressurized container strikes an area 19 cm above the ground of Class C guardrail systems at a speed of 266 km/h, the system must be capable of absorbing the impact.
For the examples above, all friction is neglected.