When using a movable lifting working platform (MEWP) with bypass mechanisms or stabilizers, it is first necessary to carry out an assessment of the strength and condition of the ground. This can range from a visual inspection to a complete geotechnical survey and must be carried out by someone with adequate training and knowledge to ensure the safety of all who work in the field.
In most cases, a visual risk assessment is required (perhaps with the additional use of a specialized calculator to determine the size of the spreader plate), and the inspection should include the general condition of the ground, any adjacent or underground hazards, the weight of the access machine used and the use to which it will be applied.
An important aspect of ground control is the bearing capacity of the soil. This means that the maximum pressure can support a specific soil area. In order to use an air working platform, this power must be known so that the pressure generated by MEWP does not exceed it. If a computer is used on the ground with power that cannot cope with the load or pressure, then the operators risk an unstable platform that could tip over. Other cases that may pose a danger to users include areas where there are underground open-air spaces, such as sewer pipes, subways, basements and tunnels. In these situations, a thorough ground inspection is necessary, and distribution plates should always be used with supports.
To determine the type of spreader plate outside the riger, it is necessary to make a calculation based on weight, force and pressure. In this situation, this means the weight of the MEWP (which can be found in the user manual), the force that the platform to work with the antenna imposes on the ground through the outrigger supports, and the pressure imposed by this force. Distribution plates are used to distribute this load over a larger area, which reduces the pressure of the machine to the ground. This is necessary when working with uneven, unstable and loose soil conditions, but it is recommended that distribution plates are always used in case of unknown hazards.
Sometimes it is necessary to take further steps to ensure safety under poor conditions, such as additional preparation or foundation. They are usually supplied in the form of wooden mats, steel grills or concrete pads. Both foundations and expander mats should never show distortion when a load is imposed on them. If this is visible, you will need to find a more adequate form of support. The general recommendation is that spreading plates with a diameter of up to 600 mm should be at least 25 mm thick. Distribution plates with a diameter of 900 mm require a thickness of at least 50 mm. For spreading plates over 900 mm wide, request professional guidance.
When using spreading plates and ejectors with an aerial work platform, such as a cherry picker or boom lift, make sure that you conduct proper surveys at the facility and use suitable equipment in accordance with the ground conditions and the weight of your computer with power to ensure the safety of your workers.
