What are the guidelines for using a mobile access tower when it is windy?
Wind has a major effect on the stability of mobile access towers because it imposes loads that can overturn the tower.
If the average wind speed reaches 17mph (Beaufort 4, 27km/h or 7.6m/s) you should cease work and dismantle the tower.
But, before you build the tower, check the weather forecast as part of your risk assessment and make sure the weather conditions, including the expected wind speed, mean that you can go ahead. Then, when you’re working on the tower, monitor the wind speed. You can do this using a hand-held wind speed device (anemometer).
You should never attach netting, boards or sheeting to a mobile access tower. These act like sails and, even in relatively light winds, they can easily cause the tower to overturn. You also need to be careful if you are working with large materials such as signs, roofing panels or cladding.
Consider the location of the site. It is important to check local wind conditions and monitor the wind speed.
Be cautious when using towers in between high buildings or inside partially open structures, such as hangars, tunnels or part clad buildings. The funnelling effect here can increase the wind speed significantly.
The surrounding terrain e.g. at the top of a slope, hill, escarpment or cliff, close to estuaries or the sea, near woodland or in open country, can also increase the potential wind speeds.
If the mobile access tower is to be placed on a high structure or building, then the wind speed at the top may be considerably higher.
Where can you get information regarding good practice when using mobile towers?
The PASMA Code of Practice is the definitive stand alone reference document for good practice in the use of mobile access towers. It is available from the online shop or you can view a copy free on the PASMA App.
Where can you get PASMA training?
PASMA registered and approved training centre deliver the nationally recognised PASMA training syllabus for competency in mobile towers. Click here to find your nearest Training Centre.
Do you need an instruction manual to assemble a tower?
Quite simply – if you don’t have a copy of the current instruction manual, you cannot assemble the tower. You can find PASMA Manufacturing Members’ instruction manuals either on their websites or in our manuals library.
If you hire a tower you should be issued a copy by the hire company. When you are assembling, altering or dismantling a mobile tower:
- You must have a copy of the correct instructions with you
- You must note all of the safety information, the schedule of components and follow the step by step instructions every time and you must do this even if you are a PASMA trained operative
- Remember your PASMA training – no instruction manual means you cannot assemble the tower!
Do you need to fit stabilisers on mobile towers at 2.5m height or less?
It depends on the manufacturer’s instructions for the tower height you are building. The old 3:1 rule for the ratio of tower height to base dimension no longer works for determining the stability of a mobile tower. The base dimensions are now determined by a complex calculation in EN1004 which takes into account lots of factors. The only way you can determine if the stabilisers are required and which size of stabilisers to use, is to look it up in the manufacturer’s instructions schedule of components. Remember that you must fit stabilisers at the first opportunity in the build sequence and remove them at the end when dismantling.
Do you need to be competent to use a mobile tower to work?
There is a specific PASMA training course available for persons who will only be working from mobile towers but who are not building or dismantling, adjusting or moving them. Click here for details on the Work at Height Novice Course.
The Work at Height Regulations requires all persons working at height to be competent using the relevant equipment and they must be able to prove their competency.
When should mobile towers be inspected?
Towers must be inspected as often as is necessary to ensure safety.
PASMA recommends that on towers where it is possible to fall 2m or more you should carry out inspections after assembly or significant alteration, before use and following any event likely to have affected the towers stability or structural integrity. You should complete and issue the inspection report in accordance with the requirements of the work at Height Regulations. Re-inspect the tower as often as is necessary to ensure safety but at least every 7 days and issue a new report each time.
You do not need to re-inspect the tower if it is moved unless it was necessary to significantly alter it to make that movement or if anything happens when moving it that may have affected its safety.
A tower from which it is possible to fall a distance of less than 2m has different inspection requirements. It must be inspected after assembly, and before use; after any event likely to have affected its stability or structural integrity and at suitable intervals depending on frequency and conditions of use.
PASMA recommends the use of the PASMA Tower Inspection Record which not only gives a visual indicator of the tower’s inspection status but also, when affixed to the tower and retained on completion, satisfies the inspection requirements of the Work at Height Regulations PASMA has produced a pocket card and posters explaining the inspection requirements for mobile towers. The Inspection Records, pocket card and poster may be purchased on the online shop .
Should you use a safety harness and lanyard as fall protection when working on a mobile tower?
Both PASMA and the HSE specifically recommend that you do not use a safety harness and lanyard when working on mobile towers. If the guardrails have been correctly installed then the tower has collective fall protection so personal fall protection is not necessary.
In the event of a arrested fall on a mobile tower you are likely to cause the tower to overturn increasing the risk of injury to yourself and also to others in the vicinity.
If the tower is not high enough to complete the task is it acceptable to increase the height using the adjustable legs?
Never use the adjustable legs on a mobile tower to gain extra height. The only purpose of the adjustable legs is to level the tower on uneven or sloping surfaces. At least one adjustable leg should always be on minimum extension.
Is it acceptable to use a mobile tower without the castors or base plates or adjustable legs?
Never use a mobile tower without either the castors or base plates fitted at the base of all the uprights. Never use a tower with the base of the end frames resting on the ground, even if you have placed boards or other packing beneath. They are not designed to be used in this way.
What should you do if you do need additional height or if you need to reduce the height?
They only way to increase or decrease the height of a mobile tower is to use the correct height of end frames.
Is it acceptable to assemble a mobile tower on a slope?
That depends on lots of factors so it is not possible to give an absolute answer. Conditions on site can vary so much and only your risk assessment can determine if it is safe to assemble a tower on a slope.
It is safer to assemble a tower on a slope on base plates instead of castors. Even if the tower is on base plates you may still need to tie the tower to a supporting structure or ground anchors to prevent movement. If the slope is steep then you may need to consider digging it out locally to accommodate the base plates on a flat area.
Check if the ground surface is suitable. Loose, soft or otherwise unstable sloping ground surfaces can be particularly dangerous. Where levelling is required beyond the adjustment available from the adjustable legs, consideration should be given to offsetting or using different end frames.
Is it acceptable to climb up the outside of the tower to get to the platform?
Never climb the outside of a tower. It is not designed to be climbed in this way and it will probably overturn on top of you! Neither should you ever lean a ladder against the tower to climb up to the platform. The only way to climb or descend a mobile tower is to use the access that is provided and built-in, which means you will always be climbing inside the tower.
The access may be provided in 3 ways:
- Climbing end frames with a horizontal distance of 300mm or less- they must always be climbed in the inside
- Clip in vertical or inclined ladders – they clip on to the end frames of the tower on the inside
- Stairway or stair ladders – they are used where there is a need to carry tools and materials up and down
Should you use the smallest end frames at the top or bottom of a mobile tower?
If you are building a mobile tower using the 3T method, always use the smallest frames at the base e.g. start the tower with 2 rung frames at the base followed by 3 rungs frames and then 4 rung frames on top. This will allow you build the tower safely using the 3T method ensuring that the guardrails may be fitted at the correct heights through the build.
What rescue plans are there for towers?
Following investigation by PASMA, it was found that because there are so many variations in the circumstances that may be encountered when using mobile towers, it is not possible to give any specific guidance regarding rescue plans. These variations include; the reason for the rescue, the persons involved, the dimensions of the tower and its design, the state of build – either partial or complete, the location, the environmental conditions at the time, other local circumstances. All of these factors and more, create significant differences to the potential methods of rescue. However, you might consider a general hierarchy of measures for rescue from a tower which will apply in many cases.
- Self-help comes first i.e. the person or persons are capable of descending the tower without outside assistance
- Next is an assisted descent i.e. the person or persons are capable of descending the tower with the assistance of others.
- Last is professional rescue i.e. the person or persons are totally incapacitated and incapable of descending the tower and need to be removed from the tower by others. If the person or persons are incapacitated such that they are unable to descend the tower even with the assistance of others, then their condition is likely to be such that only the professional medical or rescue services (ambulance and/or fire service) would have sufficient knowledge and skills to effect a safe and successful rescue. It is highly likely that in such circumstance, persons without such professional medical and rescue knowledge and skills, could potentially cause further injury and/or significant risk to themselves or the person or persons in need of rescue.
Can you use a tower as a means of access to another place?
The PASMA Manufacturers Technical Committee has confirmed that a tower may be used as a means of access to another place; considering the following information and only if ALL of the following special measures are taken, together with other measures which may be identified as necessary as a result of a risk assessment as a requirement of the Work at Height Regulations.
Freestanding mobile towers designed in accordance with the product standard EN1004 are not intended for gaining access to another place i.e. transferring from the tower to another adjacent place by stepping on and off the tower.
The scope of the standard PASMA user training course covers towers in accordance with EN1004 and therefore does not cover towers which are not freestanding.
The act of transferring from a tower to another place may only occur if the tower is not freestanding and a proper risk assessment has been carried out and which can demonstrate that ALL of the following special measures will be taken together with any others that are found to be necessary as a result of a risk assessment:
- The tower must be tied with sufficient suitably strong rigid two-way ties (i.e. not ropes or straps) to a suitably strong and secure adjacent structure. Ties should be fixed to both verticals of the tower at both ends of the tower. Generally, that will require ties at least at 4m height intervals. Anchors used as a means of securing a tie to the supporting structure should be selected, installed and tested in accordance with the requirements of BS 8539.
- The tower must be built on base plates instead of castors.
- There must be no gaps between the tower and the surface you are transferring onto through which a person could fall or partially fall.
- The tower platform and the place to be accessed must be sufficiently close and vertically aligned so that there is no possibility of a fall, slip or trip when transferring from one to the other.
- Particular attention should be given to ensure that the correct guardrail heights are maintained when a person is stepping from the tower to the adjacent place or from the adjacent place to the tower.
- The safety of the person once they have transferred onto the adjacent place needs to be considered as this now becomes a place of work at height and the requirements of the Work at Height Regulations (in the UK) will apply whilst they are there.
- The strength of the adjacent place must be assessed to ensure that it is safe to step onto (i.e. not a fragile surface) and that its surface is suitable and a safe place for work and that there is adequate collective protection or other measures implemented in accordance with the requirements of the Work at Height Regulations (in the UK).
- You should never use a mobile tower as edge protection. They are not designed for this purpose even when tied to supporting structure. Edge protection should be designed and installed in accordance with BS EN 13374 Temporary edge protection systems — Product specification — Test methods.
- You should never use a mobile tower as an anchor point for personal fall protection or work positioning equipment. They are not designed for this purpose even when tied to a supporting structure.
- The Work at Height Regulations specify that the means of protection shall be removed only for the time and to the extent necessary to gain access or egress or for the performance of a particular task and shall be replaced as soon as practicable. The task shall not be performed while means of protection are removed unless effective compensatory safety measures are in place. This point should be considered carefully in a risk assessment (as a requirement of the Regulations) identifying and justifying the compensatory measures that have been implemented.
- Whilst a tower may be used as a means of access taking into consideration the points noted in 1-10 above, its use as edge protection or as an element or component of edge protection, would take it outside of the scope of both BS EN 1004, the standard for mobile towers and also BS1139 Part 6, the standard for structures outside of the scope of BS EN 1004 but utilising the components from such towers. A mobile tower is not designed for and not suitable for providing edge protection and should not be used for that function. The loads that are potentially generated in edge protection are not considered in the design standard for mobile towers (BSEN1004). Advice on edge protection and edge protection equipment is available from the Edge Protection Federation.
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