Case studies: Treework accidents

A 28 year old self-employed tree surgeon was found dead in a tree with severe laceration to his neck.

He was in the process of pruning a multi-stemmed willow tree in preparation for felling it. There are no eye witnesses but it is assumed that the chainsaw kicked back causing a severe laceration to his neck. He died from his injuries almost instantly.

Working at height with a chainsaw is extremely high risk and those doing this type of work should be fully trained and competent to do the job. The equipment used to work off ground should be suitable for this use.

Find out how to prevent this type of accident

• Chainsaws at work INDG 317
• Top-handled chainsaws AFAG 308

A 68-year old self-employed, experienced, and qualified forester was working alone when it is thought that he fell and died from serious head injuries

A 68-year old self-employed forester was working alone when it is thought that he fell and died from serious head injuries. There were no witnesses. He had been subcontracted to assist in the felling of standing hardwood including the tidying up and stacking of timber for removal. The site was tidy and well organised and it is assumed that he slipped, tripped, stumbled or passed-out falling onto a tree stump, which caused his injuries. He was later discovered by the forestry works manager who had been contacted by a family member concerned about his whereabouts.

How to prevent this type of accident

Eliminating the risk from slips and trips in forestry is not possible but does not mean that you can't do things to reduce the chances of an accident happening. You should keep your work area as clear as practicable, particularly when working with chainsaws or other potentially dangerous equipment, wear the right type of footwear replacing it when worn, and pay careful attention to where you're walking, particularly in difficult terrain. These precautions are just a few examples of the small measures that can be taken to significantly reduce the chance of serious injury.

Many people working in the forestry industry spend part or all of their day working alone, or working at some distance from others. If you employ people who work alone then you should have reliable procedures for ensuring that you know where they are, what they are doing and that you can keep in touch with them. Your procedures should not rely on assumptions, for example you should not assume that someone working alone in a forest has left it at the end of the day, you should have an arrangement to confirm that they have.

Find out more:

INDG73: Working alone - Health and safety guidance on the risks of lone working

A 26-year-old man was pulled out of a tree when his climbing strop broke

It seems the climbing rope became entangled and took the weight of the falling tree. He had climbed up the section to be felled to attach a 'pulling rope' before descending to the point at which he intended to cut though the last section of the tree. Whilst felling a large vertical timber section (with pulling rope assistance from work colleagues on the ground), it fell awkwardly dragging him from the tree, causing fatal injuries.

More guidance on Working at height.

A 59-year-old employee was run over by a forestry forwarder

The deceased and his colleagues were attempting to re-start a forwarder which had developed a mechanical fault while on a step slope. After carrying out a repair, while standing on the tracks of the vehicle he leaned into the cab to start the engine. For some reason the forwarder suddenly moved forward, throwing him under the wheels of the forwarder and crushing him to death. His colleagues were thrown clear.

Never attempt to start a machine, other than from the driving position

There have been many serious incidents involving vehicles at the site of tree work. Vehicle operators are particularly at risk during maintenance.

Work should not be carried out on or under a machine or whilst a machine is running or the keys in the ignition and controls engaged. When carrying our maintenance, always follow Safe Stop:

• handbrake on
• controls neutral
• engine off
• remove key

Do not attempt to start a vehicle other than from the driving position, from where the operator is able to control the vehicle.

Maintenance must be carried out in accordance with the manufacturer's handbook which should be available.

All operators should be suitably and sufficiently trained in order to undertake tree felling work and the operation of forestry machinery.

A 65-year-old self-employed director was electrocuted by an Overhead Power Line (OHPL)

The deceased was driving a lorry-mounted timber crane along a forest track when the boom of the crane touched an OHPL and caught fire. He was electrocuted as he dismounted the lorry cab. It would appear that the crane boom was not fully folded and stowed in the transport position while travelling and came into contact with the OHPL.

Work should be planned to minimise the risk of contact with OHPLs

Make sure you have a map of the routes of the lines (available from your Distribution Network Operator) and that visiting workers such as contractors have copies (include details of OHPLs in contracts).

Organise operations within the worksite to minimise the need for vehicles to pass close to or beneath OHPLs.

When travelling to and from worksites machine booms and attachments should be lowered to a safe height.

Erect goalposts within and between worksites to ensure vehicles do not contact OHPLs.

What to do if you come into contact with an OHPL

• If part of a vehicle or load is in contact with an OHPL, the operator should remain in the cab and inform the DNO immediately (display the number in the cab and keep it on your mobile phone).
• Keep others away.
• Try to drive clear or lower the parts of the machine in contact with the OHPL. If this is not possible JUMP CLEAR – do not dismount by climbing down the steps. Do not return to the vehicle until the owner of the line has confirmed that it has been de-energised and made safe.
• Never try to disentangle equipment until the DNO has confirmed that the OHPL  has been de-energised and made safe.
• WARNING: Contact with an OHPL may cause the power supply to 'trip out' temporarily and it may be reconnected and re-energised automatically, without warning. Therefore do not assume a line is de-energised until it has been confirmed with the DNO.

Find out how to prevent this type of accident

Working near power lines and cables

More case studies are available to view at the National Archive website.

• A 'sink cut' is a triangular cut made near to the base of the trunk in the side of the tree that the tree is intended to fall. It should be made at an angle of approximately 45 degrees.
• A 'felling cut' is the horizontal cut made into the rear of the tree, just above and towards the sink cut. The felling cut should stop before it meets the sink cut to create a hinge.
• The falling action of the tree is controlled because the portion of the tree that has not been cut through creates what is called a 'hinge'. This allows the felling direction and the rate of the fall to be controlled.
• 'Wedges' are one of the tools used by forestry workers and the use of them to free a jammed chainsaw is not uncommon.
• A 'bench' is the term used for the felling one tree into a horizontal position on the ground so that the next tree can be felled to land on top of it. The technique is used to make the task of snedding easier.
• 'Snedding' refers to the removal of branches from the trunk of a felled tree. This is carried out after a tree has been felled and is carried out with a chainsaw.
• The 'danger zone' is an area to the front and rear of a tree, where the tree is most likely to fall either during or after the sink and felling cuts have been made. Appendix 1 (AFAG302 – Basic chainsaw felling and manual takedown) illustrates this at Figure 1.