Archive for the ‘Power Line vegetation management’ Category

Arboriculture Canada delivers training for Maritime College of Forest Technology

Monday, July 25th, 2016

When the Maritime College of Forest Technology (MCFT) first started designing the Utility Arborist Program (UAP), they approached Arboriculture Canada Training and Education Ltd.  (ACTE).  ACTE will be providing 160 hours of theoretical and hand’s on practical instruction to UAP students.  See details here:  http://utilityarborist.ca/blog/

The Key Notch

Tuesday, January 13th, 2015

In some cases, trees are hung or snagged because they have been uprooted.  In these situations determining where the loads are concentrated can be difficult, and often the root plate is a stronger force to be considered than the hung tree itself.  Gravity is always acting on mass and never takes a day off.

This uncertain circumstance presents challenges that must be considered when attempting to cut the tree free from obstacles.  The main focus of the cuts I have described in my past two articles (mis-match cut and controlled hinge release) has been to allow the cutter to be at a safe distance when the final cut is released and the tree falls and is cleared from its snagged position.  The use of rope and mechanical advantage allows cuts to be released in a controlled manner and the tree to be pulled from a safe working distance while trying to free it.  For safety’s sake always plan, prepare and use an escape route.  Avoid cutting and releasing a snagged tree while standing next to it by creating a barrier using distance and rope.  The further away you are from the snagged tree, the better (within reason), but a good rule of thumb is to be a distance away that is equal to the height of the snagged tree.

The key notch is a technique for freeing a hung or snagged tree that releases all holding wood while maintaining control until a pull force is applied.  It takes some time to cut and works well on trees that are hung and snagged where the compression and tension forces are very difficult to identify, such as with uprooted trees.

First evaluate and determine the zones most likely under compression and tension.  In the case of an uprooted tree, the compression and tension zones can be exactly opposite that of a tree in the same hung or snagged position that is not uprooted.  The techniques of the key notch will work the same for either situation.  This is why it works well for trees where it is difficult to determine how much force the root plate is applying.

The key notch is made by making five cuts into the trunk; the first three cuts utilize the bore cut technique, cutting through the trunk and forming a tongue and groove – or ‘key’.  The tongue and side of the groove should be of equal size or thickness.  This is determined by dividing the trunk diameter into three equal parts.  In order to properly form the key notch, it is necessary that the trunk be at least three times the diameter of your chainsaw bar width.

key notchBefore making the final two cuts, wedges are installed to prevent saw bind and pinch.  The wedges are placed under the tongue on both sides of the trunk and wedges can also be inserted into the sides of the key as well.  This requires several wedges, but a minimum of two will often work.  The fourth cut is made in the compression zone and the final cut should be placed in the area of the trunk that is determined to be under tension.  By releasing a load in tension the kerf should open and allow the key notch to be completed without any bar pinching.  KeyNotch with wedges1blog

KeyNotch with Mechanical Advantageblog

Using mechanical advantage to pull the the snagged tree free.

Once the cuts are completed the worker should retreat to a safe working distance and pull the snagged tree out of the key, using a pre-installed pull line.  Pulling the tree out of the key may require more force than one person can apply and that is where mechanical advantage is incorporated into the pull.

It is my intention in writing these articles and sharing techniques, to add tools and techniques to the mental toolboxes of workers who use chainsaws to cut trees that are hung and snagged during or after storm events.  I realize that there are many different tools and techniques and I always encourage workers to stick with ones that have worked well for you.  I also equally encourage everyone to always keep an open mind and give new techniques a chance and a try.  See if they work for you, and when they do you have another tool for the toolbox!

Arboriculture Canada delivers Utility Tree Trimmer and Worker Training in Alberta – March, 2013

Thursday, June 6th, 2013

This March saw the first off campus delivery of the Utility Tree Worker (UTW)/Utility Tree Trimmer (UTT) training program in Alberta.  The Industrial Vegetation Management Association of Alberta (IVMAA) oversees the training program and certification of the provincially recognized certification. The UTW/UTT certification, is an Alberta provincially recognized certification that is mandatory for all persons who perform vegetation maintenance around energized power lines and ground work around energized power lines. It is also recognized by Saskatchewan and Manitoba through IVMA ManSask.   Before candidates can apply for this certification, they must take the UTW/UTT training program as this is a mandatory course required by all persons seeking to receive their UTW/UTT certification.

The IVMAA is the only recognized organization that can issue these provincially recognized certifications for successful UTW/UTT graduates. Successful candidates must have completed this training program and also accumulate 1200 hours working in proximity to energized electrical equipment, and these hours must be logged and verified in a log book by an already accredited UTW/UTT. The difference between a UTW and a UTT is that a UTT has to log a minimum of 600 hours working in proximity to energized electrical equipment from an aerial position.

The training component has been and continues to be traditionally delivered by Olds College in Olds, AB.   Arboriculture Canada has been getting requests for many years from customers who would like to get the UTW/UTT training but are unable to send their people away for two weeks or who missed the window when the course was offered at the college and are unable to wait until the next offer.

Arboriculture Canada delivers training components in their regular courses offerings to customers across Canada that is also part of the UTW training program and therefore has the resources to develop course content and materials for a Utility Tree Worker Training program. ArborCanada made a request through application to the IVMAA seeking recognized equivalence to the IVMAA UTW/UTT course.

Through a process of communications and meetings, Arboriculture Canada’s program was granted equivalency and a successful delivery of the program was completed in early March at an off campus location. This program was the culmination of many years of hard work, meetings and passing stringent requirements and in the end it was the first time since the beginning of the IVMAA UTW/UTT certification program that it was delivered off campus and the first time a private training company has delivered the course.  Arboriculture Canada’s course is stringent and broad in scope and combined with the electrical training it encompasses 13 days of training.

The group that received the training in March of 2013 was the East Prairie Metis Settlement. The Metis are first nation people who started families with the white settlers in the 1800’s.  There are over 500 thousand Metis in Canada today. The training took place at their site and location, near High Prairie Alberta, where the Great Plains and the boreal forest converge – a land of lakes, rivers, aspen, spruce and pine and the theoretical in-class learning was complimented by tying knots by the fire, climbing, rigging and other practical hands on time in the field.

Congratulations to the successful graduates of the first off campus Utility Tree Worker and Utility Tree Trimmer training and qualification program.

 


Controlled Hinge Release – releasing lodged or hung up trees.

Sunday, May 8th, 2011

In my last article I shared a technique for safely releasing lodged or hung up trees.  I am going to expand on this concept in this article.

One disadvantage of the mis-match cut is that in some cases, the vertical wood fibre lamination may release before the saw operator is at a safe distance away.  It is a rare occurrence, but it can happen and is an example of why alternative techniques are always good to have in the mental toolbox.

The controlled hinge release is another technique for releasing hung or snagged trees that can offer some additional control when cutting these types of trees.

Controlled hinge release techniques at work.

The controlled release hinge technique is employs the use of a notch and also requires the hinge to be established using a bore cut.  The notch and hinge are set before the final back cut is made and optimizes safety by using a mis-matched back cut and a pull line to release the tree when the operator is ready and clear of the danger zone.

An open face notch is cut in the opposite side of where the pull line is installed. This way when the tree is pulled, the notch closes and the tree hinges towards the pull line. The placement of the notch should not only consider the pull line direction but also the side that best facilitates the dislodging of the snag or hung tree.

Preparing to by-pass the strap.

The bore cut establishes the hinge which should be made thinner than normal when dealing with a standing tree.  Instead of the standard 10% to 7% of diameter, a maximum of 5% to 3% should be used. This is due to the lack of bending moment that exists in hung or snagged tree scenarios.  A limitation of this method is that it is best suited for large enough diameter tree where there is enough wood behind the hinge to allow for the bore cut to be made and in situations where the butt of the tree is not attached to the roots or dug into the ground.

First attach a pull line to the tree and install any mechanical advantage needed to pull the tree. Once the notch and hinge are cut, you will have the small portion of wood left uncut at the back of the tree – commonly called the ‘strap’.  The final step is to place a by-pass or mis-match cut just below the bore cut and cut far enough so that this kerf passes the kerf above, creating a mis-matched strap. This will hold or control the release of the tree until a load is applied to the pull line.

The strap releases and the tree will fold or ’walk’ in the direction of the pull line when the tree is pulled.  Often this action is enough to dislodge the hung tree or snag.  If it does not, the line is moved up and the technique is repeated. The repeated cuts move the snag or hung tree in a lateral direction, encouraging it to dislodge and keeping the snag from becoming more vertical where it is likely to fall unpredictably when it dislodges. The controlled release hinge maximizes cutter control and safety.

Bore cutting the back cut of the controlled hinge release.
Safe working distance.
Using mechanical advantage to dislodge a snag.

An article is no substitute for hands on training and this article is intended to stimulate thought.  I trust my description along with the photo’s can help you to understand this very effective technique for freeing hung or snagged trees.

Too often a variation of this technique is used with a conventional back-cut, where the notch is cut in the upper side of the snag and the hinge is formed with the cutter standing right beside the tree and a very quick and abrupt jump is made in an attempt to escape as the tree releases and hinges.  Control is not part of this technique and can result in the cutter being struck or pinned by the butt of the tree.  This technique also moves the tree closer to the snagged or hung obstacle, causing the tree after frequent attempts to become more and more vertical resulting in a very large and dangerous drop zone.

It is a known fact that 90% of all tree cutting accidents occur within 5 feet of where the final cut is made, within 15 seconds of the tree beginning to fall or hinge. This is called the 5-15-90 rule. It stands to reason that if the tree can be released at a distance greater than five feet and before falling or hinging action begins that the likelihood of being injured is reduced by 90%. It is with this thought in mind that the controlled release hinge is utilized.

In my next article I plan to share another technique which is well suited for scenarios where an uprooted tree is hung or snagged, or where the butt of a snagged or hung tree is dug deep into the ground.

Dwayne Neustaeter

Vegetation Management – Using the Mis-Match Cut to Free Hung or Snagged Trees on Power lines.

Saturday, December 4th, 2010

During and following severe storm events there is often a need to cut trees, remove large limbs and other debris off the power lines in order to begin the power restoration process. This work is often performed during the storm event or in conditions that are challenging due to weather, darkness and other factors. It is a known fact that working with a chainsaw is one of the most dangerous work procedures any worker can face, compound this with inclement weather and darkness and there is a potential for serious worker injury to occur.   

 Often the workers called on to perform these tasks are power linemen who may have received little specialized training in the skills needed to ensure their safety while working in these situations. Some time ago, while I was providing some basic chainsaw training for a utility client, I asked the student/lineman when they most likely used a chainsaw. Their answer was during or after storms to clear the lines in order to restore the power service. I knew the training we were there to provide did not cover this aspect of tree cutting and as a result, we developed and delivered a specialized curriculum to help lineman meet these challenges safely and efficiently.   

 Since then we have refined and developed techniques that help linemen cut trees and remove branches and debris from power lines. The most common risk that lineman take when cutting trees from the line is that they are typically standing too close to the cut, the line and the tree part when it is released. The review of logging accidents and fatalities indicate that when a cutter is within five feet of where the cutting and release takes place 90% of the accidents and fatalities occur.   

 It was with this in mind that we teach linemen how to use cutting techniques that allow the worker to be at a safe distance away when branches or trees are released. We can teach these techniques by using simple equipment already available and familiar to lineman. It is important that a lineman understand the severity of risk that exists when they are cutting trees hung on power systems.  Linemen already clearly understand the threat of electrocution.  It is the reactive forces of the chainsaw and trees that is most often not a part of the curriculum of most utility apprenticeship programs.   

 Training that teaches the correct techniques for basic tree cutting is necessary for linemen who cut trees on or near the power system during or after storm events in order to support and document due diligence for their occupational health and safety protocols. Documented training and qualification in techniques that provide options that can accommodate a variety of situations or scenarios addresses the problem and ensures diligence. In many cases linemen perform this work based on trial and error and the younger workers rely heavily and often solely on the experience of the seasoned journeyman lineman who often have learned the lessons the hard way. This leaves everyone exposed and at risk for a preventable and negligent inevitability.  If you have linemen or workers who perform these tasks, be sure that documentation of training and records exist that show your organization addresses the specialty situations posed by trees, tops or large limbs hung on the power lines.   

 Here is an example of a very simple technique that allows a cutter to be at a safer distant from a cut when it is released. In other words, it allows the cutter to be already away and in an escape route.  

Mis-match cut

 The mis-match cut or by-pass is a very simple and effective two-cut process that employs wood fibre strength to the cutters advantage. In addition by employing the use of a hand line, a common tool linemen use regularly, any lineman can cut a snagged or hung tree part and release it using the hand line from a safe working distance. Often one or two cuts will free the problem from the line allowing power restoration to commence.  

Making a mis-match cut

 This technique places the cuts in a staggered manner with the lowest of the cuts made in the direction of the intended pull. Attach the hand line to the tree part prior to commencing cutting. The cuts are made just pass half or through the mid way point of the diameter of the tree or branch. It is very important that the cuts are perpendicular to the force of gravity acting on the wood. Equally important is that both cuts bypass each other. The laminated strength of the wood fibres is strong enough to resist breaking, allowing time for the cutter to retreat and pull the piece free with the hand line at a safe distance. The pull of the hand line causes the kerf to close and the vertical wood fibre to release. 

If a mis-match / by-pass cut is unable to be released by pulling, the next option is to insert wedges into both kerfs and drive these wedges alternately until a small crack appears or any cracking or fracturing sound is heard.  It is very important that as soon as a crack is seen or heard that you stop driving the wedges and proceed to a safe distance.  In most cases pulling on the line at this point will release the snag.  Repeat the process as necessary.  

 The primary advantage of using this simple technique is that it allows the cutter to release the tree part at a safe working distance from falling debris, loaded power lines, flying branches or while holding a running chainsaw.  This technique is one of the most popular and is appreciated by linemen who have performed the work I have been describing. They recognize and appreciate the safety advantage this method provides and comment on how they wish they had learned it earlier in their careers. A short  2-3 day course can provide simple and effective work procedures that will improve linemen health and welfare while cutting trees from power lines during or after storm events in order to restore power to customers efficiently and safely. 

  The work many utility workers perform during or after storm events is not basic or ordinary. When called upon they enter an arena of risk seldom faced by many seasoned chainsaw workers – it makes sense that they receive training and education that provides the skills needed to face this dangerous work environment. 

  Dwayne Neustaeter