Mobile tail spar rolls over during move, now a write-off

Safety Alert Type: 
Yarding and Loading
Approximately 90 km north of Terrace, BC (km 61 on Big Cedar Mainline)
Date of Incident / Close Call: 
Company Name: 
Brinkman Forest Ltd./Coast Tsimshian Resources
Details of Incident / Close Call: 

On a logging show near Terrace, a back spar machine was walking into the setting to prepare to set-up for grapple yarding. It up-ended on a steep, unstable pitch in the setting and flipped over a number of times into the cut block below, while the operator remained inside. The operator was not injured. The machine suffered severe damage and was unrecoverable.

Incident Details and Timelines: On August 23rd, 2013, a Friday near the end of the work day, a brief logging inspection was conducted on the above mentioned logging show to check on the status of a road capping (gravelling) project.

At that time, grapple yarding operations were taking place. The terrain was relatively steep, with side slopes around 35% in the area that was being yarded. The yarder was rigged to a stump within the setting, as the boundary of the setting was bordered by an older, free-growing block of regeneration with no tail holds.

Prior to leaving the setting, the Operations Forester was having a conversation with the in-charge bush foreman. The foreman had asked if they could use their mobile tail spar along the western boundary of the setting in order to speed up productivity. The answer was yes; however, they had to construct an excavated or bladed trail through the setting for safety reasons due to the steep side slope.

On Monday, August 26th, the Operations Forester received a phone call from the contract owner in the late afternoon, that the mobile tail spar had rolled down the hill from the setting edge and flipped a few times through the regeneration, with the operator inside the cab, prior to coming to rest approximately 80-metres from the edge of the setting to where it up-ended.

When asked, the owner confirmed that the operator was uninjured, with the exception of some minor cuts and bruising etc. The operator was assessed on-site by the First Aid attendant and subsequently taken to the hospital for further examination.

A follow-up investigation was conducted early the next day. The first aid attendant pointed out where the machine had begun walking into the setting from the road edge and the approximate location of where it went over. It is alleged that the yarder operator was the only witness to the machine flipping over.

Upon walking the path of travel of the back spar machine, it became quite clear that there was no attempt made to actually construct a level “trail” for the purposes of walking the machine through the setting with secure and stable footing. The machine was walked across the stumps and logging debris at an angle that cut across the contours of the slope but in a downward direction. Upon doing so, it encountered obstacles of debris and steeper pitches of undulating terrain.

To make the situation worse, the ground beneath the logging debris was wet and soft from previous days of rain (hence the capping of the road) and there were sporadic sections along the travel path where the machine slid downwards along the hill in short, steep pitches, indicating unstable terrain. The travel path of the machine was clearly evident within the block and showed exposed, silty clay material, confirming soft ground at the time (see photos in attached pdf).

Just prior to the location where the machine up-ended, there were a few chunks of logs and debris pointing up and down the slope at a steep angle across the travel path of the machine. It was concluded that failure to remove the coarse debris and construct a flat, level work area caused the up-ending of the machine and subsequent rollover(s).

Investigation Findings - Incident Causes:

• Failure to follow Safe Work Procedures by ensuring that the path of the machine is clear of logs and other obstacles and that traction is adequate. Construction of a flat, level trail for solid machine footing across steep ground did not take place.

• Lack of recognition of / or disregard for unsafe act. • Unstable, undulating terrain and soft, wet ground (weather).

• Improper loading of machinery onto unstable debris.

Learnings and Suggestions: 

• Safe work practices were established for this phase of the operation but not followed. This will be discussed with crew at tailgate meetings. In addition, it was determined that the SWP’s were not complete based on this incident and required revision.

• The Safe Work Practices for Mobile Grapple Yarder Operations only specified that “traction should be adequate” and that “the path of the machine should be clear of logs and other obstacles”. It does not specify that an actual “flat trail” be constructed to safely maneuver machinery across a slope, as this was implied. This will need to be added to the SWP’s as it was a contributing factor to the incident. Even if the operator had ensured that the path of the machine was clear of logs and other obstacles, it is unlikely that the incident would have been prevented since there is evidence of the machine sliding on steep, unstable, wet terrain.

• Revise SWP’s and discuss with crew at tailgate meetings. It is an acceptable practice to build and utilize trails on steeper terrain if it will create a safer working environment for machinery.

For more information on this submitted alert: 

For more information contact: Benjamin R. Korving, RPF Operations Forester, Brinkman Forest Ltd. / Coast Tsimshian Resources Ben_Korving@brinkman.ca


File attachments
Mobile tail spar rolls over during move, now a write-off.pdf
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