Reducing ADT Overturning Risk on Gasholder Infill Works
23 April 2018
Most contractors deploying articulated dump trucks over a period of time will have suffered the overturning of a skip during operations, often throughout the course of repetitive deposition work with competent and experienced operators.
The causes of the incidents are varied but include shifting loads, poor haul road maintenance, soft ground, driving too fast, reversing over obstructions etc., but in nearly all cases the operator could have prevented the event if they were aware that the skip was tilting at some point in the operation.
VHE pioneered trials using retro-fitted inclinometers in 2012 but were unable to get buy in from manufacturers due to their reluctance to specify safe angles of operation due to the potential influence of plant deployment, including variation in load type, distribution, quantity and working conditions.
Times have changed significantly now and there are, thankfully, numerous pre and retro fitted inclinometers offering audio and visual alarms to operators based on the chassis angle of the skip and set for both roll and pitch in both lowered and raised skip positions. VHE have recently successfully completed a holder infill project at the former Burnley gasholder site, where a standard ADT fitted with a modern inclinometer was compared against the performance of an ejector articulated dump truck, which does not require raising of the skip to deposit it’s load.
Ejector dump trucks have always been the plant of choice when dealing with low headroom challenges but are not readily considered for general contracting activities with the ejector body generally only being suitable for applications where the maximum rock/aggregate size is less than 150mm.
In the head to head challenge at Burnley, there was no difference in load haul operations, or actual tipping cycle, but the ejector truck was impressive in unloading while travelling, leaving an evenly thin spread layer, requiring less dozer effort in grading. Despite atrocious weather conditions in February and the movement of some 12,000m3 of fill, involving 800 load haul and tip cycles, there were no incidents or overturn near misses reported from either truck.
Industry records indicate that over half of the overturning incidents reported occur when the skip is either partially or fully elevated, adopting either an ejector body or standard ADT fitted with a modern inclinometer, indicating the status of the vehicle prior to initiating tipping, could eliminate at least half of these unexpected and hazardous incidents.
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