Tracking a 360° Along a Cambered Haul Road
You are operating a 22-tonne tracked 360° excavator with a 2.9 m dipper and a 1.2 m³ bucket, moving from a stockpile to a new cut 400 m away along a compacted site haul road. The road runs along a clay embankment with a 1-in-8 cross-fall toward an open drainage channel on the left. The surface is damp from overnight rain and the first 60 m is rutted to about 250 mm deep. The excavator is in travel mode with the bucket carried low and the dozer blade fitted at the front. Your banksman is 80 m behind you, out of sight around a bend, and radio contact is intermittent. A tipper truck is loading at the far end and will be reversing out as you arrive.
1. Describe how you would plan and carry out the travel, including the direction of travel, blade position and speed, and justify each choice.
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Direction and blade: Travel with the dozer blade leading (blade forward, over the idler end) so the blade can act as a brake and a grade-control tool on the descent. On a cross-fall toward the drainage channel, keep the blade on the low side and set it lightly in contact with the ground so any slide is checked. The bucket stays low and trailing, roughly 300–400 mm above ground, to keep the centre of gravity low and give a second point of contact.
Route choice: The 60 m of 250 mm ruts are a tip-over and track-damage risk on a cross-fall - do not straddle them diagonally. Either track slowly along the high side of the camber, or stop and grade the ruts with the blade before proceeding.
Speed and control: Low travel speed, steady, no simultaneous tracking and slew on the camber. Cross the camber square-on rather than turning on it.
Justification: The machine's stability envelope is reduced by the cross-fall, the wet clay and the raised centre of gravity of a loaded bucket; blade-leading travel converts a potential slide into a controlled brake, and low bucket carriage limits the consequences of any track slip.
2. The radio link to the banksman is intermittent and a truck will be reversing at the destination. What do you do, and why?
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Do not travel blind. Options in order of preference:
- Re-establish communication - wait until the banksman can see you and confirm by radio, or move the banksman to a position with line of sight to the bend and the loading area.
- Stop and reassess - if communication cannot be restored, halt the machine in a safe, level position off the camber and dismount to coordinate with the banksman and the truck driver face to face.
- Segregate - agree a hold point with the truck driver (e.g. truck holds at the loading area until you are parked and the operator has signalled).
Why: A reversing tipper and a tracked excavator on a bend with no reliable communication is a classic struck-by/pedestrian scenario. The banksman's role is only effective if he can see and be seen/heard; an intermittent radio is not a control. The operator must not proceed on assumption - the safe system of work depends on positive confirmation, not on hope.