Instances of Numeracy in Recycling and Refuse Collection.

1
Instances of Numeracy in Recycling and Refuse
Collection.
2
Categories

• Spatial Awareness
• Counting
• Estimating
• Compliance

3
Spatial Awareness
Using Mirrors

• Driving dual controlled trucks, having a reverse
  sense of mirror usage is critical.
• Right hand side small mirror is used for checking
  roadside hazards.
• Left hand side mirror is for lining up arm with
  bin
• They still need to check over their left shoulder
  for bins that are not lined up.

4
Spatial Awareness
Best position of arm

• Left hand mirror is positioned so that midpoint
  of arm is visible, for quicker pick up.
• Bin is grabbed halfway up for effective lifting
  and preventing it from falling into hopper, as
  bins are tapered at bottom.

5
Spatial Awareness
Hazards that slow the rate of pick up

• Older suburbs with less off-street parking, they
  can collect only 80-90 bins in an hour because
  they have to get out of the truck to move the
  bins between parked cars.
• In suburbs with more off-street parking, drivers
  can pick up between 200 - 300 bins in the same
  time.

6
Spatial Awareness
Other Hazards

• Impatient drivers
• Tree branches on kerbsides
• Narrow streets esp. with trees
• Tradesmen often park anywhere, lacking
  consideration for bin collectors, who then have
  to get out of their trucks to move bins.

7
Spatial Awareness
Cul de Sac positioning

• Sometimes they must drive onto next pavement to
  line up with bin of previous house, which can be
  hazardous if many tree branches get in the way.
• One proficient driver used his Exit not
  Approach strategy, driving as if exiting the
  cul-de-sac, then backing up to line up more
  closely to bins, then picking up as he drives
  out.

8
Spatial Awareness
Where do you restart once you return from the
transfer station?

• If I reach the weight limit while Im in the
  middle of a street, I choose a house next to a
  clearing to stop at, as a landmark.
• I stop at a corner house and leave the lid open.
• Leave the bin at a slight angle, compared with
  the rest.

9
Counting
How do you check whether youve collected all the
bins in the area?

• We have a starting point and a finishing point,
  one street at a time.
• Bin counter does the counting.
• Sometimes people accuse us of not collecting
  their bin, but we generally know the run very
  well.

10
Counting
Do you have an idea how many bins there are in
any one street?

• As you get used to the area, you have an idea of
  how many bins there are in a street.
• You also get to know which bins will be out and
  when.

11
Counting
What does the bin counter tell you?

• Number of bins
• Arm hours (maintenance)
• Weight of load

12
Counting
Most number of bins collected in an hour?

• 240 for heavy areas and 300 for light areas, if
  there are no distractions or emergencies.
• Beginning drivers collect about 120/hr, average
  drivers 300/hr.

13
Counting
Are there any counting skills from your culture
or past experience that help you in this job?

• Did maths as part of engineering course and
  soccer skills.
• Health and safety representative in a previous
  job skills help me with thinking safety first.
• Logistics from armed forces experience.

14
Counting
Do bin numbers change over time in an area?

• Yes, there is one area with large sections that
  has been sub-divided a lot in the last two years,
  since weve started.
• The number of bins have gone up
• from 160 to over 240.
• New sub-divisions being developed with 5000 to
  7000 homes will need new routes on maps.

15
Estimation Spatial Sensing

• See overfull bins, so square them up on the
  lift (to avoid spillage)
• Accommodate refuse truck drivers and look for
  passing areas along the road
• Feels heavier if the arms move slowly or strain
  so probably concrete or dirt in there
• Feel heavier when activating the control stick

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• Wait until level areas along roads for accurate
  readings of scales
• Returning bins onto sloping verges, need to be
  stable
• Deciding on route e.g. dependent on remaining
  bins to get as close to (the scheduled) count of
  300
• You can sense when youre getting full from the
  hopper inside camera (refuse trucks dont have
  weight limitations)

17
Estimation Timing

• December bin numbers, weights are generally up
  more barbecues, etc so consistently 4 loads, but
  in winter bins go out less, so maybe three loads.
• School holidays - less traffic on the road, so
  shorter peak traffic hours
• Contractors fill diesel when required since they
  pay for it
• Employed drivers fill each afternoon
• Stop-start motion tough on brakes. Tyres last
  about three months

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• Before 7 am you get a good flow but if between 7
  to 8 oclock add 10, 15 to 20 minutes
• Always estimating how far they can go / load up
  before returning /unloading
• Arms on refuse trucks go up and down about 1400
  times a day, so the belts do wear down.
• Can go to streets and predict ten minutes
  collecting here, half an hour there, etc . . .

19
Estimation Measuring

• 2½ to 3 metres reach to the side
• Have about 4 tonnes (3.96t) worth of recycling
  capacity
• Hill readings generally inaccurate
• Trucks about 10,070kg when empty. Add drivers
  weight, and a full tank of diesel, full weight
  will be 10,260kg if diesel is a quarter full, it
  is 10,200kg

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• Start at 5.30 am, first pick up at six. Try to
  work outside rush hours
• When truck is two-thirds full, we stop regularly
  and check. Some light days we dont use scales,
  because total 9½ t on, anticipate only 750 bins
• Refuse bins are 120 litre capacity but some
  houses only need 80L
• When cars park on both sides of narrow roads,
  truck drives through with margins of 2-4 cm each
  side

21
Estimation Number

• In May this run was 965 bins so a fourth load
  was needed for that. In July the same run was
  841 bins so the difference of 120-130 bins means
  we could do it in 3 lots of 270-280.
• Planning the route out of here, depends on a load
  of around 270 to 280 bins.
• That day, expecting less weight and his
  anticipated 841 total, he knew from experience
  there were another 3 - 4 bins left to complete
  the second load of 275, so a third load would
  finish the run.

22
Estimation Locality

• Socio-economic nature of an area has a lot to do
  with bin weights.
• Operators find lower income housing areas, load
  weights are a lot higher.
• However, some higher income housing areas
  sometimes have heavier bins because the
  periodical magazines in bins use heavy paper
  probably heavier than anything else they
  regularly collect.

23
Compliance

• Too much weight results in a penalty going across
  the scale
• Penalties are on a graduated scale based on
  compaction ratio (of 180). Related to the cubic
  space in the back of the truck (22.5 or 25 or 29
  m³). If you go over that e.g. over 4.32t or 320
  kg contractors get individual fines while
  employed drivers lose their company its bonus.