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Effect of Satellite Vehicle Type. Three of the four makes studied
were capable of coping with all types of route conditions. The
fourth did not have enough power to climb hills and steep driveways at
a reasonable speed. The expertise and collection habits of the
individual operator far outweighed any slight advantage one particular
vehicle might have had.
Effect of Terrain. It took about 15 percent less time to complete
one load in flat areas than it did to service similar homes on extremely
hilly terrain. In part, this was due to the fact that the vehicles had to
travel at reduced speeds when negotiating steep driveways and roads.
Homes in extremely hilly areas were usually high-income types and
sat farther from the street than houses on flat terrain; the average
distance traveled up driveways was 100 feet as compared to the
overall average of 80. In addition, operators in hilly areas had to
walk 20 feet from their vehicles to storage locations, 10 more than on
flat terrain.
Effect of Item Types Collected. Excessively heavy containers
without handles required more time to carry from the storage point
and unload into the satellite vehicle. When, for example, a 55-gallon
drum was used instead of a standard-size container, the pickup time
increased by 35 percent. Since such receptacles are cumbersome and
difficult to empty, they are potentially dangerous to both the home-
owner and collector. They should, therefore, be barred from use in
all communities.
Less collection time was required for such miscellaneous items as
paper or plastic bags and cardboard boxes, because no container had
to be returned to the storage point.
Effect of Weather. Since all the studies were made in summer,
the winter capabilities of the satellite vehicles could not be evaluated.
The agencies reported, however, that no difficulties arose until at
least two inches of snow were on the ground. It appears that ice or
larger accumulations of snow could impede efficiency to the point that
a walking collector would be equally or more effective.
In areas experiencing high temperatures and humidities, the
satellite vehicle offers relief from fatigue and heat exhaustion by
reducing the amount of walking that would otherwise be required.
Packer Truck Driver Activities. All 12 packer drivers spent less
than 20 percent of their time driving, and the balance was available
for collecting or helping the satellite vehicle operator (Table 4).
Effectively assisting two of the latter personnel should take about 20
percent of the packer driver's time. Of the remaining 60 percent, 45
should be devoted to collection, 10 to waiting at the truck, and 5 on
"other" time. Each additional crew member would require 10 percent
of the driver's time, and this would correspondingly reduce his
collection activities.
-------
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All the packer truck drivers in the commercial crews did some
collecting, at an average of 59 percent of the time available. The
amount of time spent by municipal drivers on this activity was
negligible.
Annual Cost Per Dwelling Unit
The homeowner judges the effectiveness of any residential waste
collection system by the cost to him of the particular level of
service he receives. As service increases, the price must go up
correspondingly. Backyard service costs more than curbside, and
twice-a-week pickup is more expensive than once-a-week. Within a
backyard system, to collect at a house 200 feet from the street takes
extra time and costs more than pickup at a similar dwelling only 100
feet back. If one house has three items to be collected and another
has only two, the former will cost more to service even if all other
things are equal.
The actual annual collection cost per dwelling unit for the average
conditions observed in each study site ranged from $11.00 to $46.00
(Table 5). These costs cannot be compared, since they occurred
under distinctively different sets of conditions. Average collection
costs can be calculated only for dwelling units with identical
characteristics, service levels, and crew costs.
Effects of Collection Frequency. For once-a-week collection, the
average annual cost per dwelling under standard conditions was
$19.00, and for twice-a-week pickup it was $28.50 (Table 6). The
first method was, therefore, about 33 percent less expensive.
TABLE 5
ESTIMATED COSTS OF RESIDENTIAL SOLID WASTE COLLECTION USING
SATELLITE VEHICLES, UNDER ACTUAL COMMUNITY CONDITIONS
Cost per dwelling unit
Collection
Study site frequency Per Per Per
per week collection week year
Atlanta, Georgia
(Trash Taxi) . . 2 $0.32 $0.62 $33.50
(Trashmobile) ... 2 0.22 0.44 21.50
Columbia, South Carolina 2 0.33 0.66 31.50
Knoxville, Tennessee . 1 0.20 0.20 11.00
Medford, Oregon . 2 0.25 0.50 25.50
Pasadena, California
(Hilly) . . . . 1 0.88 0.88 46.00
(Flat) . . 1 0.57 0.57 28.50
Waukesha County, Wisconsin 1 0.33 0.33 17.00
10
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Effects of Collection Agency on Costs. Private collection com-
panies averaged $15.00 per dwelling a year for once-a-week service,
while public agencies averaged $23.00. The figures for twice-a-week
pickup were $22.50 and $34.50, respectively (Table 6).
The 53 percent lower cost achieved by the private agencies was
due solely to higher crew efficiency (dwelling units serviced per
hour). This was attained because the private packer truck drivers also
collected wastes and because the commercial vehicle operators were
slightly faster than public operators.
Operational Recommendations
Satellite Vehicles. Equipment should be provided that facilitates
transferring the waste to the packer truck with a minimum amount
of spillage. Rubber or canvas flaps attached to the rear lip of the
satellite's hopper and welded metal wings on the sides of the hopper
at the rear can ease the flow of wastes into the packer's hopper.
A strict preventive maintenance program should be enforced to
minimize mechanical failures and to extend the useful life of the
vehicles. This is necessary because they are of lightweight construc-
tion and have small engines.
The vehicles should not be loaded above the top of the hopper.
Overloading leads to waste being spilled while the vehicle is enroute to
the packer and also extends unloading time. Driving speed should
be slow enough to keep waste from blowing out of the hopper.
TABLE 6
COST ESTIMATES FOR SATELLITE VEHICLE WASTE COLLECTION SERVICE,
IDENTICAL CONDITIONS BEING ASSUMED
Cost per dwelling unit per year
Study site
Once weekly collection Twice weekly collection
Atlanta, Georgia
(Trash Taxi)
(Trashmobile)
Columbia, South Carolina
Knoxville, Tennessee
Medford, Oregon
Pasadena, California
Waukesha County, Wisconsin
Average for all sites
Average for private agencies
Average for public agencies
$23.50
22.50
27.00
14.50
16.00
19.50
15.00
19.00
15 00
23.00
$38.50
30.00
41.00
22.50
22.50
28.50
23.00
28.50
22.50
34.50
11
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Safety of the operator should be a prime consideration. Visible
turning signals, large rearview mirrors, safety reflectors, and extra
taillights should be standard equipment.
Packer Trucks. To realize maximum operating efficiency, it is
extremely important to select an appropriate packer truck to work in
conjunction with the satellite vehicles. It should have a hopper that
can hold at least 2 cubic yards, thus enabling it to accommodate
a satellite vehicle load in one compaction cycle. It may be necessary
to make minor equipment modifications so that maximum coordination
is provided between the satellite's hopper and the packer blade
during unloading. This would speed up the process and minimize
waste spillage.
Packer truck drivers should be able to contact their central office
or garage via radio; in this way, collectors can be informed of missed
or extra pickups, and vehicle downtime can be held to a minimum.
Crew Coordination. Achieving optimum efficiency depends heavily
on the coordination of activities by the satellite vehicle operators
and the packer truck driver. They can avoid duplication of service by
establishing a set pattern that is followed each time a particular
route is covered. The satellite operators should work closely enough
to the packer truck to minimize haul distances and to avoid losing it.
The packer truck driver should help collect wastes and unload the
satellite vehicle.
Miscellaneous Information. Each satellite operator should have a
40- to 60-gallon, lightweight, manageable container to eliminate
carrying the homeowner's receptacles back and forth.
Establishing good customer relations can be extremely helpful to
the operators. Thoughtful residents will remove objects that obstruct
access to the storage point. Placing of wastes in paper or plastic bags
by the residents improves collection handling and prevents loose
articles from falling out of the satellite vehicle while it is moving.
Systems Comparisons
A residential solid waste collection system should attempt to
provide the most convenient, aesthetic, and sanitary service possible
to the customer in the most efficient and economical manner in
conformance with considerations for the health, safety, and morale
of the employees. Comparing one collection system with another
requires qualitative and quantitative evaluations of each of these
desirable features.
Qualitative Evaluation. The most convenient waste collection
service that can be provided a homeowner is pickup at the point of
storage. This function can be carried out by walking collectors or
personnel riding satellite collection vehicles. Observations made of
both methods indicate that the satellite vehicle system provides a
more sanitary service. Walking collectors tend to spill wastes at the
12
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storage point because they try to minimize the number of trips they
have to make to the packer truck by consolidating wastes from
several containers into one receptacle. In contrast, the satellite
operator merely has to dump the wastes into a 1- or 2-yard capacity
hopper on his vehicle.
The use of satellite vehicles facilitates the work. For the average
dwelling located 100 feet from the street, a driver walks 20 feet to a
storage point, while a walking collector covers about 300 feet. As
a result, the driver does not become as tired and is less likely to
be injured by lifting and carrying heavy loads.
The collection agencies studied reported that employee morale
rose and absenteeism fell after satellite vehicles were put into service.
This was due in part to the fact that satellite vehicle operators are
usually more highly regarded and compensated than walking
collectors. In addition, they have shelter in increment weather.
From the homeowner's viewpoint, the satellite vehicle represents a
technological advance on the part of the collection agency, and at
least some of his natural antagonism toward the waste collector is
thereby eliminated. This changed attitude is bolstered by the fact that
the packer truck does not make as many reverse movements as in the
walking collection system, and children at play are less likely to be
hurt.
There may, however, be disadvantages to the use of satellite
vehicles because: (1) high winds or speeds cause waste to blow out
of open hoppers; (2) many of the vehicles are excessively noisy;
(3) careless operators can damage lawns, shrubbery, and flowers.
Quantitative Evaluation. The efficiencies of the two systems can
be determined by comparing the total number of dwelling units each
could service under identical conditions. (In this study, observed
satellite efficiencies were compared with those estimated for walking
crews servicing the same area.) On this basis, satellite units
outperformed walking crews in five of the six study areas (Table 7).
The ultimate comparison between alternative methods of collecting
residential solid wastes is the relative cost each incurs in accomplish-
ing the same objective. Measured against the basic criterionannual
collection cost per average dwelling unitthe satellite system was
found to be cheaper in four instances, equal in two, and more
expensive in two. The satellite cost spectrum ranged from 24 percent
less to 75 percent more than that for the walking method (Table 7).
(10527
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