Geography Reference
In-Depth Information
provides the advantage of using the VRP model to establish driving directions
for each company that provides the optimal collection route by minimizing
travel time.
5.1. Limitations
Modeling is an effective approach to better understanding how certain
phenomena behave when, in reality, it is impossible to obtain that
understanding through actual implementation or real operations. A review of
the academic literature confirms that GIS network analyst is an established
approach to analyze and improve upon solid waste collection strategies.
However, it should be noted that models can only offer one realization of
many possible scenarios under a specific set of conditions set forth by the
model's assumptions. This research attempted to minimize any assumptions
through field work and data collected by the IRC. Some assumptions could
have been avoided had local companies been willing to provide information on
their collection strategy. This research assumes a uniform amount of 50
pounds of solid waste per household each week. While no one can estimate the
amount of waste per household, this amount is based on the total amount of
solid waste each company brings to the transfer stations. The totals are specific
to the City of Altoona and provide the most accurate representation.
Solid waste collection trucks were placed into three categories of mini (2
cubic yard loader), mid (12 cubic yard loader), and large (25 cubic yard
loader). However, some companies have multiple trucks of varying sizes,
including 14- and 20-yard loaders. The three categories best represent the
truck fleet observed. Even if the truck size of every company was confirmed,
there are several factors that affect the amount of solid waste a full truck can
haul. First is the age of the truck. New trucks pack much better than older
trucks due to hydraulic fatigue in older trucks. Truck maintenance is also
important as neglecting to grease fittings on a weekly basis weakens the
compactors ability to compact solid waste. A second factor is how households
choose to place their solid waste on curbside for pick-up. Waste placed in trash
cans and bins without a lid is prone to fill with rainwater or snow. Wet refuse
is much heavier but compacts much better. Last are the employees on the
routes. The more often they compact the waste in the truck the better
compaction weight one gets. Some employees only compact when the hopper
is completely filled thus reducing the amount of waste the truck can haul. Even
