Geoscience Reference
In-Depth Information
21.2.2.5
Modeling Dynamic Aspects of Location Decisions
A majority of health facility location applications discussed in this section assume
a static environment: demand is known and fixed, and facilities are static. These
assumptions may be realistic for short term planning problems. However, facility
location decisions are often made at a strategic level with a long term impact.
Therefore, if changes in the demand or in other relevant parameters are expected
in the long term, then multi-period models may be more appropriate. For instance,
we may observe seasonal effects in demand because of nomadic population groups
or because of tourism. Ndiaye and Alfares (
2008
) developed a multi-period integer
programming model to minimize the total cost for locating primary health centers
where the populations to be served occupy different locations in different seasons.
Benneyan et al. (
2012
) considered a multi-period model for the location of specialty
care clinics for veteran administration to minimize the total cost subject to access
constraints where the demand changes over time. Harper et al. (
2005
) developed
a discrete event geographical simulation model incorporating changes over time in
many aspects of the system, such as demand, services offered, and facilities opened.
Such changes can be used for a scenario analysis in the environment of simulation
models.
Mobile healthcare facilities are commonly used in rural areas to improve access.
Hodgson et al. (
1998
) developed an integer programming formulation for the
problem of covering tour planning for the mobile healthcare facilities in Ghana.
The objective is to minimize the total travel time of the facility while serving all
population centers within a range of the feasible stops. Note that this problem is
different from ambulance location problems since mobile facilities here serve for
primary care needs as opposed to emergency care situations.
21.3
Ambulance Location
A usual goal of ambulance location problems is to find locations for ambulances
(or ambulance stations) minimizing the number of ambulances (or ambulance
stations) needed while fulfilling a certain level of demand. Another possibility is
to maximize the coverage having a fixed number of ambulances (or ambulance
stations) available. The main aspect of the corresponding coverage models is that
the demand points must be reachable from the determined locations within a given
time interval. Concerning ambulance planning, a large variety of literature exists.
Reviews can be found in Marianov and ReVelle (
1995
), Owen and Daskin (
1998
),
Brotcorne et al. (
2003
), Galvão et al. (
2005
), and Li et al. (
2011
).
In general, ambulance planning can be done at three different levels: strategic,
tactical and operational level. At the strategic level, decisions concerning the
locations of ambulance stations are made. These decisions often have a long term
effect and last for several decades. The number of ambulances per station and the
movable locations are determined at the tactical level. The operational level includes
