Example1: Value of (Partial) Information on
Vehicle
Location
The Bonded Taxi Company has been losing revenue recently because of the
overambitiousness of some of its own drivers. The radio dispatcher
usually assigns that cab which claims to be closest to the scene of a
call for cab service. However, some of the more ambitious drivers have
been claiming to be "right
around the block," when actually they might be at a distant location.
Such a car takes a long time to reach the scene; upon arrival, the
driver finds either a very dissatisfied customer who will never again
use Bonded or no customer at all (because the customer called another
cab company).
The Urbtronics Corporation has offered to sell Bonded a
.1-mile-resolution car-locator system, which, it is claimed, would
provide the dispatcher with accurate position information, thereby
eliminating distant dispatches caused by overly ambitious drivers. Other
advantages of the car-locator system would include safety to drivers and
better tracking of actual passenger mileage.
You have been hired to evaluate the advantages (and disadvantages) of
the car-locator system. What do you do?
Example 2: Location of Garbage Incinerators
A mayor of a large city has discovered, to his surprise and
consternation, that the city's refuse-collection trucks spend more time
every day in moving back and forth between the city and a few remote
garbage dumping sites that the city uses than in collecting garbage from
city streets. It has been decided that several environmentally safe
garbage incinerators will be built at a number of isolated locations
within the city's boundaries, so that travel distances for unloading
garbage can be reduced drastically. About 10 potential (and politically
feasible) sites have been identified. The following interrelated
questions must now be answered:
| a. | How many incinerators should be
built?
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| b. | Where, among the available sites,
should the incinerators be located?
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| c. | Which "truck runs" should be
assigned to which incinerator?
|
Example 3: School-Bus Routing
For many suburban communities, especially those with relatively low
population densities, the cost of transporting students to and from the
community schools represents an important fraction of the annual school
budget. In a large number of these cases the design of bus routes has
been made on a haphazard basis with new bus stops and routes added as
new children entered the school system. It is often possible to find
instances where two or more different buses make stops at the same
location to pick up different sets of students attending the same
school. An additional problem is that, because of inefficient route
design, some students are transported to school much before class time,
thus increasing the need for the presence of supervisors at the schools,
for additional recreational facilities, and so on.
An improved route-design process would offer the dual benefit of (1)
reducing the number of bus runs and transportation costs, and (2)
improving the quality of service to the students. Can such a process be
devised?
Example 4: Relocation Strategies for Fire
Companies
Although the average utilization of firemen is less than 25 percent in a
particular city, the city is still experiencing unusually long delays in
reaching some serious fires. These occur because demand patterns peak
between 7: 00 P.m. and 9: 00 P.m., and one large fire (or several
smaller ones, or false alarms) can "clean out" the fire stations in an
area. The department has previously allowed dispatchers to move up (or
relocate, reposition) certain companies. But with current levels of
congestion they cannot adequately perform this task, because of heavy
peak workloads and a lack of quantitative guidelines on how the
relocation is to be done.
You are working for SOLVEIT Consulting Associates. You have been hired
by the fire department to devise improved relocating strategies. A
real-time computer capability is being implemented by the department and
you have the freedom to use the computer in your system design. Design
an approach and a solution method for this problem.
Example 5: Effects of a Law on Police Tours of
Duty
Since the state legislature passed the "three-tour statute" in 1922, the
police department of a large city has been constrained by law to
allocate an equal number of police officers to each of the three tours
of duty (midnight to 8:00 A.m., 8:00 A.M. to 4:00 P.m., and 4:00 P.M. to
midnight). In recent years this constraint has been
particularly troublesome, since near-saturation
loads occur during predictable periods, but to relieve the congestion,
additional officers would have to be added to the force around the
clock. This is prohibited by budgetary considerations.
Examining this situation, the in-house planning and research group sees
an opportunity to use simulation and analytical models in a very
important way. Instead of accepting the existing statute as a "given"
constraint, the group plans to examine how the patrol force would
function if the law were modified to allow tours with nonequal numbers
of operating personnel. The group is convinced that the current total
number of officers available is sufficient to handle the needs of the
city if the tours could be restructured (perhaps even allowing
overlapping tours) to reflect the widely varying call-for-service rates
and the needs for preventive patrol.
The group initially plans to use queueing models to get a rough idea of
the number of personnel required by place and by time of day to achieve
a "reasonable level of service." Then response and patrol models will be
used to structure thinking about sector design, workloads, preventive
patrol coverage, and so on. Finally, several detailed simulation tests
will be performed to determine the extent of improvement obtained by
reallocating the officers. if the results are sufficiently promising,
the group plans to make the findings of the study publicly available.
Eventually, it is hoped that this may cause a revision in the current
law.
Working as the study group, how do you proceed?
Example 6: Redesigning a City's Ambulance
Services
Currently, a city's emergency ambulance needs are handled by several
private companies. These companies have been facing a deteriorating
financial situation, with labor and maintenance costs increasing and a
growing number of indigents unable to pay the cost of ambulance service.
The companies cannot afford the expense of highly trained drivers and
attendants; but a recently passed state law requires that all drivers
have substantial paramedical training by January I of next year. Given
this situation, it is highly probable 'hat the private companies will go
out of business and that some other means of providing ambulance service
will have to be provided.
The mayor's office has requested that a study group examine and evaluate
alternative proposals for providing ambulance service:
| a. | Incorporate ambulance service
into police department operations.
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| b. | Have a separate city-sponsored
ambulance fleet.
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| c. | Subsidize current companies or
a merged version of those
companies.
|
As the appointed study group, structure and analyze this problem, paying
particular attention to operational, economic, and service-related
issues.
