Service Level Networks When It Literature Review

In other words, the facilities that are available will be laid out in the best possible pattern and fashion so as to maximize efficiency and convenience for people who use the services (Handler & Mirchandani, 1979). There is obviously no way to put all of the facilities into the same space, and some of them take up more land than others, but there is no reason that urban planning officials, city leaders, and companies that want to build in a particular area cannot work together to meet everyone's needs. Often they want to accomplish this, but they simply are not sure what the best way to go about it would be.

Consider, as an example, a network model of an urbanized area, shown on the following pages and reproduced from Larson & Odoni, 1997-1999 http://web.mit.edu/urban_or_book/www/book/chapter6/6.5.2.html.

All of the nodes (a through H) indicate points at which service demands are being generated. Major roads in the area also intersect at these nodes. A new facility is expected to be located in the area, and the prospective users of that facility will need to travel to it if they want to use the services provided there (Larson & Odoni, 1997-1999). They cannot simply make a phone call or conduct their business online. The demand figures for the services (on a daily basis and in units of 100s) are seen in parentheses next to each node. The numbers next to the links are length of road segments, measured in miles. In order to determine where the facility should be located, the information in the figure can be used to determine the shortest average travel distance (Larson & Odoni, 1997-1999). This is an excellent way to figure out the best location for a facility, and to avoid the problems that often come from poor planning of a facility's location (Lock, 1996). From the information collected based on the figure, it is possible to calculate minimum distance figures, as shown here:

Then, the results would be extrapolated and tabulated:

The same type of figures can also be used for more rural areas, where the nodes would then be towns, instead of points within one town (Larson & Odoni, 1997-1999). This is an important issue for medical and other emergency services, because it is vital that these services are set up to minimize the distance they will have to travel when responding to a call for help. The services will likely need to be located within one of the towns, but calculations will need to be performed to determine which town, just as they would be performed to determine where, within a specific town, something should be located so the travel distance for everyone involved will be minimized as much as possible (Larson & Odoni, 1997-1999).

Consider, as well, that the calculations that allow a person to determine where a facility should be placed based on median issues can also be used to determine where more than one facility should go. That is great for cities that are expanding and looking to add more facilities, and also for urban areas that are revamping and reinventing themselves to the point that they are trying to bring in more business (Mirchandani & Odoni, 1979). It is also good for cities that know they need to adjust their layout, or that see the need for services that are not where they should be for maximum efficiency (Larson & Odoni, 1997-1999). As urban areas grow and spread out, one fire station, police precinct, or medical facility might not be enough (Toregas, Swain, Revelle, & Bergman, 1971). They need more, and determining where to place that facility can literally make the difference between life and death for some people who need those types of services.

Median problems are not the only issue, however. There are also requirements problems that must be addressed. Facilities have to be in certain places to achieve the standards that they must meet in order to be effective (Larson & Odoni, 1997-1999). These standards could have been set by their parent company, or they could have been set by city, state, county, or federal leaders who have imposed specific rules and restrictions on companies in a particular area (Rosenfeld, 1994). When the question of where to place a facility and how to handle things most effectively is asked from a requirements standpoint, the same basic calculations can still be used as a baseline to provide answers (Larson & Odoni, 1997-1999).The question, at that point, then becomes more about the smallest number of facilities that can be used in order to achieve specific performance standards, as well as where those facilities need to be located (Larson & Odoni, 1997-1999). The two areas (location and number of facilities) must work together if requirement issues are to be solved. Congress has guidelines that state that 95% of rural calls for medical assistance must be able to be reach within a 30-minute time frame (Larson & Odoni, 1997-1999). Ninety-five percent of urban calls must be reachable within a 10-minute window (Larson & Odoni, 1997-1999). Because those are requirements, they have to be used when determining where to place facilities. If they are ignored, there can be serious consequences.

Because there are other factors -- like service problems, bad weather, or busy times where it is harder to get to someone quickly -- it is very important that facilities are actually often closer than they need to be to the people who need their services (Golden, 1976; Kamara & Augenbroe, 2002; Krolak, Felts, & Nelson, 1972). That way, they minimize the chances of not being able to get to people as fast as they should to meet the requirements (Larson & Odoni, 1997-1999). Knowing how far away from a facility people can be gives the analyst a good point to begin working from. In large areas where it is very rural and people are spread out, there may be the need for more than one emergency facility in order to meet the requirements (Larson & Odoni, 1997-1999; Revelle & Swain, 1970).

When center, median, and requirements problems can all be solved, it opens the door for other subsets of facilities -- such as those that people want located as far away as possible (Larson & Odoni, 1997-1999). These often include recycling centers and landfills, as well as factories and other companies that produce a lot of pollution or other problematic issues within a geographic area (Church & Garpinkel, 1978; Beltrami & Bodin, 1974). Other facilities, like recreation centers and parks, are set up using similar calculations. They should not be too far away from the average citizens of the town or city, and they need to be in areas where their use and efficiency will be maximized (Larson & Odoni, 1997-1999). It is not always possible to put a facility exactly where it 'should' be, but the goal of urban planning and facility management is to put facilities as close as possible to where they ultimately should be located, in order to provide the most good for the largest number of local citizens.

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