Question

Case Study 2 Alfreton has to decide on the location of a new factory and five sites are currently being considered: Ripley, Heanor, Heage, Little Eaton and Codnor. Four key factors have been identified in this decision. () The visual impact of the site on the environment (n) Accessibility to transport (ii) Risk of polluting the local environment (iv) The cost of developing the site. The managers evaluated the different sites in the following way: Benefits Visual Impact Site Transport Risk Costs Cm Ripley 100 60 35 100 20 70 25 Heanor 80 Heage 40 17 Little Eaton 20 100 12 60 Codnor 70 The managers considered that the risk of pollution was the most important factor. The visual impact on the environment was 70% as important and the accessibility to transport was 50 % as important as the risk of pollution. Questions a) Calculate the swing weights b) Determine the Aggregate Benefits

Answer 1

As given, risk of pollution is the most important factor. Let's say, we assume weight of 100 for risk of pollution.

Similarly, visual impact is 70% as important as risk of pollution. Hence, the weight of visual impact will 70% * 100 = 70

Accessibility to transport is 50% as important as risk of pollution. Hence, the weight of visual impact will 50% * 100 = 50

We will now calculate the normalized weights as per below calculation

	Original weights	Normalized weights
Risk of pollution	100	(100/220)*100 = 45.45
Visual impact	70	(70/220)*100 = 31.82
Accessibility to transport	50	(50/220)*100 = 27.73
Total	220	100

Hence, normalized weights/ swing weights is Risk of pollution (45.45), Visual impact (31.82), Accessibility to transport (27.73).

Now, calculating aggregate benefits for each site

Aggregate score for each site = Sum (Value * Normalized weights)

	Risk of pollution	Visual impact	Accessibility to transport	Total Aggregate score
Normalized weights	45.45	31.82	27.73
Site value and aggregate
Ripley value	60	100	0
Ripley aggregate	45.45 * 60 = 2727	31.82 * 100 = 3182	27.73* 0 = 0	(2727 + 3182 + 0)/ 100 = 59.09
Heanor value	100	20	70
Heanor aggregate	45.45 * 100 = 4545	31.82 * 20 = 636.4	27.73* 70 = 1941.1	(4545 + 636.4 +1941.1)/ 100 = 71.23
Heage value	0	80	40
Heage aggregate	45.45* 0 = 0	31.82 * 80 = 2545.6	27.73* 40 = 1109.2	(0+2545.6 + 1109.2)/ 100 = 36.55
Little Eadon value	30	20	100
Little Eadon aggregate	45.45* 30 = 1363.5	31.82 * 20 = 636.4	27.73* 100 = 2773	(1363.5 + 636.4 + 2773)/ 100 = 47.73
Codnor value	60	0	70
Codnor aggregate	45.45* 60 = 2727	31.82 * 0 = 0	27.73* 70 = 1941.1	(2727 + 0 + 1941.1)/ 100 = 46.68

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