The document describes a methodology for generating functional variations of bus stop shelters. It identifies 5 major systems of shelters: roof, supporting structure, climate control, energy source, and graphic communication. It then decomposes each system and generates potential variations. This results in 1280 total possible combinations. The combinations are then "pruned" to eliminate impossible, harmful, impractical, or constrained options. This reduces the possibilities to 18 manageable variations. A likelihood metric is then applied to the variations to probabilistically forecast the most likely future shelter systems.

1. GENERATING FUNCTIONAL VARIATIONS OF THE SHELTER
by
Victor Molina
A paper presented in partial fulfillment
of the requirements for the course
Forecasting and the Evolution of Technology
ARIZONA STATE UNIVERSITY EAST
May 2003

2. GENERATING FUNCTIONAL VARIATIONS OF THE SHELTER
Introduction
This paper will be focused on generating functional variations of the shelter (bus
stop). The methodology used is based on “Generating Functional Variations Of The
Bicycle” written by Daniel Wilson, Ph.D., who is instructor of “Forecasting and
Evolution of Technology” class.
The methodology includes sequential steps from decomposing the shelter into its
functional systems to the generation of variations in each one of these functional systems
in order to predict or anticipate evolutions in the design of the shelter.
Some of the variations would be generated through adoption of ideas from other
technologies and adapting them to the functional scheme of the shelter.
SYSTEM VARIATIONS
The following have been identified as the major systems of the shelter.
Shelter (Bus stop) System
1. Roof
2. Supporting Structure
3. Climate Control
4. Energy Source
5. Graphic Communication (Signs and Advertisement)
Major functional systems are decomposed into various means for accomplishing the
purposes of the system
Roof
1. Metal roof
2. Translucent plastic roof
3. Textile roof
4. Organic (bio-designed) roof
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3. Supporting Structure
1. Fixed
2. Tensile
3. Modular
4. Robotic
5. Bionic
Climate control
1. Shade only
2. Shade + moisture dispenser
3. Shade + air cooling/heating
4. Sphere of comfort (climate bubble)
Energy Source
1. Electricity only
2. Photovoltaic only
3. Electricity + Photovoltaic
4. Electricity + Photovoltaic + Fuel Cell + Batteries
Graphic Communication
1. 3D images
2. Flat TV screen (active)
3. Flat Monitor (interactive)
4. Virtual Reality
Technical note:
In today’s shelters, supporting structures are commonly fixed (no further variation
or growth) and shade is the only climate control part of the system. Indeed, no energy
source is necessary for the use of the shelter. Additionally graphic communication
(advertisements, bus schedules, or signs) is printed. However, in cities located in desert
regions and semi desert regions, where (a) public places and streetscapes are being
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4. considered as a strategy toward downtown redevelopment, and (b) public transportation
is likely to be promoted, it is necessary to forecast variations of a new design of the
shelter that would cover the need of a potential group of users.
SUMMARY
The following variations of each particular system have been identified. The
number of variations of each system in parenthesis
Shelter (Bus stop) System:
1. Roof (4)
2. Supporting Structure (5)
3. Climate Control (4)
4. Energy Source (4)
5. Graphic Communication (4)
Total variations
If ni denote the number of variations in the i-th system, then the total number of
variations of the shelter in the product of the individual system variations, as follows:
Total variations = IIini = 4*5*4*4*4 = 1280
All the combinations will conform a “tree” that would have 1280 tips, each of which
represent a combination of proposed features, one selection from each system. Being
1280 a considerable large number of possibilities, reducing the number to a manageable
size would be necessary.
Pruning the tree
The rationale behind the elimination of combinations will include:
1. Eliminate impossible combinations
2. Eliminate illegal or harmful combinations
3. Eliminate impractical combinations
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5. 4. Eliminate combinations that might cause inner problem in the system
5. Eliminate combinations that could lead to behavioral constrains imposed by the
intended user
6. Eliminate combinations with legal restrictions
Shelter System After Pruning The Tree
After pruning the tree the possibilities of variation was reduced from 1280 to 18,
which is by far a much more manageable number of variations:
1. Supporting Structure
a. Tensile (.4)
b. Modular (.6)
2. Climate control
a. Shade only (.6)
b. Shade + moisture dispenser (.3)
c. Shade + air cooling/heating (.1)
3. Energy Source
a. Electricity only (.2)
b. Electricity + Photovoltaic (.5)
c. Photovoltaic + Fuel Cell + Batteries (.3)
Combination of systems = 2*3*3 = 18
Probabilities and forecasting
Dr. Wilson (2003) states: “Once the final feasible tree has been developed, than
probabilities might be placed on the branches to develop a probability forecast of future
(shelters). If actual probabilities can be determined, they may be used, but in lieu of
those, a certainty factor approach may be used. The paired-comparison method may be
used to determine relative rankings of the likelihood of the combinations being adopted
or adapted and weightings may be used to compute a likelihood metric that reflects the
opinion of the forecaster” (pp. 6-7).
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6. Likelihood Metrics and the Paired Comparison Method
The first step is to list all combinations within each category selected two at a
time. For instance, if we have n items within a category, there will be C= n(n-l)/2 pairs to
compare within the category. In the shelter system, there is 2 choices of roof, 2 choices of
supporting structure, 3 choices of climate control, 2 choices of energy source, and 2 in
graphic communication. The next step is to build a table of pairs by combining each item
with every item below it in the list. In each pair we make a choice on which one is the
most likely to happen on the future variations of the shelter, and then we check the
selected item. This procedure continues with all the pairs we have. After that, we tally the
checked items and rank them in descending order. The more likely to be in the future
variations of the shelter are those with grater number of votes.
Table 1. Paired Comparison Choices for Three Bicycle Subsystem
First Item Second Item Choice
1. Supporting System
1.1 Tensile vs. 1.2 Modular 1.2
2. Climate Control
2.1 Shade only vs. 2.2 Shade + Moisture dispenser 3.2
2.1 Shade only vs. 2.3 Shade + air cooling/heating 3.1
2.2 Shade + moisture dispenser vs. 2.3 Shade + air cooling/heating 3.2
4. Energy Source
4.1 Electricity only vs. 4.2 Electricity + PV 4.2
4.2 Electricity + PV vs. 4.3 PV + Fuel Cells + Batteries 4.2
4.1 Electricity only vs. 4.3 PV + Fuel Cells + Batteries 4.3
“To obtain the likelihood metrics (LM)” - Dr. Wilson (2003) continues – “we simply
divide the number of times a feature was selected…by the total of the selections in the
category where that feature appears” (p. 10). For example, under Climate Control
Features, we see that the sum of the selections is 3 (corresponding to the number of
comparisons made in category), so we divide each of the counts in the “Times Selected”
column by 3 to get 1/3, 2/3, and 0 fro the three choices of climate control system.
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7. Table 2. A Summary Of The Choices For The Bicycle Subsystem
System feature Times Selected Likelihood
Metric
1. Supporting system
1.1 Tensile supporting system 0 0
1.2 Modular supporting system 1 1
2. Climate control
2.1 Shade only 1 1/3
2.2 Shade + moisturizer 2 2/3
2.3 Shade + air cooling/heating 0 0
4. Energy source
4.1 Electricity only 0 0
4.2 Electricity + PV 2 2/3
4.3 PV + Fuel Cells + Batteries 1 1/3
Finally we may use the LM as if they were probabilities to determine path likelihood by
multiplying the LMs along the branches:
Table 3. A Tabular representation of Shelter Systems Combination
Electricity Electricity + PV PV + Fuel Cells + Batteries
Only
Modular Shade only (1/3) (1)(1/3)(0) = 0 (1)(1/3)(2/3) = (1)(1/3)(1/3) = .1089
(1) .2178
Modular Shade + Moist (1)(2/3)(0) = 0 (1)(2/3)(2/3) = (1)(2/3)(1/3) = .2178
(1) (2/3) .4356
Modular Shade + Cooling (1)(0)(0) = 0 (1)(0)(2/3) = 0 (1)(0)(1/3) = 0
(1) (0)
Tensile (0) Shade only (1/3) (0)(1/3)(0) = 0 (0)(1/3)(2/3) = 0 (0)(1/3)(1/3) = 0
Tensile (0) Shade + Moist (0)(2/3)(0) = 0 (0)(2/3)(2/3) = 0 (0)(2/3)(1/3) = 0
(2/3)
Tensile (0) Shade + Cooling (0)(0)(0) = 0 (0)(0)(2/3) = 0 (0)(0)(1/3) = 0
(0)
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8. Conclusion
The shelter combinations, for cities located in desert regions, in descending order of
likelihood are:
• Modular supporting structure, shade+moist, electricity+PV (.4356)
• Modular supporting structure, shade+moist, PV+fuel cells+batteries (.2178)
• Modular supporting structure, shade only, electricity+PV (.2178)
• Modular supporting structure, shade only, PV+fuel cells+PV (.1089)
References
JC Decaux [Online] www.jcdecaux.com/anglais/metiers/mobilierurbain/focus/index.htm
Wilson D. (2003). Generating Functional Variations of the Bicycle. College of
Technology and Applied Sciences. Arizona State University.
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