2.2 Technical feasibility
We have generated some scenarios for moving people and luggage around a site such as a major airport. How do we assess the technical feasibility of these scenarios? We do not intend to answer such a broad question at this point. However, we do need to be sure that the chosen technology is sound, otherwise the probability of things going wrong will be high.
We can determine whether a technology is mature. For example, the technologies of laying pavements, building stairways and so on is very mature, though new materials will from time to time appear on the market and influence the technology. An example is the use of extremely hard-wearing rubber tiles in places such as train stations, airports and the like to provide a more pleasant and safer surface to walk on, reduce noise levels and yet be nearly as durable as harder surfaces.
Some technologies are only relatively mature and are still undergoing active development. The use of fixed-rail or fixed-bed cars, trains and trams is an example: there has been continuous change in such technology to increase safety, improve the comfort of the ride, increase speed and reduce running and maintenance costs and side effects such as noise. The Paris Metro originally used iron-wheeled vehicles on fixed iron rails but has moved to rubber-tyred vehicles running on concrete ‘tracks’; both Gatwick and Stansted airports have automatic, driverless rail vehicles to move people.
Other technologies, such as superconductors and linear motors, are only just emerging: a few scale-model prototypes have been built to develop an understanding of the characteristics of the technology and to help make it usable at full scale and at an affordable cost. For example, the maglev train connects the new airport in Shanghai to the city’s metro system.
Not only do we need to assess whether a technology is mature, sound and applicable – we also need to assess a variety of technical aspects of any proposal. These vary enormously and often require experienced or expert people to evaluate them properly. Even the building of a house by an experienced building contractor requires this sort of assessment. For example, the soil on the building site will affect how the foundations have to be constructed. A house built on clay has different requirements from one built on sandy soil; one built on a hillside with the potential for slippage is different yet again from one built where the earth is stable. (A soil engineer may be called to take samples and prepare a report before building commences.) Marketing projects have to take into account the fact that markets vary due to climatic, cultural and economic differences: you cannot market air-conditioners very successfully in a cold climate, nor to people who cannot afford them. A software developer may need expert advice from the hardware manufacturer before undertaking a project using that manufacturer’s platform. A project to dig a well in the developing world will need an assessment from a hydrologist about the depth, suitability and extent of the local aquifers and water table.
You should bear in mind that cost is by no means the only factor determining whether a project is worthwhile, though its ease of measurement may tend to give it prominence. Several techniques exist for dealing with anything where cost is of less importance than other aspects of a project or product.
Features analysis is a method of gathering and organising information about different products which have the same purpose and comparing them in terms other than those of cost. Features are those elements of a piece of equipment, a system or some other major constituent of the project which are regarded as important in the context of the project’s requirements.
Assume that your company plans to publish a series of ‘how to’ books on a highly technical subject. You are asked to interview a number of ‘typical’ buyers and users of this type of book to find out what their needs are. You find that most of your subjects mention durability, portability, ability to keep the pages clean and ability to prop up the open book and have it stay open at the correct page. What, then, are the features?
If you look at the requirement for durability, then a feature might be the materials used for covers and pages, and the type of binding used. The binding is also a feature that will dictate whether an open book can be easily propped up and will stay open at the right page. Portability will probably be determined more by dimensions and weight. (You may have to find out more about this requirement: do people want to be able to carry the book under an arm, in a briefcase, in a pocket?) Being able to keep the pages clean will depend on the paper used, which will also have a bearing on the weight of the finished product.
Note that a feature, such as the type of paper used, can have a bearing on two or more other features (such as weight and ability to stay clean). One sample of paper may contribute more to one feature (saving weight) and less to the other (ability to stay clean), while another sample may be easier to keep clean but weigh more.
A features analysis of the proposed system components will focus attention on the features of any requirement that are likely to prove important to the achievement of something that works and that satisfies needs. The importance of these features needs to be determined so that competing proposals or products can be judged accordingly. (One inevitable feature is of course cost, but it may not be the most important feature.)
Undertaking a features analysis entails identifying those features in the requirements likely to be vital, or very important, to the final outcome of the proposal. When important features have been identified they can be given a weighting (or weight factor), which assigns a value that indicates the relative importance of one feature compared with all the others.
Each identified feature becomes a category with several constituent elements. If we take robustness of a system as an example, we can analyse ways in which a system can be robust: it continues to operate in spite of power failures; the communications channels will not fail; the central computer has to be designed so that a failure in the hardware will not cause the system to cease to operate; and so on. These elements are painstakingly listed, and each will have a point value attached to it so that the total number of points for the elements listed under one feature will be 1.00. Each feature will be assigned a weight factor which indicates its relative importance to other features looked at in the analysis. An example using the factor passenger/luggagecapacity in choosing a new motor car is shown in Table 4. The weight factor here (0.25) indicates that passenger/luggage capacity will make up one-quarter of the value given to the overall analysis of the new car.
|Feature/element||Weight factor||Point value|
|Front seat headroom||0.13|
|Front seat legroom||0.17|
|Back seat headroom||0.10|
|Back seat legroom||0.10|
|Total seating capacity||0.16|
|Luggage capacity in boot||0.14|
|Luggage capacity on roof-rack||0.08|
|Ability to rearrange seating||0.06|
|Glove box capacity||0.03|
|Other small item storage||0.03|
In this case we have chosen as an important feature of a new motor car the passenger and luggage carrying capacity. We can go further and identify other features for choosing a motor car, as shown in Table 5. Each such feature will then have the elements that constitute that feature also listed and given point values, and the total value of the features for an item will be 1.00.
Following the descriptions of features, weight factors and the elements that make up the features and their point values, each candidate product must be rated. Using the feature described in Table 4, motor car A might have sufficient front seat headroom for people 1.8 metres (6 feet) tall while motor car B might easily accommodate people of 1.95 metres (6 feet 4 inches). If a car-hire firm employs several drivers who are over 1.8 metres tall, they will have a preference – because of this element of the passenger and luggage feature – for motor car B, though other elements and features must enter into the final choice. In carrying out the features analysis, you would have to decide whether to give motor car B the full point value for front seat headroom of 0.13 and how much point value (perhaps only 0.09) to give motor car A. When all the elements of a feature have been rated for all the candidate products, they are added up. Let us say that motor car A has a point count of 0.58 for the passenger/luggage capacity feature and motor car B has a point count of 0.71.
All the features identified are assessed and point values added up. Then the point value for each feature is multiplied by the weight factor for that feature. Thus motor car A in our example will have a weight-adjusted rating for passenger/luggage capacity of 0.145, obtained by multiplying motor car A’s point count of 0.58 by the weighting assigned to passenger/luggage capacity (0.25); similarly B’s point count of 0.71 multiplied by 0.25 gives a weight-adjusted rating of 0.1775.
The weight-adjusted scores for all features being considered are then summed for each candidate product to obtain a figure of merit (FOM), and the candidate with the highest FOM should normally be the product chosen. (A figure of merit assigns a numeric value to a cost or benefit based on an arbitrarily decided and often weighted scale: for example, you might rate a computer according to the desirability of its speed, memory capacity and reliability.)
The problems with features analysis are fairly obvious:
- there may be many constituent elements for each feature
- deciding upon the actual weightings to use
- qualitative ranking systems (e.g. those using categories like poor, average, good and excellent) are more difficult to analyse though they may be easier to use when rating elements
- complete consensus about the weightings of features and rankings will rarely occur.
Thus the result of a features analysis is to some extent arbitrary. Nevertheless, a features analysis can be a highly valuable exercise since it will help an organisation to identify, rate and rank those features of a system which they find important more objectively.
Imagine you are planning to buy some luggage to use in your new job, which will involve a great deal of long-distance international travel over the next two or three years. You may need to be away from your home for up to six weeks at a time. You will need to be able to carry sufficient clothes for up to six weeks for a variety of climates, as you may spend a couple of weeks in Moscow in winter, followed by a couple of weeks in equatorial Africa. You should also expect to carry small amounts of paperwork and perhaps some sample
List what you feel will be important features to judge in comparing different makes of luggage. Assign weight factors to them.
Possible features of importance are: durability, empty weight, capacity, ease of carrying, security of locks, internal compartmentalisation, degree of water-proofness, ease of recognition at the luggage conveyor at the airport, appearance. You may have suggested others, depending on what is important to you. Likewise, any weighting you assign to these features will also vary, though the specification that you will do a great deal of travel for the next two to three years probably means that durability will have a relatively high rating.
Take the feature ease of carrying and list some elements that you feel make up this feature.
Some that occurred to us are: the comfort of the handle, the balance of the case, the presence of a shoulder strap (on smaller cases), the presence of wheels on larger cases, ease of using the wheels (e.g. does the case fall over when pulled along?), a strap or handle for pulling of sufficient length and strength to allow a person to walk upright while pulling the case along.
You may have thought of others.
(a) List the main steps of a features analysis.
(b) What is the value of doing a features analysis?
(a) Main steps are:
- Identify important features.
- Identify the constituent elements of each feature.
- List the elements.
- Attach a point value to each depending upon its relative contribution to the feature. Ensure that the sum of all the points for the elements of a feature adds up to 1.00.
- Assess the features using the constituent elements and assign the point values for each constituent assessed.
- Sum the point values.
- Multiply the sum of point values for each feature by the weight factor for that feature.
- Sum these for all features to obtain a figure of merit (FOM) for the candidate product.
Products can then be compared using their figures of merit.
(b) The value of doing a features analysis is in taking an objective view of the features identified in the requirements as key or important, then establishing a ranking system and applying it in an attempt to find the product whose features most closely meet the requirements.
Environmental and social factors
Increasingly, environmental or ecological factors must be considered when assessing the feasibility of any proposal. Such considerations may be prompted by a feeling that an organisation’s existing and potential customers would prefer to buy products which are less harmful to the environment than alternatives, or by concern among shareholders or employees, or may be demanded by health and safety legislation. It is beyond the scope of this course to discuss in detail the assessment of environmental factors, but Example 7 gives an idea of the types of things looked at in such an environmental impact assessment (EIA). When assessing the environmental impact of any project it is important to consider it over the broadest possible time span. In a manufacturing project, this means taking into account not only the impact of the product itself and any pollution created in the manufacturing process but also the raw materials and energy used for its manufacture and the method of its eventual disposal.
Hydro-electric power generation is an alternative to the use of coal to generate electricity. The building of dams to locate generators to provide a renewable energy source brings a substantial environmental benefit in comparison with the construction of power stations that use coal. It takes about 400 grams of coal to produce 1 kilowatt-hour of electricity, so a hydro-electric power station that has a capacity of 10 000 megawatts will reduce coal consumption by about 12 million tonnes a year. Hence, there will be a substantial improvement in air quality because of the reduced gaseous emissions (such as sulphur dioxide and carbon monoxide).
It is also increasingly common to assess social factors in determining feasibility; this is particularly true in projects undertaken in the under-developed world. These may range from social factors within a single group or office (for example, where a new technology is likely to be introduced) to broader social concerns about the effects of a project, process or product on employment, the health of workers and the general public, and safety issues. One of the earliest examples of incorporating these concerns into the development of software was the ETHICS (effective technical and human implementation of computer systems) method (Mumford, 1983). ETHICS looks at using participative methods to explore organisational issues such as goals, values and sources of job satisfaction in designing computer systems, and incorporating these issues with technical solutions into a design. Since then, participative methods to explore organisational issues have been the subject of many research projects (see, for example, McShane and Von Glinow, 2004). In addition, the tools and techniques used for EIA often include social factors, such as land use and employment, with physical and biological headings used to analyse environmental conditions (European Commission).
A reservoir behind a dam reduces the chances of flooding downstream from the dam, although reducing the water flow to prevent flooding places a constraint on the amount of electricity that can be generated. At the same time, a large reservoir increases the amount of gases emitted, such as methane, that are the by-products of rotting vegetation. While the control of water flow will affect the amount of downstream erosion of the river bank, the potential build-up of silt on the upstream side could reduce the effectiveness of the dam for electricity generation. The large volumes of water contained in reservoirs will also have an impact on the ecosystem. For example, some animal habitats will be threatened, while others may be helped.
Once the reservoir starts to fill up, the social impact will increase. For instance, people will be forced to move to a different location because the village or town where they live will be submerged, and a number of archaeological sites may be lost.
Other technical factors
Tram systems are seen as an important way of addressing problems of traffic congestion and public transport needs in large cities. Because trams are powered by electricity, there are environmental benefits (less noise and air pollution) in comparison with diesel-powered buses. The 1990s saw a revival of tram systems in the UK (see British Trams). Manchester Metrolink, which opened in 1992, made use of existing railway track owned by British Rail, which minimised disruption to road traffic during the construction phase. By concentrating on popular commuter routes, Manchester’s trams attracted nearly 20% more passengers than expected. In contrast, the tram system in Sheffield, which opened in 1994, made use of existing roads around the city. In order to minimise disruption to traffic, the tram routes were located on streets in areas that were in need of redevelopment, such as the derelict industrial area in the Don Valley. However, blocked access to shops and local traffic delays during construction alienated many local people along the route. This raised questions as to whether the new trams in Sheffield would attract sufficient passengers (at the time of writing, approximately 11 million passenger trips are made each year). The increased capacity of trams over buses contributes to the potential benefit with respect to traffic congestion, with each tram potentially removing 150 cars off the area’s roads (British Trams). For example, a new tram system opened in Nottingham with an objective of reducing congestion by taking up to 2 million car journeys off the road. Unfortunately, the project was affected by a lack of specialist staff (BBC, 2004).
Technical factors other than the maturity of a technology may be:
- the utility of the technology (for example, in the selection of computer systems for collecting fares for the new trams)
- the usability of systems (such as access to the new trams by disabled people)
- the degree of disruption during the construction or installation phase
- use of and improvement to existing infrastructure or the development of new infrastructure
- notions of general social utility (Sheffield’s choice of tram routes)
- marketability (Manchester’s choice of tram routes).
Assessing whether a particular technology is suitable for a particular situation will depend both on the situation and on the objectives of the organisation. Returning to our activity of developing scenarios about moving people and baggage, an airport authority with an existing large and busy airport will want a technical solution which will not be too disruptive to install and will work immediately, perhaps using a system of buses. An airport authority building a new airport can more safely choose a technical solution which might cause too much disruption if it were attempted in an existing facility, such as a fixed-roadbed system like a monorail. An organisation exploring novel applications for superconductors and linear motors may want to develop the technology of moving discs.
In addition to purely technological factors, technical constraints may apply to any plans. If you plan to start a restaurant business, the opening hours allowed by a local authority will be a constraint to consider, as perhaps will the availability of car parking facilities or public transport.
Make a very brief technological, social and environmental assessment in terms of questions to be asked of a plan to collect and recycle steel and tin-plate cans in a medium-sized town. (Note that we are not looking for the technical answers here, just the questions that might be asked.)
Spend no more than three to five minutes on this.
Our list of questions for this assessment follows.
- How mature is the process of recycling steel and tin-plate?
- Could local people be persuaded to recycle their tins?
- Are there reasonable places to put recycling collection points? Would it be better to have collections from homes?
- Is this likely to affect employment in the area?
- Would local people object to siting a recycling plant here (smells, noise, generation of more road traffic)?
- How much disruption would there be in building the plant?
- How much energy is consumed by the processes, compared to energy consumed in extracting raw materials for making steel and tin-plate? Where does the energy originate? How ‘clean’ or ‘dirty’ is the process of energy generation used in the locality?
- What are the waste products (including air, water and soil pollutants) generated by the recycling process, and how can these be minimised and handled safely?
- Can permission for the plant be obtained from the local authority?
- Is the road infrastructure able to support another industrial site in the area?
You may have other questions in your list.