The International Engineering Alliance defines engineering as:
Engineering: (n) an activity that seeks to meet identified needs of people and societies by the purposeful application of engineering sciences, technology and techniques to achieve predicted solutions that use available resources efficiently, are economical, that manage risks; engineering is carried out by practitioners performing roles differentiated by the level of problem analysis and solution, the activity to be managed, risk and responsibility.
The International Engineering Alliance also defines three types of engineering problems:
- Well-defined
- Broadly-defined
- Complex.
How can an engineering problem be ‘well-defined’ or ‘broadly-defined’?
Standards Australia defines performance-based and prescriptive standards as follows:
Performance Based Standards—have their requirements expressed in terms of performance, i.e. outcomes to be achieved. This approach leaves freedom for the development of innovative technical methods to meet the requirements of the Standard.
Performance Based Standards include the criteria, testing or other approved form of verification required to assess performance and to ensure consistency across the solutions developed to meet requirements.
For example, a requirement for a hypothetical wall plug suitable for hanging a mirror might state ‘The wall fixing shall support a weight of 40kg when tested in accordance with the test method in Appendix A.’ This leaves the manufacturer(s) the option of how they design the wall plug – nylon, brass, chemical and so on, as long as it supports the weight.Prescriptive Standards—express requirements in precise, often quantitative, terms. This leaves little opportunity to depart from the specifications in the Standard.
Using the hypothetical wall plug example again, a Prescriptive Standard might state ‘The 40kg wall fixing shall consist of a 2cm expansion case in accordance with Figure 1, together with a ¼in. Whitworth mild steel zinc plated nut and matching 3cm threaded hook in accordance with Figure 2’.
A prescriptive standard can well-define an engineering problem. The solution is defined. Little or no engineering judgement is required. Within railway control systems engineering, examples are:
- Application design using templates
- Function testing.
A performance-based standard can broadly-define an engineering problem. The outcomes are defined, but there are multiple (usually well-trodden) ways to achieve those outcomes. Some engineering judgement is required. Within railway control systems engineering, examples are:
- Application design beyond templates but within existing principles
- Principles testing.
Complex engineering problems are beyond what can be defined in a standard (prescriptive or performance-based). Significant engineering judgement is required. Within railway control systems engineering, examples are:
- Writing standards
- Standards waivers
- Novel application design
- Equipment design
- Tester in Charge work.
I note that a lot of signalling design falls into the ‘broadly-defined engineering problem’ category.
The International Engineering Alliance defines the occupational categories for work with the different types of engineering problems as:
- Engineering technicians (aka engineering associates) work with well-defined engineering problems
- Engineering technologists work with broadly-defined engineering problems
- Professional engineers work with complex engineering problems.
This is summarised in Table 1.
| Occupational category… | Professional engineer | Engineering technologist | Engineering associate |
| Works with… | complex engineering problems | broadly-defined engineering problems | well-defined engineering problems |
| Which can be legally defined as… | beyond standards | only in accordance with a standard | only in accordance with a prescriptive standard |
| Requires… | significant engineering judgement | some engineering judgement | little or no engineering judgement |
Professional engineers are professionals. Engineering technologists and engineering associates are paraprofessionals.