Requirements, Constraints and Trade-offs

≈ 44 min

Requirements, Constraints and Trade-offs

Requirements say what a system must achieve; constraints limit the possible solutions. A trade-off compares alternatives only after non-negotiable safety, legal and performance constraints have been separated from preferences.

Worked example. A rural footbridge may need a minimum load rating and flood clearance. Low cost matters, but it cannot justify violating a mandatory safety factor.

Reasoning routine. Name the system boundary, evidence required and one condition under which the conclusion could change.

Which engineering action best reflects this lesson's constraint?

Reject an option that fails a mandatory safety constraint before scoring preferences.

Choose the first attractive solution and justify it later.

Ignore a boundary, unit or failure condition.

Assume a single test result applies everywhere.

Write the key term for this lesson: constraint.

A team must make a defensible next decision. Which option is strongest?

Specify a minimum load and flood clearance before comparing bridge materials.

Hide the uncertainty so the result looks complete.

Treat a preference as a mandatory safety requirement.

Change the test after seeing an inconvenient result.

Which task would provide stronger transfer evidence after studying Requirements, Constraints and Trade-offs?

Apply the idea to a new context, state assumptions and justify a trade-off.

Repeat the lesson heading without using a model.

Copy a result without checking units or risk.

Choose a solution before defining the need.