Definitions
The definitions the handbook states explicitly, gathered here with links to where each is applied.
The building blocks
Module
A set of interconnected tools, models or methods with specific objectives, inputs and outputs, with clearly defined information flows across the DSP.
A module must therefore have three things:
| Requirement | What it rules out |
|---|---|
| Specific objectives | A general-purpose toolbox |
| Specific inputs and outputs | An undefined interface |
| Clearly defined information flows | Outputs nobody has a route for |
Modules may also be used as standalone approaches, to guide users on specific methods or to extend existing workflows and appraisal knowledge.
Process
Each key process is defined by an interaction of modules and sub-processes that collectively generate an aggregated outcome that informs subsequent or preceding processes, enabling iterative refinements.
Note preceding. A process output can travel backwards through the cycle as well as forwards.
Systems
System
The handbook takes its definition from Meadows (2008), page 11:
An interconnected set of elements that is coherently organized in a way that achieves something.
Elements may be physical elements or social constructs such as ideas or organisations. They interact and influence each other, and those interactions can create complex patterns which may not be understood through reductionist analysis.
Systemic resilience
From the IPCC Glossary:
A property of an infrastructure system that arises dynamically when the national infrastructure is organized in such a way that it can provide agreed critical services (power, heat, communication channels, mobility services, potable water, and wastewater and waste removal) despite endogenous and/or exogenous hazards, and despite the addition, modification and removal of infrastructure components.
The key claim is that resilience arises from how a system is organised, not from the strength of individual components.
The five system groups
| Group | |
|---|---|
| Climate change | The changing environmental conditions the system operates in |
| Assets | The physical infrastructure |
| Networks | How assets combine into connected systems |
| Users | The people and organisations that depend on them |
| Policy and organisational contexts | The institutions, rules and responsibilities around them |
The source disagrees with itself on the count
The purpose section names five groups; the methods section names four, omitting Climate change. See the note on this.
Risk
The risk relationship
Risk = Likelihood × Consequence
| Term | Definition |
|---|---|
| Likelihood | The probability that an asset will deteriorate, fail, or lose required performance within a defined period |
| Consequence | The severity of the resulting impacts |
Either may be represented using quantitative values, ordinal scores, qualitative categories, or a hybrid approach, depending on data availability.
Residual risk
The risk remaining after an intervention. The handbook requires that it always be recorded, rather than assuming an intervention removes risk completely.
The six risk responses
Accept, monitor, maintain, reduce, transfer, avoid.
Vulnerability hotspot
A location where vulnerability vectors concentrate, particularly where multiple vectors overlap. A hotspot may be large, such as roads across a county vulnerable to a hazard, or highly localised, such as a specific junction, village, road link or flood defence.
Criticality is undefined
The handbook explicitly labels the definition of hotspot criticality as a gap. How to define it, for example in terms of impact on transport performance, is unresolved.
Assessment framework
Criterion, indicator and measure
The three-level structure of the MCA framework:
| Term | Definition |
|---|---|
| Criterion | The outcome or aspect of performance assessed within a dimension |
| Indicator | The evidence or characteristic used to demonstrate performance against a criterion |
| Measure | The specific metric or qualitative assessment used to evaluate it |
Dimension
The higher-level outcomes or themes against which options are evaluated, providing the structure for organising criteria.
Impact matrix
A structured mechanism for linking intervention impacts to the assessment dimensions, serving as the basis for identifying criteria and indicators. Its stated purpose is traceability between identified impacts and the criteria derived from them.
Baseline, or do-minimum case
The case against which options are compared. Options should always be compared against a clearly defined baseline rather than judged in isolation.
Problem statements
| Level | Definition |
|---|---|
| Macro-level | Strategic transport challenges associated with one or more vulnerability vectors |
| Spatially specific | Critical hotspots, disaggregated from macro statements as understanding of risk and criticality improves |
Asset registry data model
The registry's fields fall into two partitions, which determine how each behaves over time.
| Partition | Definition | Examples |
|---|---|---|
| Constants | Set once, true for the life of the asset | Asset type, construction date, initial design service life, location |
| Variables | Can be updated | Service life, geometry, materials, history, regulation and compliance, strategic classification, loading, condition score, condition projections, and the history of both |
Data quality criteria
The six criteria asset information is managed against:
| Criterion | The question it answers |
|---|---|
| Accuracy | Is it right? |
| Completeness | Is any of it missing? |
| Consistency | Does it agree with itself and other records? |
| Timeliness | Is it current enough to use? |
| Traceability | Can you tell where it came from? |
| Relevance | Does it bear on the decision at hand? |
Qualities the risk method must have
Transparent, repeatable, proportionate to the available evidence, consistent across comparable assets, and capable of representing uncertainty and scenario-dependent change.
Principles of detailed appraisal
Proportionality, transparency, traceability and whole-life value.