Overview of decision support elements

The DSP is built from two kinds of element, and almost everything in this handbook is one or the other.

Element	What it is	Defined in
Process flow	A stage of the decision cycle. There are six.	Processes
Module	A set of tools, models or methods that a stage draws on. There are seven.	Modules

The six process flows are interconnected through a series of modules and established or tailored processes. That phrasing matters: the modules are not bolted on beside the stages, they are the connective tissue between them.

The master diagram

The Decision Support Process shown as six coloured stages left to right: Asset/Network Evaluation, Problem Framing and Scope, Risk Reduction Analysis, Detailed option assessment, Portfolio Optimisation, and Outcome Assessment. Transport Scenarios and Climate Scenarios feed into the first stage from above; Requirements, Context and Constraints feed into the second. Each stage contains the modules it draws on. Stages four and five sit inside one dashed boundary, with a Risk Assessment box below returning from Portfolio Optimisation into Detailed option assessment. Three outputs leave that boundary at the bottom: Funding and Budgets (Financial Case), Procurement (Commercial Case), and PM, Governance, Reporting (Management Case). — Figure 1. Decision Support Process: key stages, modules and process flows.

This single diagram carries more detail than the surrounding text, so it is worth reading closely. Three things it shows that the prose does not state.

1. Which modules each stage actually uses

The modules named inside each coloured stage are the ones that stage draws on. Read across, that gives a usage matrix:

Module	Evaluation	Framing	Risk reduction	Option assessment	Portfolio	Outcome
Asset Registry	Yes					Yes
Asset Performance	Yes			Yes		Yes
Risk Assessment	Yes				Yes
Resilience	Yes		Yes	Yes
Sustainability	Yes			Yes
System Interdependencies		Yes			Yes

Two patterns stand out. Asset and network evaluation is the heaviest user, pulling on five of the six, which is consistent with its job of establishing the baseline. And Asset Registry appears at the two ends only, at evaluation and again at outcome assessment, which is what you would expect of a system of record: read at the start, written back to at the finish.

2. What enters the process from outside

Two sets of external inputs feed the first two stages, and they are of different kinds.

Feeding	Inputs	What they are
Asset/Network Evaluation	Transport Scenarios, then Climate Scenarios	The modelled futures the baseline is tested against, supplied by the IMP
Problem Framing and Scope	Requirements, then Context, then Constraints	The decision's boundary conditions, supplied by the organisation and its stakeholders

3. Where the process delivers to

Stages four and five sit inside a single dashed boundary, and three outputs leave the bottom of it:

Funding and Budgets, labelled the Financial Case
Procurement, labelled the Commercial Case
PM, Governance and Reporting, labelled the Management Case

These are Treasury Five Case Model names

Financial Case, Commercial Case and Management Case are three of the five cases in the HM Treasury business case standard. Their appearance here shows exactly where the DSP is designed to hand over to the UK public-sector approval process, which is the practical meaning of the claim that it supports an Outline Business Case.

The diagram is the only place this connection is made. The prose does not mention it.

The feedback loop

The diagram shows one explicit loop. A Risk Assessment box sits below stages four and five, taking input from Portfolio Optimisation and feeding back into Detailed option assessment.

The reason is that bundling changes risk. A set of interventions combined into a portfolio does not carry the sum of the risks each carried alone, so once options are bundled the risk position has to be assessed again and the option assessment revisited.

What this chapter covers

Page	What you will find
Modules	What a module is, and all seven described
Processes	What a process is, and all six described
Data & Tools	How modules, processes, data, tools and outputs interact
Input & Output	The generic input-output logic and data schema
Methods & Principles	Core methods, principles and tool types used across the DSP

Three sections are awaiting source text

Data & Tools, Input & Output, and Methods & Principles are headings in the source handbook with nothing written beneath them. Nothing has been written in their place.