A vision without a logic model is just a poster.
Logic models help transport professionals and planners visually map the relationships between resources, activities, and results. They are particularly useful for translating strategy into delivery, aligning teams, and clarifying assumptions.
1. What is a Logic Model?
A logic model is a structured diagram that links:
- Inputs (what you invest)
- Activities (what you do)
- Outputs (what you deliver)
- Outcomes (what changes)
- Impacts (long-term value).
This chain illustrates how planned actions are expected to create meaningful, measurable change. In transport planning, it supports:
- Program evaluation
- Business case development
- Performance reporting
- Cross-stakeholder alignment.
Example: A bus priority program logic model might begin with “funding and data” (inputs), followed by “corridor redesign and signal priority” (activities), producing “improved frequency and speed” (outputs), leading to “increased patronage” (outcome), and ultimately resulting in “reduced emissions and car dependency” (impact).
2. Inputs → Activities → Outputs → Outcomes → Impacts
3. Logic Models in Practice: Vision Zero Example
Vision Zero strategies (aiming for zero road deaths) often use logic models to:
- Map high-level targets (impact) to specific infrastructure changes (activities)
- Align enforcement, design, education, and policy into one causal system
- Track progress using intermediate indicators (e.g., % of roads under speed limits).
Logic Model Snapshot:
- Impact: Eliminate road deaths and serious injuries
- Outcomes: Lower speeds, safer crossings
- Outputs: Traffic calming treatments installed
- Activities: Design & implement safety upgrades
- Inputs: Safety audit data, capital investment.
4. Systems Thinking and Causal Pathways
Logic models also reflect systems thinking:
- Consider feedback loops (e.g., improved service leads to higher demand, requiring more investment)
- Identify unintended consequences (e.g., faster routes may attract more vehicles)
- Reveal leverage point; small actions with significant outcomes.
Using logic models helps break down complexity into manageable, testable assumptions.
Summary
- Logic models show the causal path from inputs to impact: they connect planning to outcomes.
- A good logic model clarifies what you’re doing, why, and what success looks like over time.
- The structure (Inputs → Activities → Outputs → Outcomes → Impact) helps organize both thinking and delivery.