Prospective Model
Examines possible comparative signals before collision-history calibration is introduced.
Glossary
Key Terms Used Across Road Risk
Short definitions for the modelling, mapping, physics, statistics, and export terms used in the public site and live app.
Judge-Critical Terms
Key Terms Before Reading the Results
Comparative Output
A model output used for comparison under defined assumptions; not an official safety rating.
Annualised Comparative Model Output
The main reporting scale in the app and Results dashboard. It is not an observed annual crash probability.
Percentile
Sample-dependent context. A high percentile means high within that comparison set, not proven real-world danger.
Data Confidence
A summary of completeness and fallback reliance; it is not proof of real-world accuracy.
Validation
Road Risk currently has internal consistency testing; full operational validation remains future work.
Model Interpretation
Physics Terms
Statistical Terms
Mapping / Export Terms
Data Quality Terms
Definitions
Model, Data, and Interpretation Terms
- R.I.S.K.
- Roadway Infrastructure Safety Kinematics, the SciFest research project behind the live Road Risk application.
- Prospective Model
- A model that examines possible risk signals before collision-history data is introduced.
- Relative Risk
- A comparative indicator under defined assumptions, not an observed crash rate or official safety rating.
- Comparative Output
- The model value used to compare roads or scenarios on a consistent basis.
- Annualised Comparative Model Output
- The primary reporting scale used by the app for selected-road comparison.
- Daily Interpretive View
- A secondary conversion of the annualised model output to make small values easier to read.
- Curvature
- A measure of how strongly a road changes direction over distance.
- Radius of Curvature
- The estimated radius of the bend; smaller radius usually means a tighter curve.
- Heading Change
- The change in road direction across the analysed segment.
- Centripetal Acceleration
- The lateral acceleration needed to follow a curve at a given speed.
- Friction Coefficient
- A simplified value representing tyre-road grip under a surface or scenario assumption.
- Effective Friction
- The adjusted friction value after surface, weather, or scenario effects are considered.
- Safe Speed
- A friction-limited curve-speed estimate; not a legal speed limit.
- Slip Ratio
- A model indicator comparing required lateral demand with available frictional capacity.
- Stopping Distance
- Reaction distance plus braking distance under the active speed, friction, and scenario assumptions.
- Reaction Distance
- Distance travelled before braking begins, based on an assumed reaction time.
- Braking Distance
- Distance required to slow after braking begins; it scales strongly with speed.
- Scenario Modifier
- A controlled adjustment for rain, fog, fatigue, overspeed, vehicle type, lighting, surface, or related assumptions.
- Traffic Proxy
- An estimated exposure/context value used when direct traffic counts are unavailable.
- Percentile
- A position inside a sampled comparison set. The 87th percentile is higher than 87% of that sample under the same assumptions.
- Distribution
- The spread of model outputs across sampled roads.
- ECDF / CDF
- Cumulative graph views showing the proportion of samples below or above a selected output.
- Isochrone
- A reachability shape showing areas accessible within a time or distance condition.
- OpenStreetMap
- The open map-data source used for public road geometry and tags.
- Overpass API
- A public query service used to retrieve OSM road ways, geometry, and tags.
- GeoJSON
- A standard format for exporting geographic geometry and properties.
- CSV
- A tabular export format for reviewable model values and metadata.
- Data Confidence
- A caution level based on geometry quality, missing tags, fallback assumptions, and data completeness.
- Calibration
- Adjusting a model against empirical data. Full collision-history calibration has not yet been completed.
- Validation
- Testing whether outputs behave correctly and match external evidence. Road Risk currently has internal consistency testing, not operational validation.