What is observed, derived, selected or substituted?

Search the inputs used by the App and see their model applicability, source, units, affected calculation and interpretation limit.

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Reading rule

Selected settings are controlled scenarios

Weather, surface, lighting, behaviour, vehicle and speed settings let a researcher compare the same road under different assumptions. They are not claims about what happened at a real place or time.

Input register

Filter the current public assumptions

10 of 10 inputs shown

Input	Type	Models	Affects	Source	Unit	Limitation
Road centreline geometry	observed	2.0, 3.2	Length, turn and geometry calculations	OpenStreetMap way coordinates or reviewed fallback geometry	WGS84 coordinates	Mapped centreline geometry is not a surveyed lane path.
Curvature and equivalent radius	derived	2.0, 3.2	Curve demand and local geometry evidence	Selected road geometry using the applicable model method	m⁻¹ and m	Sparse or unsupported geometry can make a local estimate unavailable.
Surface and friction	observed	2.0, 3.2	Curve/friction and braking comparisons	OSM surface tag where available; visible model fallback otherwise	dimensionless coefficient	Actual tyre-road friction is not measured live.
Friction fallback	fallback	2.0, 3.2	Curve/friction and braking comparisons when surface evidence is incomplete	Versioned model constant	dimensionless coefficient	A fallback keeps the calculation available but is not an observation of the road.
Reaction time	selected	2.0, 3.2	Reaction distance and total stopping-distance comparison	Active scenario or vehicle profile	s	Does not observe an individual driver's response.
Weather and visibility	selected	2.0, 3.2	Friction, visibility and scenario factors	User-selected scenario	Not applicable	Not a live weather observation or claim about past conditions.
Behaviour settings	selected	2.0, 3.2	Reaction, speed and scenario factors	User-selected scenario	Not applicable	Fatigue, distraction, alcohol and overspeed settings do not describe real drivers at the location.
Road classification	observed	2.0, 3.2	Road context, speed fallback and exposure proxy	OpenStreetMap highway tag	Not applicable	Road class is not measured traffic exposure.
Speed context	observed	2.0, 3.2	Lateral demand and stopping-distance comparison	OSM maxspeed tag where interpretable; visible fallback otherwise	km/h	A tag or fallback is not evidence of actual vehicle speed.
Traffic exposure proxy	derived	2.0, 3.2	Comparative output context	Road class and versioned model rules	Not applicable	It is not an AADT measurement and cannot replace measured exposure in empirical evaluation.

Road centreline geometry

observed

Models: 2.0, 3.2
Affects: Length, turn and geometry calculations
Source: OpenStreetMap way coordinates or reviewed fallback geometry
Unit: WGS84 coordinates
Limitation: Mapped centreline geometry is not a surveyed lane path.

Curvature and equivalent radius

derived

Models: 2.0, 3.2
Affects: Curve demand and local geometry evidence
Source: Selected road geometry using the applicable model method
Unit: m⁻¹ and m
Limitation: Sparse or unsupported geometry can make a local estimate unavailable.

Surface and friction

observed

Models: 2.0, 3.2
Affects: Curve/friction and braking comparisons
Source: OSM surface tag where available; visible model fallback otherwise
Unit: dimensionless coefficient
Limitation: Actual tyre-road friction is not measured live.

Friction fallback

fallback

Models: 2.0, 3.2
Affects: Curve/friction and braking comparisons when surface evidence is incomplete
Source: Versioned model constant
Unit: dimensionless coefficient
Limitation: A fallback keeps the calculation available but is not an observation of the road.

Reaction time

selected

Models: 2.0, 3.2
Affects: Reaction distance and total stopping-distance comparison
Source: Active scenario or vehicle profile
Unit: s
Limitation: Does not observe an individual driver's response.

Weather and visibility

selected

Models: 2.0, 3.2
Affects: Friction, visibility and scenario factors
Source: User-selected scenario
Unit: Not applicable
Limitation: Not a live weather observation or claim about past conditions.

Behaviour settings

selected

Models: 2.0, 3.2
Affects: Reaction, speed and scenario factors
Source: User-selected scenario
Unit: Not applicable
Limitation: Fatigue, distraction, alcohol and overspeed settings do not describe real drivers at the location.

Road classification

observed

Models: 2.0, 3.2
Affects: Road context, speed fallback and exposure proxy
Source: OpenStreetMap highway tag
Unit: Not applicable
Limitation: Road class is not measured traffic exposure.

Speed context

observed

Models: 2.0, 3.2
Affects: Lateral demand and stopping-distance comparison
Source: OSM maxspeed tag where interpretable; visible fallback otherwise
Unit: km/h
Limitation: A tag or fallback is not evidence of actual vehicle speed.

Traffic exposure proxy

derived

Models: 2.0, 3.2
Affects: Comparative output context
Source: Road class and versioned model rules
Unit: Not applicable
Limitation: It is not an AADT measurement and cannot replace measured exposure in empirical evaluation.