Stop Distance LabDriver education · Offline workspace
Stop Distance Lab
Rehearse total stopping distance in feet and car-lengths—tune speed, grade, surface, and your own tap-tested reaction time, then pressure-test sudden-stop scenarios offline.
100% offline
No accounts or cloud at launch
3 segments
Perception · reaction · braking
9+ drills
Seeded stop/continue scenarios
On-device
Tap timing & SwiftData presets
Illustrative marketing figures; not App Store metrics.
Why a single workspace
Stop Distance Lab turns abstract “leave enough room” advice into a single offline workspace US drivers can actually rehearse. Set speed, road grade, surface condition, and perception-reaction assumptions, then watch total distance split into labeled perception, reaction, and braking segments with a plain-language formula panel and car-length equivalents. Run a multi-trial on-device tap test, feed your average into the model, and judge seeded “Will I stop?” moments—queue ahead, school-zone cone, amber dilemma, animal at fixed range—against the current envelope. Compare dry vs wet or car vs light-truck setups side-by-side, study vehicle-class primers and a factors glossary, save local vehicle presets, finish short mastery quizzes, and pin a Home Screen widget that shows real last-used totals. No accounts, no cloud, educational estimates only.
Core lab
Segmented stopping workspace
Dial speed, grade, dry/wet/snow-ice presets, and perception-reaction; read total feet broken into perception, reaction, and braking with an expandable formula and car-length scale.
Timing
On-device reaction tap test
Run multi-trial taps, see your average latency, and optionally apply it as the reaction component—timing never leaves the phone.
Decision
“Will I stop?” scenarios
Face fixed-range hazards with road context, choose stop or continue, and reveal whether your current envelope clears the obstacle.
Compare
Side-by-side condition compare
Stack two full setups—dry 45 vs wet 45, passenger vs light truck—with bar breakdowns per distance segment.
Study
Presets, glossary & quizzes
Load vehicle-class primers, named local presets, a factors glossary that jumps back into the lab, and mastery quizzes with instant keys.
Home Screen
Live Home Screen widget
WidgetKit shows total stopping distance for your last speed/condition preset and opens straight into the workspace—real local values only.
Scope
Educational envelope only
Banners remind you these are teaching estimates—not legal advice, not vehicle certification, and not a substitute for posted limits or instructor guidance.
Category · Education
Built for rehearsal, not telemetry
Free dense toolkit at launch: local presets, formula transparency, and scenario pressure-tests without signing in.