adaptive_reroute #

Safety-driven route adaptation for winter driving.

The driver is on a planned route. Conditions ahead change — a hazard appears, weather worsens, the road two segments forward becomes risky. Should you reroute? When? Around what?

adaptive_reroute answers those questions. It consumes a RouteForecast and returns a RerouteDecision — whether to reroute, why, and (if yes) the detour waypoints to feed back to your routing engine.

Pure Dart. No Flutter.

What it gives you #

• RerouteEvaluator — decides when rerouting is justified given forecast hazards, current position, and configured thresholds.
• DetourPlanner — generates left/right waypoint pairs that bypass identified hazard zones, each offset by the zone radius plus a configured lateral offset. It produces candidate waypoints only; honouring detour-distance limits and routing-engine constraints is the calling routing engine's responsibility.
• RerouteDecision — typed result with shouldReroute, human-readable reason, detourWaypoints ready to hand back to a routing engine, and confidence (double?). It reports one of three facts: reroute, no hazard found on the assessed route, or could not assess the route (isAssessed == false, confidence == null). shouldReroute == false does not mean the route is safe — it is also what you get when the conditions were unknown. Read isAssessed first. (Before 0.2.0 there were only two outcomes and an unknown route was reported as "Route is clear" at confidence = 1.0; see CHANGELOG.)
• AdaptiveRerouteConfig — knobs for the hazard look-ahead window (hazardWindowSeconds), the minimum forecast confidence to act (minConfidenceToAct), and the detour waypoint offset distance (detourOffsetMeters).

Not yet implemented #

Documented as carry-forward gaps so the public API is honest about what currently ships:

• AdaptiveRerouteConfig.maxDetourFraction is declared but not yet enforced — no code path rejects a detour for exceeding it. Treat it as advisory and enforce detour-distance limits in your own routing engine until a future version wires it into evaluation.
• Minimum-progress / anti-thrashing logic (suppressing rapid re-reroute prompts so the driver is not alarmed repeatedly) is not implemented. RerouteEvaluator evaluates each forecast independently; debounce reroute prompts in your integration if you need this.

Install #

dependencies:
  adaptive_reroute: ^0.2.0

You'll also need route_condition_forecast to produce the input forecasts.

Use #

import 'package:adaptive_reroute/adaptive_reroute.dart';
import 'package:route_condition_forecast/route_condition_forecast.dart';

final evaluator = RerouteEvaluator();
final planner = DetourPlanner();

// You produced this from RouteConditionForecaster:
final RouteForecast forecast = ...;

final decision = evaluator.evaluate(
  forecast,
  currentPosition: currentLatLng,
);

// FIRST: did we actually have conditions to judge? `shouldReroute == false`
// is ALSO what you get when the route could not be assessed at all — do not
// paint that as a clear road.
if (!decision.isAssessed) {
  print('Route conditions unknown: ${decision.reason}');
  // Tell the driver the road ahead could not be assessed. Not an all-clear.
  return;
}

if (decision.shouldReroute) {
  print('Rerouting: ${decision.reason}');
  // Hand decision.detourWaypoints to your RoutingEngine to compute
  // the new route around the hazard zone.
  final newRoute = await routingEngine.calculateRoute(
    RouteRequest(
      origin: currentLatLng,
      destination: originalDestination,
      waypoints: decision.detourWaypoints,
    ),
  );
} else {
  // Assessed, and nothing found. `confidence` is inherited from the forecast
  // (the weakest segment along the route) — never a manufactured 1.0.
  print('No hazard found (confidence ${decision.confidence!}).');
}

When to use this #

When you've already shipped a navigation flow that consumes a forecast and you need a typed, tested decision layer for "do we reroute now, and if so around what?" — instead of re-rolling the threshold + waypoint logic per project.

If you don't yet have a forecast, depend on route_condition_forecast first; it produces the RouteForecast this package consumes.

License #

BSD-3-Clause. See LICENSE.