fleet_hazard

Turn scattered vehicle reports into map-ready hazard zones. Clusters individual snow/ice reports by geography and severity — pure Dart, no Flutter dependency.

Use fleet_hazard when you need to aggregate telemetry from multiple vehicles into hazard zones that can be rendered on any map widget.

Features

• FleetReport model with road condition, timestamp, confidence, and position.
• HazardZone cluster model with severity, vehicle count, and average confidence.
• HazardAggregator pure-Dart clustering algorithm for snowy and icy reports.
• FleetProvider abstract interface so apps can swap simulated, local, or remote telemetry backends.
• Pure Dart package with no Flutter dependency.

Install

dependencies:
  fleet_hazard: ^0.3.0

Quick Start

import 'package:fleet_hazard/fleet_hazard.dart';
import 'package:latlong2/latlong.dart';

final reports = [
  FleetReport(
    vehicleId: 'V-001',
    position: const LatLng(35.050, 137.250),
    timestamp: DateTime.now(),
    condition: RoadCondition.snowy,
  ),
  FleetReport(
    vehicleId: 'V-002',
    position: const LatLng(35.052, 137.252),
    timestamp: DateTime.now(),
    condition: RoadCondition.icy,
  ),
];

final zones = HazardAggregator.aggregate(reports);

for (final zone in zones) {
  print('${zone.severity.name}: ${zone.vehicleCount} vehicles');
}

Integration Pattern

fleet_hazard usually lives between a telemetry stream and a map overlay. Collect reports from your provider, aggregate them into zones, then render the zone summaries in whatever map widget or overlay layer your app uses.

import 'dart:async';

import 'package:fleet_hazard/fleet_hazard.dart';
import 'package:flutter/material.dart';

class HazardSummaryList extends StatefulWidget {
  const HazardSummaryList({
    super.key,
    required this.provider,
  });

  final FleetProvider provider;

  @override
  State<HazardSummaryList> createState() => _HazardSummaryListState();
}

class _HazardSummaryListState extends State<HazardSummaryList> {
  final reports = <FleetReport>[];
  StreamSubscription<FleetReport>? subscription;

  @override
  void initState() {
    super.initState();
    subscription = widget.provider.reports.listen((report) {
      setState(() {
        reports.add(report);
      });
    });
    widget.provider.startListening();
  }

  @override
  void dispose() {
    subscription?.cancel();
    widget.provider.stopListening();
    widget.provider.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    final zones = HazardAggregator.aggregate(reports);

    return ListView(
      shrinkWrap: true,
      children: [
        for (final zone in zones)
          ListTile(
            title: Text('${zone.severity.name} zone'),
            subtitle: Text(
              '${zone.vehicleCount} vehicles • '
              '${zone.radiusMeters.toStringAsFixed(0)}m radius',
            ),
          ),
      ],
    );
  }
}

In a full navigation UI, this same zones list is what you would pass to a map overlay layer so the driver sees clustered snowy and icy segments, not raw per- vehicle noise.

Implement a provider

class MyFleetProvider implements FleetProvider {
  @override
  Stream<FleetReport> get reports => _controller.stream;

  @override
  Future<void> startListening() async {
    // Connect to your telemetry source
  }

  @override
  Future<void> stopListening() async {
    // Stop updates
  }

  @override
  void dispose() {
    // Release resources
  }
}

API Overview

Type	Purpose
FleetReport	Individual vehicle report carrying position, road condition, confidence, and timestamp.
HazardZone	Clustered geographic hazard summary with severity and confidence rollups.
HazardAggregator	Pure Dart clustering algorithm that converts reports into hazard zones.
FleetProvider	Stream-based interface for simulated, local, or remote fleet telemetry sources.
RoadCondition	Canonical hazard labels such as dry, snowy, and icy.

Works With

Package	How
driving_weather	Weather conditions correlate with fleet-reported hazards
map_viewport_bloc	Hazard zones render at Z3 in the viewport layer stack
driving_consent	Fleet data sharing requires explicit consent

See Also

• driving_conditions — Road surface and safety scoring
• navigation_safety — Safety alert overlay
• kalman_dr — Dead reckoning through GPS loss

Part of SNGNav — 11 packages for offline-first navigation on Flutter.

License

BSD-3-Clause — see LICENSE.