Traffic Cameras

Traffic Cameras with tile generation, caching, and routing services.

Requirements

Functional Requirements

• Serve map tiles
• Compute routes with traffic

Non-functional Requirements

• Low tile latency
• Accurate routing ETAs

High-Level Design

• Tile builder → store → CDN
• Routing with traffic ingestion

Capacity & Sizing

• Tile RPS, CDN cache size, routing QPS

Key Components

• Tile builder, Tile store, Routing service

Architecture

Data Model

• tiles (z, x, y PK, ts, etag)
• roads (road_id PK, geom, speed)
• routes (route_id PK, start, end, cost)

APIs

• GET /tiles/{z}/{x}/{y}.pbf
• GET /route?from=..&to=..
• POST /ingest { data }

Hot Path

1. GET tile → CDN → origin (on miss)

Caching & TTL

• Long TTL for tiles; purge changed regions

Scaling

• Precompute hot tiles
• Hierarchical caches
• Parallel route search

Trade-offs

• Vector tiles size vs detail
• Realtime traffic vs cost
• Route optimality vs speed

Failure Modes & Mitigations

• Stale tiles → invalidation
• Traffic feed outage → degrade
• Routing timeouts → fallback heuristics

Observability

• Tile cache hit
• Route latency
• Ingest lag