获取莫斯科全城拥堵系数：API选型及计算方法技术问询

Hey there, let's break down your questions about calculating and retrieving Moscow's overall traffic jam factor (JF):

1. Does HERE API have an endpoint for direct city-wide jam factor? #

Nope, HERE's Traffic Flow API (the traffic.api.here.com/traffic/6.1/flow.json endpoint you're using) only returns segment-level JF data. There's no built-in endpoint that aggregates this into a single city-wide JF value. You'll need to compute it yourself using the segment data they provide.

2. How to calculate city-wide JF using HERE's existing data? #

The key issue with simple averages or RMS is that they treat every road segment equally—short side streets have the same weight as major highways, which skews the result (since highway congestion impacts overall city traffic far more). Instead, use a length-weighted average:

Here's the formula to implement:

Overall Moscow JF = (Sum of (JF_i * Length_i) for all road segments) / (Total length of all road segments in Moscow)

Notes for better accuracy: #

• Filter relevant segments: Exclude closed roads, pedestrian paths, or segments with no traffic data (check the trafficStatus field in HERE's response).
• Prioritize critical roads: If you want to match Yandex's results more closely, you might add extra weight to major arterial roads, highways, and ring roads (since Yandex likely emphasizes these in their city-wide metric). You can identify these using road type tags in HERE's response (look for functionalClass—class 1 is major highways, class 5 is local streets).
• Update regularly: Since traffic changes dynamically, recalculate this value every 5-15 minutes (match HERE's data refresh rate).

3. Other APIs for Moscow's jam factor #

Since Yandex doesn't expose a backend endpoint for this, here are some alternatives:

Commercial APIs #

• TomTom Traffic API: Provides segment-level flow data with JF-like metrics (currentFlow vs freeFlow speeds). You can apply the same length-weighted average method to get a city-wide value. They offer pay-as-you-go pricing which is scalable.
• Google Maps Roads API: While it doesn't return direct JF, you can combine speed data from the Roads API with free-flow speed estimates (from OpenStreetMap or Google's own data) to compute congestion ratios, then aggregate similarly.
• Mapbox Traffic API: Delivers real-time traffic speed data for road segments. You can calculate congestion as (freeFlowSpeed - currentSpeed)/freeFlowSpeed to get a JF equivalent, then aggregate with length weighting.

Free/Open Options #

• Moscow Government Open Data Portal: Check for official traffic statistics—some cities publish aggregated congestion metrics for major roads. You'll need to navigate the Russian-language portal, but it's a reliable local source.
• OpenTraffic: A community-driven project that aggregates traffic data from various sources. While data quality might not match commercial APIs, it's free and can be used for non-critical applications.

内容的提问来源于stack exchange，提问作者Иван Ерёмин