Traffic Tracker

Built to support humanitarian efforts in Nepal, this app collects and aggregates traffic data from GPS traces to easily visualize traffic speed pattern across cities.

Run locally

Install Node dependencies

$  npm install

Set up API keys

This application uses the TrackMatching API to snap GPS coordinates onto roads. You need to get a free API key from their website in order for it to work. Place your App ID and App Key in a file named config.json at the root of the project like so:

{
  "keys": {
    "TRACK_MATCHING": {
      "APP_ID": "YOUR_APP_ID_HERE",
      "APP_KEY": "YOUR_APP_KEY_HERE"
    }
  }
}

Start server

$  npm start

Server is running at http://localhost:3000

Upload GPS traces

Endpoint POST /trip

Include a trip JSON object in the request body:

{
  "trip": {
    "geopoints": [
      {
        "lat": 49.165843,
        "lon": -123.107281,
        "time": "Tue Jun 09 2015 11:31:53 GMT-0700 (PDT)" // JS Date String
      },
      
      ...
    ]
  }
}

Server returns a 200 status code immediately on success, while the request is processed in the background.

Getting traffic speeds

Endpoint GET /visualize

The visualize endpoint gets all speed data from the server using no params. The result is a JSON object:

{
  "status": "success",
  "segments": [
    {
      "_id": "557619b42bba3087b53e5053",
      "aNode": 97998243,
      "bNode": 553101333,
      "way": 74366445,
      "__v": 0,
      "speeds": [
        4.319808545526469
      ]
    },
    {
      "_id": "557619b42bba3087b53e5054",
      "aNode": 253491085,
      "bNode": 553101333,
      "way": 74366445,
      "__v": 0,
      "speeds": [
        4.319808545526469
      ]
    }
  ],
  "nodes": {
    "97998243": {
      "_id": 97998243,
      "location": [
        -123.122786,
        49.2832809
      ],
      "__v": 0
    },
    "253491085": {
      "_id": 253491085,
      "location": [
        -123.1217731,
        49.2826492
      ],
      "__v": 0
    },
    "553101333": {
      "_id": 553101333,
      "location": [
        -123.1222277,
        49.2829285
      ],
      "__v": 0
    }
  }
}

Node

Nodes are points on a map.

_id references OSM node IDs

location are in GeoJSON format: "location": [lng, lat]

Segment

Segments are a roadway between two nodes on an OSM way

aNode and bNode always refers to a node in nodes.

aNode ID is by design smaller than bNode to avoid duplicate Segment entries in the database.

Note: While segments is an array, nodes is a hash with keys that reference to its OSM node IDs for quick searching.

Endpoint GET /visualize/bbox

Specify a bounding box in the query string of the GET request to return only segments covered by the box.

Example

$  CURL "/visualize/bbox/?sw_lat=49.195&sw_lon=-123.27&ne_lat=49.315&ne_lon=-123.020"

Response is in same format as the GET /visualize endpoint.