Fetch live transit data¶

In this section you'll learn what GTFS is and how to make a request to the Société de transport de Montréal's Realtime API using Python.

What is GTFS?¶

The General Transit Feed Specification (GTFS) is an open standard for transit data. It means different organizations can publish their transit data in a standard format that software applications can consume.

There are two specifications:

• GTFS Schedule — static data like routes, stops, and timetables
• GTFS Realtime — live updates on vehicle positions, trip updates, and service alerts

GTFS Realtime feeds¶

GTFS Realtime provides several feed types:

• Vehicle positions — where vehicles are right now
• Trip updates — delays, cancellations, and schedule changes
• Service alerts — disruptions and detours

Get an API key¶

To access realtime data from a transit organisation, you'll generally need an API key. To get a key for STM Realtime data, sign up at the STM Developer Portal.

Then:

1. Sign in and create a new application following the instructions in the Wiki guide
2. Add the Données Ouverte iBUS - GTFS-Realtime (v2.0) API to your application
3. Go to Applications, select your app, and find Authentication & Credentials
4. Copy your API key

Your first request¶

Open the transit-dashboard directory in VS Code or your preferred editor.

Set your API key¶

First, set your API key as an environment variable:

export STM_API_KEY="<your-api-key-here>"

$env:STM_API_KEY="<your-api-key-here>"

Write the code¶

Create a file called first_request.py and add the following code:

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import os
import requests

URL = "https://api.stm.info/pub/od/gtfs-rt/ic/v2/vehiclePositions"
headers = {
    "accept": "application/x-protobuf",
    "apiKey": os.environ["STM_API_KEY"],
}

response = requests.get(URL, headers=headers)
print(f"Status: {response.status_code}")
print(f"Content length: {len(response.content)} bytes")
print(f"First 100 characters: {response.content[:100]}")

• Lines 1-2: Import required modules (os and requests)
• Line 4: Define the API endpoint URL. This comes from the STM developer portal (it is displayed in APIs > Données Ouverte iBUS - GTFS-Realtime (v2.0) > Specs > Positions).
• Lines 5-8: Create headers dictionary with accept header and the API key loaded from environment variable
• Line 10: Make a GET request to the endpoint and store the response in the response variable
• Lines 11-13: The response variable is a Response object. Print its status code, content length, and the first 100 characters of the content.

Run it¶

In your terminal, run the code with:

python first_request.py

You'll see output like this:

Status: 200
Content length: 58163 bytes
First 100 characters: b'\n\r\n\x032.0\x10\x00\x18\xd2\xa9\xd9\xd2\x06\x12b\n\x0539076"Y\n%\n\t301233716\x12\x0811:14:00\x1a\x0820260714*\x02320\x0...

• Status 200 means the request was a success.
• The first 100 characters are Protocol Buffer data, not readable text. That's normal — you need a library to parse it into something human-readable.

Congratulations, you've made your first request to a GTFS Realtime API and received live transit data! Next, you'll learn how to parse the response into readable vehicle positions.