Aarhus Parking Availability

The application provides real-time information on availability of parking spots at car parks in Aarhus. When the users location is available, travel times and distances to the car parks are given. In addition information is provided on departing public transportation options from each car park in the near future. Prior to this project I've had no experience with Node.js, and only basic knowledge of Javascript, so I've used it as a way to get more experience in both.

Data Sources

Data is used from the following sources:

• Real-time information on availability in car parks is retrieved from Open Data Aarhus. This provides, for each car park, the current number of parked cars and the total capacity. The numbers are updated every 5 minutes.
• Real-time information on departing public transportation. This is retrieved from the open API of Rejseplanen. Two services are used, one for retrieving stops close to a locations, and one for retrieving departures at the stops.
• Travel time and distance information, from the location of the user to each of the car parks, is retrieved through Googles distances-matrix service, through the use of a node.js module.

Usage

The application is available at http://parking.thorprentow.dk. It shows a map of Aarhus, with a marker for each of the car parks. Each marker shows the current availability through a fill level and a color.

• Hovering above a marker shows the name of the car park, and the current and total number of parking spaces.
• Clicking a marker opens an info window, which shows information on departing public transportation at stops close to the car park.
• When user location is available, a car marker will show at the users location. Clicking this marker will open an info window, which shows a list of travel times and distances to each of the car parks.

Pictures of usage

Deployment

Requires:

• Node.js installation with npm

Steps:

    npm install
    node index.js

Configuration

The application is configured through the config.js file.

Backend

The backend is build on the Node.js platform and the Express web application framework.

The source is available in /lib.

Testing

The application uses the Mocha framework for testing, with mockery for stubbing.

Run all tests using the 'mocha' command.

Test code is available in /test.

Logging

The application uses log4js for logging. Logging can be configured in log4js.config

Web services API

The application exposes three HTTP REST webservice interfaces. Results are JSON formatted.

GET /parking

Returns a JSON array with information on car park availability in the following JSON format:

[
    {
        "name" : string,
        "coords" :
        {
            "lat" : float,
            "lng" : float
        },
        "capacity" : int,
        "count": int
    },
    ...
]

Example

The service is implemented mainly in AarhusParkingRetriever.

GET /stops?lat=[float]&lng=[float]

Returns information on departing transportation from stops in the configured vicinity of the given (lat,lng) location in the following format. If no stops are nearby, return code is 404.

{
    "stopnames" : ['stopname1','stopname2'...],
    "stops" : {
        "stopname1" : [
            {
                "name" : string,
                "stop" : string,
                "time" : string,
                "direction" : string
            },
            ...
        ],
        "stopname2" : ...
    }
}

Example

The service is implemented through NearbyStopsRetriever and StopConnectionsRetriever.

GET /distances?lat=[float]&lng=[float]

Returns travel time and distance information from the given (lat,lng) position to each of the car parks. The resulting list contains information only for those car parks for which travel times and distances could be computed. Thus the list may be empty if, e.g., an ocean is in the way.

[
    {
        "distanceText" : string,
        "durationText" : string,
        "distance" : int(m),
        "duration" : int(s),
        "name"
    },
    ...
]

Example

The service is implemented mainly in DistanceRetriever.

Frontend

The front end uses the Google Maps javascript API to visualize the data on a map. The code is available in /public.

When the page is loaded, the /parking service is called to draw markers and parking availability. When a car park marker is clicked, the /stops service is called in order to retrieve information on departures, which is shown to the user in an info window.

When the page is loaded, the users location is requested. If this is retrieved, a car marker is drawn to show the users position. If this marker is clicked, the /distances service is called, in order to retrieve information on the travel times and distances to the car parks from the user location. The user is informed of these in an info window.