Return to Vol. 5 Issue 4, September 2010

Where Should We Go? CommonSpace Helps Philadelphians Answer the Perennial Question

By in Vol. 5 Issue 4, September 2010

A preview version of CommonSpace ( made its Philadelphia-exclusive debut on August 13th, just in time for users to plan their attendance at this year’s Live Arts Festival and Philly Fringe. The tool is a collaborative destination discovery and sustainable transit planning web application and is the product of a yearlong collaboration between Azavea and the Sustainable Business Network of Greater Philadelphia, NPower Pennsylvania and the William Penn Foundation.

CommonSpace was an enriching project for Azavea because it enabled us to expand our work in social and technical areas core to the company’s mission. The application’s interactive, real-time transitshed visualization extends the concept underlying theWalkshed project.  It also encourages community-building and sustainability by making it easier for users to have fun while making environmentally and socially responsible transportation choices.  Technically, the challenge of developing a scalable web site that can support complex geoprocessing for large numbers of visitors was also an opportunity to push the limits of our distributed computing technology.

CommonSpace enables users to search for Live Arts Festival and Philly Fringe events and other social activities within an area accessible to everyone in a group of friends

So just what does CommonSpace do? Borrowing from the urban planning concept of a “walkshed”– the area that is accessible to pedestrians within a given time period – the web site enables users to calculate their personal “transportation-shed” or “transitshed” to find activities and events within that area.  A user begins by entering a location, whether they want to walk, bike or take public transit, and the length of time they are willing to travel; the application generates an interactive map of the areas that are reachable given these criteria. If the user adds transitsheds for their companions, the application will identify the areas convenient to all of them: their common space.

A user can then search within this space for activities and locations — dining, shows, cultural events, shopping, and more — and add interesting destinations to a plan that can be shared with friends or be used to generate directions.  Integrating this destination data from feed partners afforded Azavea the opportunity to work with leading regional organizations including the Greater Philadelphia Tourism Marketing Corporation (GPTMC) and the Greater Philadelphia Cultural Alliance (GPCA). By unifying information from blogs, databases, and public listings, CommonSpace demonstrates how geospatial technologies can filter the simultaneously overwhelming and fragmented resources available on the Internet to make them accessible and meaningful.

The platform is built on a combination of OpenStreetMap data and transit data from SEPTA (the Philadelphia regional transit agency), which was recently released in the General Transit Feed Specification (GTFS) format.  To calculate the transitsheds, the system uses the open source GraphServer framework. Once a user selects a starting location and mode of transit, tens of thousands of possible routes are mapped behind the scenes. The result is rendered on a map, and users can move a slider to increase or decrease the time they are willing to travel and see their transitshed grow or shrink accordingly.

DecisionTree logoWithout optimization, the complex geoprocessing required for each user would take too long and require too many computer server resources to integrate into a high traffic website.  As part of our optimization process, we used an experimental, next-generation version of our DecisionTree technology, code-named Trellis, for distributing the geographic data processing across many servers.  Developed using Scala, an emerging programming language with powerful constructs for parallel processing, this new technology enables CommonSpace to remain performant even with many simultaneous users.

CommonSpace will be available during a preview period lasting through October 15th. Where the application goes next will depend on feedback from users like you! Visit to try it out and tell us what features you like or don’t like, how you see yourself using it, and what you’d like added in the future.