Using Maps to Optimize School Decisions with DiscoverBPS

Andres — Thu, 22 Dec 2011 20:48:00 +0000

This is a guest post by Joel Mahoney, a 2011 Fellow at Code for America. Joel worked with the City of Boston on projects related to public education.

Every year in Boston, parents navigate the school selection process in an effort to get their kids into the best possible public schools. The process is complicated, and, depending on the outcome, can leave parents feeling frustrated and confused. DiscoverBPS was designed to make the process more intuitive, and to help parents make better choices for their kids.

Iteration #1 - Geocoded Addresses
In our first iteration, we used a home address and grade level to identify a student's eligible schools, and then displayed the results on a map. In the screenshot below, the green circle represents the student's "walk zone" (in this case, a 1.5 mile radius appropriate to a 7th grade student), the yellow polygon represents the North Assignment Zone, and the markers represent the schools.

With a little help from Google's Geocoding and Maps APIs, we seemed to be well on our way!

On closer inspection, however, we noticed one school that fell just outside of the walk zone boundary, even though – after zooming in and switching to satellite view – the school campus was clearly overlapping with the walk zone:

Obviously, if our goal was to build a tool to make the process more intuitive, we needed to avoid introducing new ambiguities into the system.

Iteration #2 - School Parcel Shapefiles
To solve the overlap issue, we obtained shapefiles for all of the City's school properties, and used a PostGIS-enabled database to calculate distances between the home address and the nearest point on the school parcel. In so doing, we were able to calculate walk zone distances, which allowed us to properly identify schools with walk zone eligibility:

After a several weeks of deep-diving into the internals of PostGIS mapping, we seemed to be back on track.

Stepping back, however, a new consideration came to light: was it fair to assume that a 7th grader could walk from downtown Boston, across the Charles River, and to a school in Charlestown in less than 1.5 miles? A Google Directions search suggested otherwise (the route below is estimated at 1.9 miles):

If the purpose of the walk zone policy was to determine which schools a student could reasonably get to on foot (and to discourage parents from busing their kids to schools on the other side of town), our walk zone circle began to seem misleading.

Iteration #3 - Walkshed Mapping
In the end, we decided to use an open source project called pgRouting (which extends PostGIS to provide geospatial routing functionality) along with OpenStreetMap to derive a "walkshed" polygon and to calculate street walking distances. We also could have used the Google Maps Distance Matrix API to calculate walking distance, but opted to go with pgRouting based on the need to create the walkshed polygon. These tools allowed us to then visualize the walkshed in Google Maps:

Aside from being noticeably smaller than the walk zone circle, the walkshed conveys a representation of walkability that is customized to the home address. Notice how the walkshed area is confined by bodies of water that are not spanned by any bridges.

DiscoverBPS is now live at www.discoverbps.org. The walkshed map (which would require policy changes by Boston Public Schools) is being considered for use in 2013.

Four Tips for Improving Your Mobile Web Map App

Andres — Wed, 30 Nov 2011 16:30:00 +0000

We've had several new feature announcements for the Google Maps API in the last few months, including high resolution static maps, the new Street View Image API, and the use of high DPI map tiles in the JS Maps API on mobile devices. I'm here to give you some tips for using these new features to improve your existing mobile JS map app .

Upgrade Your App to Use the v3 API
If you're still using the v2 Google Maps API it's time to change that. Period. This is one of the best improvements you can make to your map app. The v3 Google Maps API was designed for the mobile web and it is significantly faster than its predecessor. Not only is the v3 Google Maps API designed to load fast on mobile browsers, but your app will be upgraded immediately because your map will automatically access high DPI map tiles, which have better on screen fidelity.
Use the Static Maps API to Improve User Experience
Check your Google Analytics data (or server logs ) to see if your app is being accessed by devices with browsers that can't or don't fully support JavaScript. You can add logic to your app (e.g, server-side user agent checking) to determine whether you should serve your JS Maps API-based app or a static map image that shows the same or similar information. Although your users won't be able to interact with the map, they'll appreciate the ability to view the map. You can even add markers and other features to the static map . You'll also be able to take advantage of the high resolution Static Maps API.
Use StreetView Images to Provide More Context
Chances are your map app gives users access to all kinds of information, whether it's your own data and images or our very own Places API. Give your users some additional context by using the Street View Image API to provide a general idea of what a location looks like at street level. When you provide a location in your URL request, the API will snap to the panorama photographed closest to that particular location.
Use the JS Maps API Only When It Makes Sense
If all you need is a small map for context, you should be using the Static Maps API. This may seem obvious, but we've come across a few mobile apps that seem to use the JS Maps API to provide nothing more than a thumbnail. Use the Static Maps API to load a small image and, if needed, link that thumbnail to open up a larger map (whether your own page that uses the JS Maps API or maps.google.com).

And again, if you're still using the deprecated v2 Google Maps API in any of your apps (mobile or otherwise), it's time to migrate your app to the v3 Google Maps API, as we're more than halfway through the three year deprecation period.

Posted by Andrés Ferraté, Developer Relations, Google Maps API

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Using Maps to Optimize School Decisions with DiscoverBPS

Four Tips for Improving Your Mobile Web Map App