August 30, 2024
How many known roundabouts are in the state of Washington? Where has Florida implemented multilane roundabouts with a rectangular rapid flashing beacon at the pedestrian crossing? What are some examples of roundabouts built near railroad crossings?
These questions can all be answered using the Roundabouts Database, the most comprehensive inventory of roundabouts and circular intersections on the web.
Kittelson launched the Roundabouts Database as an outgrowth of the research project that created the first edition of the Federal Highway Administration’s Roundabouts: An Informational Guide. In 1997, it was an inventory of 150 roundabout sites. Today, there are nearly 30,000 records in the database. It continues to be managed by its founder, Principal Engineer Lee Rodegerdts—though thousands upon thousands of entries have been contributed by other researchers, practitioners, and roundabout enthusiasts. Our unwavering goal is for the database to be a public service.
The value of the Roundabouts Database goes far beyond knowing that there are more than 10,000 roundabouts in the United States and Canada (as well as a growing number of records in many other countries). As a transportation engineer or planner digs into the database, they’ll find layers of information that can be combined to answer many questions about roundabout types, features, and contexts.
Here are two examples of how the Roundabouts Database can be used to conduct insightful searches.
Search Using Filters
The database’s “Advanced Search” function provides the ability to combine a variety of filters, including roundabout type, lane type, location, size, additional control types, and what the intersection looked like previously, to dig into multiple layers of detail. This link can be found on the “Index” page.
Select the parameters you’re interested in seeing, as well as the geographic scope (if you want to see a specific state, be sure to select both state and country as some state abbreviations will show up in multiple countries).
Clicking “Search” generates a list of results—for this search, 34 records (as of 8/12/24, the date the search was conducted). Click on a result to view an aerial photo in Google and Bing.
But don’t stop there! The results can also be exported as KML files and opened in Google Earth, where further insights can be gleaned. Drop into the street view to look at details up-close, and use the Wayback Machine to see what the intersection looked like before it was converted into a roundabout. You might see clues that identify why a roundabout was needed!
You can also export all results together to generate a map in Google Earth that shows you where the roundabouts are located in relation to one another.
Search Using Keywords
What if you want to learn something beyond the filtering options? For example, roundabouts that have been constructed near schools?
Using the Advanced Search once again, plug in any filters you want to use, and enter a keyword in the “text search” box.
The results you get will be all records in which this word shows up in the location name or description. In this case, we searched for all records in the United States with the word “school” in them. Of course, it will take a manual review to confirm the legitimacy of all results—perhaps there’s a site on Pitt School Road or other “School” street somewhere that is not actually located along a school!
As you can see from the descriptions, the results shown here support the intent of the search.
Adding Records to the Roundabouts Database
The Roundabouts Database has evolved into the massive archive it is through the contributions of many volunteers who, in addition to Lee, upload the details and locations of known roundabouts. See a location where the database is missing a roundabout you know of? Send it in!
When you double click on the map view, a box will pop up with instructions for submitting the entry. You must have a login to add records to the database, and can request one by emailing roundabouts@kittelson.com. Alternatively, if you’d just like to make one suggestion and don’t desire an account for future submissions, you can send the contents of your suggestion to that same email address.
If you haven’t already tapped into the benefits of the Roundabouts Database, we hope it proves to be a valuable tool for your future projects! You can peruse more roundabout-related content through the links below:
What’s New in the New Roundabout Guide?
How Many Roundabouts Are in the United States?