Photo by cliff1066 on Flickr.

Longfellow Triangle is one of many lightly used, leftover spaces on the L’Enfant grid. With some creative thinking, the city could turn it into a more useful and enjoyable public space.

The triangle is bounded by Connecticut Avenue, Rhode Island Avenue, 18th Street, and M Street. While it would make sense to have a circle there, one never developed, likely because Rhode Island Avenue ends at the intersections rather than continuing through. The triangle’s mirror image on the grid, where Massachusetts Avenue meets Vermont Avenue, is Thomas Circle.

Currently, Longfellow Triangle is too small to be a useful park, and too isolated by traffic to be a good plaza. Putting a circle there now is impossible, but with a little bit of street reconfiguration it would be possible to make it a bigger and better triangle park.

This is a map of the existing conditions at Longfellow Triangle:

Existing conditions.

Look at how wide the streets are that surround the triangle. Connecticut Avenue is 6 lanes, not counting its generous median. 18th Street is 4 lanes. M Street is 5. All of them have on-street parking, although the parking lanes are used as through lanes at peak periods.

If the city repurposed the parking lanes on each surrounding block and used that width to add to the triangle, the park space could be dramatically enlarged with little reduction in street capacity. On Connecticut Avenue the median could be repurposed as well, or it could substitute for one of the parking lanes.

These images show how that might work. In the left image, parking lanes and the Connecticut Avenue median are identified in red and orange. In the right image, the orange spaces are shifted towards the triangle, and the travel lanes are correspondingly shifted outward.

Shifting the parking lanes towards the triangle would increase usable park space.

The end result would be a considerably larger triangle, one with enough space to begin to take on some of the functions of a true city park. Instead of containing just a row of benches and some shrubs, the space would be large enough for tables, flower beds, and possibly a small lawn. Today’s underused leftover could become tomorrow’s Dupont Circle or Farragut Square.

The down side is that around 30 on-street parking spaces would be lost, and peak period street capacity would drop slightly. This seems a very reasonable price to pay for a greatly enhanced public space.

Other potential complications include the final placement of DDOT’s proposed M Street cycle track and the National Park Service, which is notoriously hard to work with. Neither of these hurdles appears to be a deal breaker, however. The cycle track will only take up a few feet, and if NPS reconfigured Thomas Circle in 2005 they might be willing to reconfigure Longfellow Triangle now.

Obviously this idea would require a considerable amount of additional study before it could be deemed practical. But if it is practical, the upside for urban livability might be tremendous.

Final result: An enlarged park.

Cross-posted at BeyondDC.