Okay, I was wrong - I actually HAVE driven one of these recently. A half version was built at MD 295 @ Arundel Mills Blvd, replacing a two roundabout setup that had only been in place for a few years. I never realized it until I looked at an aerial view just now in response to Norri's question below. I just didn't realize it, because I always take the free right onto MD 295 NB, which bypasses the DDI, and was a free right even when the roundabouts were in place.
Originally Posted by
Norri
Wouldn't two roundabouts achieve the same result without the need for lights?
Apparently, yes, a two roundabout system does the same thing. For some reason, though, the two roundabouts were removed from the MD 295 @ Arundel Mills Blvd interchange when the Maryland Live casino was built a couple of years ago. I don't know whether the DDI handles traffic better or with fewer accidents or what, but apparently the MD State Highway Administration thinks it does.
https://goo.gl/maps/QSMSxbDKzmn