Check out this area map from 1971 (courtesy of Steve DePalma’s site http://genetics.med.harvard.edu/~depalma/steve/md/). If you look closely, you’ll see that Olson Street and Raleigh Road don’t connect. Up until that time, there was a foot bridge as the only means of crossing over Barnaby Run creek. Soon after the “tunnels” were put in, allowing Raleigh Road to extend and intersect with Olson Street. Kind of hard to view in most web browsers, so you might want to save the file and open with any image viewer.