Connecticut Avenue was widened in the late 1920s, and increased traffic in the neighborhood caused a great deal of congestion in the circle, making it difficult for pedestrians to get around. Medians were installed in 1948, in the circle, to separate the through traffic on Massachusetts Avenue from the local traffic, and traffic signals were added. In 1949 traffic tunnels and an underground streetcar station were built under the circle as part of the now-defunct Capital Transit project. The tunnels allowed trams and vehicles traveling along Connecticut Avenue to pass more quickly past the circle. When streetcar service ended in 1962, the entrances to the underground station were filled in and paved over, leaving only the traffic tunnel.