It seems all the streets in the centre of Buenos Aires are one way, alternating. It certainly makes being a pedestrian easier, especially when you’re used to driving on the left. Most intersections don’t have lights and rely on everybody being considerate – cars, pedestrians, motorcycles and bicycles. When it’s not so busy (i.e. the middle of the night) cars and buses pick up speed and toot when approaching an intersection, which I believe means they intend to keep barreling through and anyone else in the vicinity should give way. Seems to function quite well, even if it wakes me up at 3am.