I am also a light sleeper. I lived in the centre of the city for almost three years. I used to get woken up at all hours. I started off with earplugs, but those hurt my ears. Eventually I started shutting my windows and curtains and putting a powerful fan on and it really works well.
Edit: a bonus one gets with the fan is that it also cools you off during summer when a shut window might have caused problems otherwise. (Aircon is uncommon here.)
Yes, when I lived on Powell street in SF (right on the cable car tracks) ear plugs were essential but they can become a crutch too. I've also come to the same conclusion as you about having a fan in the room.
Edit: a bonus one gets with the fan is that it also cools you off during summer when a shut window might have caused problems otherwise. (Aircon is uncommon here.)