If you travel on a bus or subway, you might see a small logo. There are several variants, but the four blue letters is the most widely used. It is the body that regulates public transportation worldwide. The official website is http://www.uitp.org/
The full list of more than 1400 members is here: http://www.uitp.org/all-members and it is growing. Some countries who are fully developed have no UITP members, like the South Korea. The reigning champion is Germany, and I’m surprised that US is relegated far behind. This is good news, too, for the potential member list could increase significantly.
There is an annual event called UITP Summit (https://uitpsummit.org/).
In 2017, the event will take place in Montréal (https://uitpsummit.org/).
In 2015, the event took place in Milan (http://www.uitpmilan2015.org/)
In 2013, there has been a summit in Geneva (https://www.uitpgeneva2013.org/)
UITP has four core values: innovation, expertise, respect, and sharing.