This is a story I got off the internet, it has not been verified. I think it might be true as dogs are intelligent and resourceful. These are the commuting dogs in Moscow who take the underground trains to the streets in the city centre every morning. Reason: they get off at selected stations in the city areas where food scraps are plentiful. In the evenings, they board the public transport to return to their suburbs for a good night sleep.
Observers noticed that they even work in groups helping each other. They "recognise" their stops by gauging the time taken between stops. They are clever enough to select the quieter carriages in the front and end of the trains. I presume they have not been fined for not possessing tickets as it would be difficult to ask a dog where it is getting off.
There is even a theory put forward for this unusual phenomenon. Dr Poiarkov of the Moscow Ecology and Evolution Institute states that the industrial complexes in the city used by the dogs as homes, were moved to the suburbs after the Soviet Union collapsed in 1990s. Thus, the dogs moved together to the suburbs . But, as more food is found in the city, the dogs adapted by taking the trains to the city every day and returning home in the evenings.