E.T.
I don't think you should mention your transportation issue. If you think the public transport system is good enough, then go with it. But don't make it the potential employers issue. You can easily ask where the position is located without discussing how you'll get there.
Basically it comes down to the fact that there are tons of wonderful qualified people looking for work and you don't want to do anything to make yourself a difficult hire. Any potential problem (transportation, daycare, the fact that you have children and might need to take time off, etc.) will make you a less desirable candidate.