Dublin might be an important capital in Europe, it doesn’t have a highly-developed public transport programme at the moment. I mean, efficient and fast transport methods, like metro/underground or train. The most developed method stays the bus, and actually, it is very sophisticated! You can go anywhere in the capital without too much troubles. However, it will takes time as there are many stops and traffic jam.
The ticket’s price is defined by stop. So you should trust the driver! If you get on the bus and pays a single ticket or just validates your transport card, you will pay the full fare. However, if you plan to get out after a few stops, and not doing the entire bus line, full fare is not worth it. In Dublin, you tell the name of your stop to the bus driver and she/he will do quick maths and tell you how much is the ticket!
Bus as I said earlier, the Liffey cut the city in 2 different sections, North and South. Only bridges allow to cross. There is only a few bridges and they are, most of the time, crowded with cars.
The city owns 2 tram lines. One North. One South. None of them cross the Liffey. Each line connects the areas far from the centre, residential and offices, to the city centre.
When I left in 2017, 2 additional northern lines were about to be finished.
Regarding the validation of your tram ticket, you have to validate your card before get on the tram, but also when you get out! If you don’t, the system will automatically calculate the full fare, and not the travel you just did.
So be very careful when you use the public transportation, especially when you validate your card. If you don’t do it correctly, depending on the transport method, you risk to top-up your card very often, and your budget will explode!
The Leap Card
It is basically a transport card that allows to quickly pay and validate your journeys. Like the Oyster Card in London, Navigo in Paris or MetroCard in NYC. Easy and practical. You top-up your card to the different terminals at the stations, in shops, online, or even with your mobile phone. It allows you to save a few cents in your journeys.