Lisbon train network is managed by the Comboios de Portugal. It is very efficient, with fast and comfortable trains. They represent the most practical and the cheapest way to move in the surrounding.
There are four lines:
Single tickets and 10 tickets carnet for the urban train network can be charged on the 7 Colinas and Viva Viagem cards, while for all other kinds of travel cards and integrated tickets you will need an appropriate CdP card or the Lisboa Viva card.
Buses represent the cheapest way to move around the country. There is not just one national company, but numerous private companies, covering almost the entire territory, with frequent and comfortable vehicles. The bus service is always preferable respect to trains, as they are slow and not very frequent, especially regional trains, while the Alpha Pendular may be faster, but very expensive too. A good alternative is represented by the Intercity trains, just a bit more expensive than buses.
There are 3 big bus stations in Lisbon: Rodoviária, Gare do Oriente (Vermelha line of the underground) and Sete Rios (Azul line), all headed to the north of Portugal, while the bus terminals in Praça de Espanha and Campo Grande serve the southern part of the country.
The train network of the Comboios de Portugal is not very well developed, and both regional and interregional trains are quite slow. The recent introduction of Alpha Pendular trains has partly compensated the lack of railway connections, but the high cost of this service discourages from use. A halfway solution is represented by the intercity trains, which offer a good relationship between quality and price, especially on long distance routes.
Here is a comparative example between bus and train service:
Bus: a one way ticket Porto-Lisbon, with departure every hour and approximate journey time of 3 h ½ costs Euro 17,50;
Train: Intercity train, one way ticket with departure every two hours, approximate journey time of 3h costs Euro 19,50 in second class and Euro 28,50 in first class.
With the Alpha Pendular train (departure every hour), journey time 2 h and 35', price Euro 27,50 in second class and Euro 39,50 in first class.