Tiemme Spa bus company takes care of the connection Florence-Siena with two buses: a rapid line (131R) that takes 1h 15′ and an ordinary line (131O) that takes 1h 35′. The terminus in Florence is in Via Santa Caterina da Siena 15, near the train station Santa Maria Novella.
One-way ticket Firenze-Siena costs € 7,80 (€ 12,00 on board). Weekly ticket costs €34,80.
Download here pdf timetables:
– Ordinary line
131 A Siena – Colle Val D’Elsa – Poggibonsi – Florence (valid since 11 June 2016)
131 R Florence – Poggibonsi – Colle Val D’Elsa – Siena (valid since 11 June 2016)
Liscio bus company offers a line Siena Firenze:
Line Potenza Siena Firenze timetables
Versione italiana: Firenze Siena autobus