Timetable for the usual train itinary (Cortina - Calalzo by bus):
Cortina d'Ampezzo dp 6.25 - Roma Termini ar 14.10, (change at Calalzo, Belluno and Padova)
Cortina d'Ampezzo dp 8.20 - Roma Termini ar 17.10, (change at Calalzo, Ponte, Treviso and Mestre)
Cortina d'Ampezzo dp 11.15 - Roma Termini ar 19.10, (change at Calalzo, Belluno and Padova)
Cortina d'Ampezzo dp 12.10 - Roma Termini ar 20.10, (change at Calalzo, Ponte, Conegliano and Mestre)
Cortina d'Ampezzo dp 13.15 - Roma Termini ar 21.10, (change at Calalzo, Ponte, Conegliano and Mestre)
Cortina d'Ampezzo dp 15.05 - Roma Termini ar 23.10, (change at Calalzo, Pone, Conegliano and Mestre)
Seasonal buses from December 8th-10th and 16th - 31st, except Dec 25th:
Cortina d'Ampezzo dp 10.00, 14.30, 15.30 - Mestre ar 12.30, 16.55, 18.00
Connecting trains:
Mestre dp 13.37, 17.37, 18.37 - Roma Termini ar 17.10, 21.10, 22.10
http://dolomitibus.it/it/linee-extraurbane-estivo
http://www.atvo.it/it-venezia-cortina.html