Trenitalia Intercity operates a train from Trieste to Treviso every 2 hours. Tickets cost $25 - $40 and the journey takes 2 h 27 min. Alternatively, FlixBus operates a bus from Trieste to Treviso every 4 hours. Tickets cost $8 - $15 and the journey takes 1 h 55 min. TerraVision IT also services this route hourly.
From Trieste Centrale train to Treviso Centrale. 2 h 27 min 29€. From Trieste Centrale train to Venezia Mestre then train to Treviso Centrale. 2 h 27 min 19€. From Trieste bus to Mestre Railway Station then bus to Venice Treviso Airport (TSF). 3 h 1 min 22€. From Trieste drive to Treviso. 1 h 34 min 22€.