The calculated distance (air line) between Sv. Trojica v Slov. Goricah and Sežana is approximately 113 miles respectively 182 kilometers.
By car or train, the actual journey to Sežana is certainly longer, as only the direct route (as the crow flies) between Sv. Trojica v Slov. Goricah and Sežana has been calculated here.
Air line (approximately)
182 kilometers
98 nautical miles