By ship
There are some cruise trips from Koblenz to Trier. However: they are expensive.
By plane
There are several airports in the vicinity with reasonable access to Trier.
Luxembourg Airport is about 50 km away.
Low-cost carrier hub Frankfurt-Hahn is 75 km east of Trier. There are roughly-hourly Flibco (http://www.klikhierniet.nl/) buses, but the bus stop is several km out of town near the Nell's Park hotel.
Frankfurt International Airport is about 200 km away. The train from there would be about 3 hours via Saarbrücken or Koblenz.
By train
Trains leave hourly from Trier to Saarbrücken, Koblenz and Cologne. Timetable and ticket information could found at (http://www.db.de/site/bah...)
By car
Trier is connected by the European motorway E44 from Luxembourg city ~50 km via Trier to Koblenz ~100 km, E422 from Trier to Saarbrücken ~100 km.
Trier is connected to the Autobahn A6. This city is about one hour from Kaiserslautern or two hours from Mannheim.