Coming from Munich take the A92 motorway via Deggendorf and leave it at the Moosburg-Nord exit.
Coming from Nürnberg take the A9 motorway via Munich, change at the Eching-Ost junction to the A92 motorway via Deggendorf and leave it at the Moosburg-Nord exit.
Continue on the B 11 ordinary road via Deggendorf / Hofham to Landshut.
Near Trausnitz Castle there are 100 parking places for cars and 4 parking places for coaches available ("Hofgartenparkplatz").
On https://stadtplan.landshut.de a map of the town with several search functions is available.
Information on the railway you can find on www.bahn.com.
From Landshut station take the bus number 3 or 6 to "Altstadt", then number 7 or 7A to "Kalcherstraße" (from there it is a walk of around 1 km to the castle). From March to October the busses number 7 and 7A stop at "Hofgartenparkplatz" (800 m from the castle) on demand. Please inform the bus driver if you would like to get off there.
Information on bus timetables and fares is available on www.stadtwerke-landshut.de.