Salzburg is a medium-sized town in the center of Austria, very close to the border to Germany. It has direct motorway connections to Vienna, Munich and Slovenia. Most of the traffic between southern Germany and Austria passes Salzburg.
Heading west (Munich) or east (Linz, Vienna)
When you want to go over the A1, no matter which direction, you should go to the onramp "Salzburg Mitte" at the B155 ("Münchener Bundesstraße"). There is a lot of traffic and enough place to be seen and for cars to stop. From the town center it's 20-30 minutes walking.