Ilmenau is situated close to the Bundesautobahn 71 to Erfurt in the north and Würzburg/Nuremberg (via A 73) to the south. Near the town, the Autobahn crosses the Thuringian Forest with some of Germany's largest tunnels and bridges. Furthermore, there were three Bundesstraßen connecting Ilmenau: the Bundesstraße 4 to Erfurt in the north and Coburg in the south (annulled after the opening of A 71 during the 2000s), the Bundesstraße 87 to Weimar in the north-east (now starting at the Autobahn some kilometres north-east of the town) and the Bundesstraße 88 to Eisenach in the north-west and Rudolstadt in the east, which was relocated around Ilmenau as a bypass (via the A 71 in the north and on a new line in the east).