Query: Which motorway is Thuringia's most expensive?
Context: The A71 crosses the Land in southwest-northeast direction, connecting Würzburg in Bavaria via Meiningen, Suhl, Ilmenau, Arnstadt, Erfurt and Sömmerda with Sangerhausen and Halle in Saxony-Anhalt. The crossing of the Thuringian Forest by the A71 has been one of Germany's most expensive motorway segments with various tunnels (including Germany's longest road tunnel, the Rennsteig Tunnel) and large bridges. The A73 starts at the A71 south of Erfurt in Suhl and runs south towards Nuremberg in Bavaria.