Changes

If you don't mind to take a train, take the regional one towards Ilmenau. Get off in Geraberg (40 minutes ride, ~5€, only once per hour) and follow "Bahnhofsstraße" in direction city center to it's end. Turn right on "Arnstädter Straße" and then the second left on "Talstraße". After passing the last house to your right, turn right and walk the field path approximatly ten minutes to the gas stations "Thüringer Wald Nord". On your way you'll cross beneath the Autobahn.

Take tram number 2 from the city center to the commercial fairground and exhibition center [http://www.messe-erfurt.de/ Messe Erfurt] to the stop 'mdr/kinderkanal' or 'messe', walk over 'Gothaer Straße' to the 'Real' supermarket and ask drivers standing at the traffic light.