The Schnellweg (en: expressway) system, a number of Bundesstraße roads, forms a structure loosely resembling a large ring road together with A2 and A7. The roads are B 3, B 6 and B 65, called Westschnellweg (<answer>B6</answer> on the northern part, B3 on the southern part), Messeschnellweg (B3, becomes A37 near Burgdorf, crosses A2, becomes B3 again, changes to <answer>B6</answer> at Seelhorster Kreuz, then passes the Hanover fairground as <answer>B6</answer> and becomes A37 again before merging into A7) and Südschnellweg (starts out as <answer>B6</answer>5, becomes B3/<answer>B6</answer>/<answer>B6</answer>5 upon crossing Westschnellweg, then becomes <answer>B6</answer>5 again at Seelhorster Kreuz).
What road does the Messeschnellweg pass the Hanover fairground as?
B6