By the outbreak of World War Two, over 300 trains crossed the viaducts each day following the strategically important Ruhr-Hannover-Berlin route.
The Hamm-Wunsdorf section of the line (with Bielefeld in the centre) carried the heaviest tonnage of freight anywhere in Germany.
Bielefeld itself was a medium sized industrial town producing an impressive range of important war material. The business of Dürkopp was the fifth most important company in the German Reich. This company and other smaller businesses produced handguns, machine guns, grenades, detonators, anti aircraft and anti tank weapons, aircraft gun turrets, parts for radio trucks and most importantly the tracks for tanks and other armoured vehicles.
This impressive inventory made the town an important target for American and British bombers.
Bielefeld also had important railway yards and was a control point for large numbers of Wermacht troops moving between the various front lines.
The general target area and actual viaduct location are marked with circles.
Today Bielefeld is easily accessible from the A2 motorway. Visitors should then follow Bundesstrasse 61 towards Herford.