The Mechelse Steenweg is a national road, crossing the railway line from Brussels to Louvain at Kortenberg. The Belgian high-speed train project requires a substantial adaptation of the whole area. In this case, the extension and upgrading from two tracks to two 'normal' tracks on the outside and two central high-speed tracks demanded the replacement of the existing bridges. A long-term interruption of the very busy railway line (with a train passing every 5 minutes) was out of the question, this limiting the construction techniques.