After the Second World War Diegem was cut through by roads. From 1969 the 1950 roundabout gave way to a huge interchange 360 metres across: below, the link between the E5 and E10 via the Brussels Ring; above, the motorway to the airport, with cloverleaves to the Woluwelaan. The Haachtsesteenweg was given a straight course towards Haren again, so that the old bend around the Wezembeek estate disappeared. For the inhabitants there were a pedestrian tunnel to Diegem-Lo, a bridge in the Lodewijk Degreefstraat and a link to the old Haachtsesteenweg, but the Schetsstraat, Dilsstraat, Machelenstraat, Broekstraat and Molenstraat became dead ends. Brussels got a ring road; Diegem was cut to pieces by it.
The proximity of the airport brought an industrial park on both sides of the Evere-Zaventem motorway, and from July 1971 three hotels opened there, Holiday Inn, Novotel and Sofitel, with more than 600 overnight stays a day between them. There was nuisance too: for years the fumes of a pharmaceutical firm near the water tower, and in 1974 a planned asphalt plant on the Feldheimlaan, which the environment committee managed to stop. Around 1972 the market square was given two-coloured paving and a small round square in front of the castle towers to save the trees. In 1971 a shared television mast was put on the church tower.