The calculated distance (air line) between Braine-l'Alleud and Anderlecht is approximately 11 miles respectively 17 kilometers.
By car or train, the actual journey to Anderlecht is certainly longer, as only the direct route (as the crow flies) between Braine-l'Alleud and Anderlecht has been calculated here.
Air line (approximately)
17 kilometers
9 nautical miles