The calculated distance (air line) between Ma Tau Wai and Tuen Mun is approximately 15 miles respectively 24 kilometers.
By car or train, the actual journey to Tuen Mun is certainly longer, as only the direct route (as the crow flies) between Ma Tau Wai and Tuen Mun has been calculated here.
Air line (approximately)
24 kilometers
13 nautical miles