The calculated distance (air line) between Castanheira do Ribatejo and Barreiro is approximately 23 miles respectively 38 kilometers.
By car or train, the actual journey to Barreiro is certainly longer, as only the direct route (as the crow flies) between Castanheira do Ribatejo and Barreiro has been calculated here.
Air line (approximately)
38 kilometers
20 nautical miles