The calculated distance (air line) between Venlo and Alphen aan den Rijn is approximately 83 miles respectively 134 kilometers.
By car or train, the actual journey to Alphen aan den Rijn is certainly longer, as only the direct route (as the crow flies) between Venlo and Alphen aan den Rijn has been calculated here.
Air line (approximately)
134 kilometers
72 nautical miles