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