The calculated distance (air line) between Grand-Bourg and Pointe-Noire is approximately 40 miles respectively 64 kilometers.
By car or train, the actual journey to Pointe-Noire is certainly longer, as only the direct route (as the crow flies) between Grand-Bourg and Pointe-Noire has been calculated here.
Air line (approximately)
64 kilometers
34 nautical miles