Tunnels are more economical than open cuts beyond certain depths
?In the most congested urban area, underground railways or highways is
 the best alternative to provide means of transportation.In case of aerial warfare and bombing of cities, the tunnels would grant better protection as compared to bridges
?Tunnels allow rapid and unobstructed transport facilities in big congested cities.Tunnels prove to be cheaper than bridges or open cuts to carry public utility services like water, sewer and gas
?if tunnels are provided with easy gradients, the cost of hauling is
 decreased
?Tunnels protect the system (railway track, highway, sewer line or oil line etc.) for which it is constructed from weather effects such as snow, rain etc.??????????