With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Connaught Tunnel is an underground passageway.
text_B: A tunnel is an underground passageway , dug through the surrounding soil / earth / rock and enclosed except for entrance and exit , commonly at each end .. A pipeline is not a tunnel , though some recent tunnels have used immersed tube construction techniques rather than traditional tunnel boring methods .. pipeline. Pipeline transport. immersed tube. immersed tube. A tunnel may be for foot or vehicular road traffic , for rail traffic , or for a canal .. traffic. traffic. rail. rail transport. canal. canal. The central portions of a rapid transit network are usually in tunnel .. rapid transit. rapid transit. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers .. aqueducts. aqueduct ( watercourse ). hydroelectric. hydroelectric. sewers. sanitary sewer. Utility tunnels are used for routing steam , chilled water , electrical power or telecommunication cables , as well as connecting buildings for convenient passage of people and equipment .. people. people. Secret tunnels are built for military purposes , or by civilians for smuggling of weapons , contraband , or people .. smuggling. smuggling. contraband. contraband. people. people. Special tunnels , such as wildlife crossings , are built to allow wildlife to cross human-made barriers safely .
related.