Editing CTrain (section)

=== Further underground infrastructure ===
In addition to numerous tunnels to allow trains to pass under roadways, geographic features, and mainline railways, there are other notable underground portions of Calgary's CTrain system.

Part of the system through downtown is planned to be transferred underground when needed to maintain reliable service. Given this, portions of the needed infrastructure have been built as adjacent and associated land was developed.<ref>{{cite web | author = Calgary Planning Department | title = City Hall Area Redevelopment Plan | version = p. 30 | publisher = City of Calgary | year = 1982 | url = http://www.calgary.ca/docgallery/bu/planning/pdf/city_hall_arp.pdf | archive-url = https://wayback.archive-it.org/all/20080411024523/http://www.calgary.ca/docgallery/bu/planning/pdf/city_hall_arp.pdf | url-status = dead | archive-date = April 11, 2008 | access-date = December 22, 2007 | df = mdy-all }}</ref> As a result of this original plan, when the City of Calgary built a new Municipal Building, it built a short section of tunnel to connect the existing CPR tunnel to the future tunnel under 8th Avenue S. The turnoff to this station is visible in the tunnel on the Red Line entering downtown from the south, shortly before City Hall. However, after [[urban explorer]]s discovered the tunnel and visited it during a transit strike,{{Citation needed|date=May 2009}} the city walled off the spur tunnel with concrete blocks.

As the population of metropolitan Calgary increases and growing suburbs require new lines and extensions, the higher train volumes will exceed the ability of the downtown section along 7th Avenue S to accommodate them. To provide for long-term expansion, the city is reviewing its plans to put parts of the downtown section underground. The current plans allow the expanded Blue Line (Northeast/West) to use the existing 7th Avenue S surface infrastructure. The expanded Red Line (Northwest/South), now sharing 7th Avenue S with the Blue Line, will be relocated to a new tunnel dug beneath 8th Avenue S. The future Southeast/Downtown route will probably enter downtown through a shorter tunnel under one or more streets (candidates include 2nd Street W, 5th Street W, 6th Street W, 8th Avenue S, 10th Avenue S, 11th Avenue S, and 12th Avenue S).  Although Calgary City Council commissioned a functional study for the downtown metro component of the CTrain system in November 2007, the city is unlikely to complete this expansion before 2017 unless additional funding is received from provincial or federal governments. The cost of bringing the potential underground leg under 8 Avenue South could be at least C$800 million, according to Calgary Transit's 30-year [http://www.routeahead.ca/ RouteAhead] plan.<ref name="Extension" /><ref name="Future" />