For London Underground passengers , research suggests that transfers are highly costly in terms of walk and wait times . Because these costs are unevenly distributed across stations and platforms , path choice analyses may be helpful in guiding upgrades and choice of new stations . Routes on the Underground can also be optimized using a global network optimization approach , akin to routing algorithms for Internet applications . Analysis of the Underground as a network may also be helpful for setting safety priorities , since the stations targeted in the 2005 London bombings were amongst the most effective for disrupting the transportation system
2005 London bombings
7 July 2005 London bombings
London Underground