 During September 1997, construction of the tunnel commenced.The local geography and location of the tunnel posed some challenges to the construction effort, such as the need to avoid impacting nearby urban development, as well as little cover being available at key areas.Boring operations through the rock incorporated both the use of a tunnel boring machine (TBM) along with some conventional techniques, such as blasting, soil injection, and pipe arches amongst other auxiliary construction measures intended to reduce the risk of excessive settlement.