 In 1918, the Twin Peaks Tunnel was opened, facilitating the construction of new suburbs and development.Muni Metro ran comprehensive train services through the tunnel that led out to the surrounding regions, including West Portal and Ingleside Terraces, allowing the public to finally gain easy access to the area.The tunnel also reduced travel time into downtown San Francisco dramatically, from almost an hour down to just twenty minutes; from this, the notion of the commuter suburb was born.