crown of the tunnel). A fourth drift was added at the centerline bottom of the tunnel to facilitate drainage of the ground at the western end. The two crews first "holed through" and connected their excavations near Laguna Honda station on April 5, 1917, from the east portal and from the west. Several notable accidents occurred during the construction of the tunnel: A cave-in at the west portal trapped several men in April 1915, killing one A fire broke out in November 1915 Four were killed and several injured while investigating a blasting charge that did not go off when planned in February 1917 A woman's house was nearly blown off its foundation by a blasting charge. Dedication ceremonies were held at each portal on July 14, 1917. Mayor Rolph and several other dignitaries, including former Mayor P. H. McCarthy spoke at the east portal, beginning at 2:00 p.m.; after the remarks, hundreds of people walked through the tunnel to the west portal, and Judge E. P. Shortall was the first of the pedestrians to arrive. At the west portal, Mayor Rolph spoke again and a ceremonial silver spike was driven by O'Shaughnessy and Rolph to mark the start of construction of the Twin Peaks Railway. The inaugural trip through the tunnel occurred on December 31, 1917. The tunnel was opened to revenue service on February 3, 1918, and was the world's longest tunnel for street railway traffic at the time. Mayor Rolph served as the motorman for the first revenue trip, and most of the paying passengers were City Supervisors, wives, and invited guests. The trip through the tunnel took seven minutes. Incorporation into Muni Metro The tunnel was built sloping downwards at the east end, anticipating future expansion to a tunnel under Market Street per Arnold's plan. A technical report was commissioned by the city in 1960 to study possible rapid transit routes. This recommended that the initial line linking BART from a transbay tunnel to Daly City be routed through Twin Peaks Tunnel. BART's 1961 plan did not include the tunnel connection on Market Street. When the Market Street subway was built in the early 1970s, it was connected to the Twin Peaks Tunnel to be used by the K Ingleside, L Taraval and M Ocean View lines. These services were spared from conversion to trolleybus by virtue of their use of Twin Peaks Tunnel. The Eureka