On June 10, 1901, the Main Line Elevated began running through the Tremont Street subway. The platforms at Park Street were retrofitted with raised wooden sections to allow elevated trains to run on the outer tracks to the Pleasant Street Portal, while streetcars continued to use the inner tracks and inner loop, entering the subway from the Public Garden incline. This arrangement lasted until Main Line service was moved to a separate tunnel under parallel Washington Street. Elevated trains last ran through the tunnel on November 28, 1908; they moved to the Washington Street Tunnel on November 30, and streetcar service returned to all tracks on December 4.