San Francisco's soon-to-be-tallest building got a few design tweaks before it heads back to the Planning Commission for final approval next month. When last we checked in, the Planning Commission compromised with neighbors who were worried they would be left in the dark by the building's long shadow and approved the building's 1,070-foot height. The latest revisions to the building's design will add a new sculptural element the city's skyline and connect street level to the 5.4-acre park planned for the roof of the new transit center with a diagonal elevator.

In the new design, the building's hat stretches the tower 150 feet above the highest occupied floor and now comes with a handsome slit down the middle. Where the previous design gave the illusion of a taller building by extending the glass and steel frame of the lower floors, the latest revision includes perforated steel that will be backlit at night to make the building a more distinct feature of the skyline. As architect Fred Clarke told the Chronicle's John King, "We wanted something visible at urban scale but almost Zen-like in its simplicity... the idea is to further lengthen and slim the profile and also create something more distinctly emblematic of the city." Or, if we'd like to pull a Herb Caen and compare it to another inanimate object, it looks sort of like this fancy, but discreet vibrator.

Closer to the ground, the latest revision includes a small plaza that will connect the tower to the Transbay Transit Center and the urban park that will live 80-feet above street level on its rooftop. A funicular — which is like an elevator, but slanted and much more exciting — will move people from the sidewalk at First and Mission Streets to the park above through a grove of redwood trees. One corner of the tower's base will also be opened up to create a public lobby with seating, shops and an express elevator to the rooftop park. Unfortunately, that clunky sculpture made out of pieces of the old Transbay Center still found its way into the most recent renderings.

Mayor Lee has already signed off on the plan for the Transit Center District, including the environmental study that had all those folks worried about shadows, so the tower only needs final approval from the Planning Commission before developers can start construction in 2013. The hearing is scheduled for October 18th.

Previously: All Transbay Tower Coverage on SFist