When the Transbay Transit Center was conceptually designed in 2004, it included a double-deck elevated bus ramp to connect the new terminal into the Bay Bridge.   This massive structure was presumed necessary in order to separate conflicting inbound and outbound bus movements.

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During schematic design, Greg was tasked with investigating whether a single-deck ramp would be feasible while meeting the design capacity of 300 buses per hour, and also enabling some buses to turn around without entering the terminal.  Using the VISSIM traffic simulation software platform, Greg invented a hybrid crossover/turnaround intersection that could accommodate all bus movements using only a single deck and a simple two-phase traffic signal.  

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The bus agencies were initially skeptical of the design, but following two live simulations using buses and cones in a parking lot, they were convinced.  Greg's redesign substantially reduced the aesthetic and shadow impacts of the bus ramp structure while saving $20 million on the project cost.  Other notable design features of the bus ramps include a cable-stayed suspension bridge connecting into the terminal, and a beer garden beneath the turnaround.  The ramps are now under construction and opening in 2018.