005. Salesforce Transit Center, San Francisco

This central public transportation hub has a light-filled, vibrant and inviting atmosphere thanks to light columns – a structurally expressive skylight and walkable glass floor combination that brings sunshine into the building. This innovative solution has met the most demanding requirements for a fire-rated glass floor and skylight to date; 2-hour fire rating, blast, and seismic resistance, plus live loading for foot traffic. It involves horizontal fire-rated glass, structural glass, and spacers with air-gaps to avoid replacing glass due to dirt and condensation issues that would develop with foot traffic and the outdoor environment.