Eighty-foot-high portals stand like ancient monoliths midway down the causeway that connects downtown Miami to Miami Beach. The soaring portals are not mere architectural follies, however. They were designed to contain and conceal a set of mechanized floodgates that can be lowered during a hurricane emergency to block the entries to the two 4,200-foot-long tunnels. A graphic treatment of bas-relief lettering breaks up the monotony of the cast-concrete facades with variations of the Latin word for “navigate” — navigo, navigas, and navigatis — and this further underscores the maritime nature of the project. The letters are deeply set into the concrete surface and catch sunlight within their chiseled cavities. The narrow sides of the portals are open to reveal bands of orange metal mesh and are back lit to create the impression of volcanic action splitting the portals from within. At night, the openings cast an enigmatic orange glow across the concrete facades.
The graphic treatment continues inside, with colorful, cartoonlike murals that depict sharks, swamp grass, and sea turtles in an underwater narrative — a kind of high-speed animation up and down the walls of each tunnel. The shades of aquamarine, purple, green, and yellow grow darker as the roadway dips farther under the water, and then lighten as the roadway rises to the surface again. Running human figures, painted in black, show where the emergency exits are located.
In addition to tunnel interiors and concrete portals, ArquitectonicaGEO developed an extensive landscaping plan for all approach roads, ramps, drainage swales, and meridians. A six-acre buffer area that surrounds the tunnel entrances was designed to echo the natural ecosystem of Biscayne Bay and the not-too-distant Everglades.