Construction crews are busy safe-proofing the PortMiami tunnel connecting Dodge Island, where the port is located, to Watson Island.
"If we're 120 feet below sea level, and God forbid anything should happen," said Christopher Hodgkins with Miami Access Tunnel. "All the wall, right from the pavement, all the way through will be fireproof coating."
Crews decided to fireproof the concrete after a tunnel fire in the Alps in 1999.
"This is actually something new that they are undertaking. No one thought you had to fireproof concrete before that," said Hodgkins.
Jet fans installed on the tunnel ceiling will control the air flow 120 feet below Government Cut.
"These jet fans can reverse the airflow to whatever way is going to be safe for anyone that's in the tunnel," said cross passage foreman Joe Toal.
Five cross passages span the width of the tunnel and will be used for emergency evacuations. The excavator to create them is run by remote control.
"It's safer being wireless remote control so nobody's got to be in there," said Toal.
Before crews could cut into the 12-ton tunnel segments, the porous layers of sand and limestone they hold back had to be grouted and frozen solid.
"It's 30 degrees below zero," said Hodgkins. "We cut our way through the concrete."
Floodgates will make the tunnel waterproof.
"We actually have steel gates that come down and seal the tunnel water tight," said Hodgkins.
Project managers hope to open the tunnel in May 2014.