I suspect there was more rail activity in the port years ago, when "breakbulk" rather than container freight dominated. FEC's "downtown spur", which I hi-railed two years ago (work related, very official) was once the FEC main to downtown Miami. It's all 10 MPH and unsignaled now, but once was much faster. FEC's Buenavista Yard (now being redeveloped as condos) was only 20 blocks or so north of downtown. There was also a full wye at Little River, where the FEC spur to Hialeah Yard turns west. The south leg remains, although the turnouts have been pulled. it was once double-track.
Improving rail access to the port would require something like building a tunnel -- very expensive. And the Port of Miami, stuck on Dodge Island and surrounded by water, has no place to grow.
As part of a transportation study of southeast Florida, I visited the port of Miami, Port Everglades, and the Port of Palm Beach in 2006. Port Everglades has rail into the port (although the connection to the former SAL is gone, as noted above), and Andrews Ave. container yard is less than a mile from the port. The Port of Palm Beach has an "on dock" rail yard right in the port. Both ports have room to grow. Port Everglades is by far the largest, but the Port of Palm Beach (which is where FEC's car float to Havana used to dock in the 1950s) is growing as well. FEC originates three intermodal trains a day at Andrews, and one from the Port of Palm Beach (which is actually in Riviera Beach).
Bottom line for all Florida ports is that they're out on a peninsula, and so will only ever serve local traffic. Containers headed to SE US locations go through Savannah these days, where they're a whole lot closer to major markets. Problem with Florida is that you go 300 miles north from Port Everglades, and...you're still in Florida.
Randy Resor, aka "NellieBly" passed away on November 1, 2013. We honor his memory and his devotion to railroading at railroad.net.