MIAMI -- Each day, dozens of ambulances speed toward Jackson Memorial Hospital. The 12th Avenue bridge is a major north-south artery there -- an artery that is now clogged.

"There's no way for the vehicles to veer off to the side to let a rescue or a fire truck come through and, basically, we get stuck in the middle of this gridlock," Miami fire-rescue spokesman Ignatius Carroll Jr. said.

Miami fire-rescue officials said the gridlock is costing them -- and their patients -- critical response time into Miami's medical hub.

Three hospitals -- Miami Veterans Affairs Medical Center, Cedars Medical Center and Miami-Dade's only trauma center at JMH -- are four blocks from four bridges over the Miami River that are either under construction or closed.

Lanes leading to the 22nd Avenue bridge are closed for construction, as is the 12th Avenue bridge. The 17th Avenue bridge is closed for repairs, and the Seventh Avenue bridge was demolished.

As a result, paramedics are finding themselves boxed in at a time when every second matters.

"We know we have created a major inconvenience into the area," Miami-Dade County Public Works Department spokesman Delfin Molins said.

The county's public works department said it was forced to close the 17th Avenue bridge because truckers continued to exceed the bridge's weight restrictions. But frustrated first-responders, as well as area commuters, wonder why the county and state did not delay the other projects.

"We want to make a change now before we end up losing a life," Carroll said.