The results are dramatic: Cable barriers have slashed the number of deadly canal crashes on Florida's Turnpike and the stretch of Interstate 75 known as Alligator Alley.
More than $100 million was spent over the last 10 years to make the roads, used by South Florida drivers to get to Orlando and the Gulf Coast, much safer. Before the barriers were designed and installed along Alligator Alley, 14 people died in 56 canal crashes on Alligator Alley from 1995 to 1999.
But from 2007 to 2011, the latest figures available, only two crashes occurred, with one death each.
On the turnpike, a total of 95 vehicles entered canals along the turnpike from 1999 to 2003. After 117 miles of guardrails and barriers were installed, only four vehicles plunged into canals from 2008 to 2012.
But the systems aren't foolproof. Five people, including three children, died when their SUV flipped into a canal along the turnpike near Lake Worth in 2008. A tire blew out, causing the SUV to somersault over the cable barrier.
"Engineering and designing for every driver behavior is not possible, just as accounting for the aerodynamics of every vehicle that leaves the roadway is not possible," said turnpike spokeswoman Christa Deason.
On January 21, a mother and her two children were killed when their car crashed through one of the posts on Alligator Alley that supports the barrier, instead of the tensioned cables designed to stop cars from going into the water.
Officials are reviewing that crash to see if the barriers can be improved.
"Tragically, we have seen situations where the system hasn't worked. But overall it has saved lives," said Florida Department of Transportation spokeswoman Debbie Tower.
The cable barrier system is equipped with strobe lights every 1,500 to 2,000 feet that are connected to a traffic management center in Fort Myers. As soon as a car hits the barrier, the lights on the adjacent posts are activated and an alert is sent to traffic center.
About 51 miles of canal barriers are under construction along the turnpike in Osceola, Lake and Sumter counties. That leaves 20 miles in Orange and Okeechobee counties waiting for construction in 2014 and 2015.
In addition to the canal barriers, medians along the entire 312-mile turnpike from Florida City to Wildwood now have some form of protection, putting an end to most cross-over crashes. The number of head-on crashes dropped by 92 percent after the guardrails were installed.
From 2008 to 2012, the turnpike averaged fewer than seven crossover crashes a year compared to 72 per year from 2000 to 2002, before rails were installed.
One of the biggest improvements took place in Miami-Dade County, which had 42 crossover crashes from 2000 to 2002. The number dropped to seven from 2008 to 2012.
"The dramatic reduction in crashes is a testament to the success of both projects," Deason said.
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