After damage to the MacArthur Causeway, boaters and jet skiers may have to slow down

After construction to repair damage on the underside of the MacArthur Causeway caused weeks of traffic headaches in Miami Beach, city officials are considering speed restrictions for motorboats and personal watercraft.

That’s because engineers blame motor-operated water vessels speeding underneath the causeway and shooting saltwater into the air for accelerating the corrosion at the Miami Beach end of the bridge, which required extensive repairs.

“When they go underneath the bridge spans you’ll see that stream of water is going to coat the whole bottom side of the bridge,” said John Bolton, the engineer overseeing the MacArthur Causeway repairs. “It’s that coating with saltwater . . . [that’s] creating this corrosion problem,” he added.

On Wednesday, the City Commission will vote on the creation of “slow speed, minimum wake” zones for motorboats and personal watercraft, such as Jet Skis and Waverunners, near nine bridges including spans on the MacArthur, Julia Tuttle and Venetian causeways. Boat and personal watercraft operators would have to slow down to approximately 5 mph within 300 feet of the bridges to keep their vessels from shooting water high enough to hit the lowest sections.

City officials hope that the restrictions will prevent further saltwater corrosion underneath bridges — as well as the traffic woes caused by bridge repairs.

Miami Beach residents flooded city officials with complaints after the Florida Department of Transportation began a $12.9 million rehabilitation project on the MacArthur Causeway’s East Bridge over the summer. The lane closures required to repair the bridge backed up traffic for blocks, clogging the main artery connecting South Beach to the mainland. The frustration reached such a fever pitch last month that the Miami-Dade County Commission temporarily suspended westbound tolls on the Venetian Causeway during rush hour in order to give Miami Beach residents an alternate route.

“The construction was incredibly invasive and destructive to our city and I never want to see it happen again,” said Mayor Dan Gelber, who proposed the speed restrictions. “We are a barrier island with only a few arteries over the water, and when one is disrupted it’s an incredible hardship for our residents,” he added.

There are already slow speed zones in some areas around Miami Beach for a variety of reasons, including to protect manatees and prevent accidents, but the new restrictions would uniformly apply to the areas around bridges, said Aleksandr Boksner, Miami Beach’s chief deputy city attorney. Violators would get a civil citation from Miami Beach police officers.

Adrian Ramirez, a supervisor at the Jet Ski rental company American Water Sports South Beach, said that he didn’t object to 300-foot slow speed zones near bridges, but thought it would be difficult for the city to get all water sport enthusiasts to comply.

“I could see the safety aspect of it,” Ramirez said. “Maybe they’ll learn, but maybe the city will just hand out a hell of a lot of tickets before everyone catches on.”

Ramirez agreed that the restrictions would prevent saltwater from coating the undersides of bridges in areas with low clearance because personal watercraft don’t shoot water up as high when they’re moving slowly.

Motorboats and personal watercraft aren’t the only factors that can cause saltwater corrosion. Any action that sprays saltwater onto the underside of a bridge, including a storm, can contribute to the problem.

But storms are short-term events, whereas motor-operated water vessels repeatedly pass under bridges, explained Dave Beck, a structural engineer who has worked in marine environments.

“A hurricane or a storm is a limited event and it’s at intervals,” Beck said. In an area like the one around the MacArthur, he added, “you have a consistent issue of boats and jet skis having a lot of activity under the causeway.”