Case Studies

SEAPILE dolphins help keep this bridge pier protection system in service

The Ladies’ Island Bridge, in Beaufort, South Carolina, crosses the Intercoastal Waterway at Route 21. Northbound vessel traffic approaching this bridge on the Intercoastal Waterway must make a sharp turn to starboard, followed by a hard turn to port just after the bridge. These maneuvers are frequently complicated by tidal crosscurrents, combined with an incoming flow from the mouth of a nearby creek.

As a result of these conditions, vessels can lose steerage and collide with the bridge pier protection system. In the past, certain portions of the bridge pier protection system have required frequent replacement, sometimes even while being repaired from earlier impacts.

Bends and currents in the Intercoastal Waterway make for difficult navigation at Ladies’ Island Bridge

In 1998, marine contractor T.I C., of Savannah, Georgia, under contract with the South Carolina Department of Transportation, replaced existing timber pile dolphins at the ends of the bridge pier protection system with two SEAPILE composite marine piling dolphin clusters. Each cluster of piles was constructed using 13-inch (330mm) diameter SEAPILE pilings, only thirteen of which were required to achieve the same energy absorption as the 19-pile timber cluster that was replaced.

According to Larry Wadman, T.I.C.’s installation superintendent, except for the removal of old wooden timber piling from the bottom of the waterway, the pile driving went very smoothly and there were no installation problems related to the use of composite piles.

A marina operator located immediately across the Intercoastal Waterway from the Ladies’ Island Bridge has observed frequent collisions between barges and ships and the SEAPILE dolphins - impacts that would have destroyed timber dolphins. “The SEAPILE installation looks the same as it did on the day it was put in,” he observes. Curtis Brice, district bridge maintenance supervisor of the South Carolina Department of Transportation, says, “The dolphins using the SEAPILE piling have performed beyond our expectations. We will definitely look at using more of these composite materials to help protect our bridges in South Carolina.”