NTSB says bridge over-rotation the cause of 2020 towboat accident

The National Transportation Safety Board (NTSB) has said that the probable cause of the contact of the tow of the Trent Joseph with the Barataria Bridge on November 22nd 2020 was a corner of the bridge’s swing span protruding outside of its protective fendering into the navigable channel. This was subsequent to recently attempted repairs to the limit switch system that controlled the swing span’s rotation limit.

Towing vessels Trent Josephand George C were towing two barges southbound in the Barataria Waterway on the date of the incident. While passing through the open Barataria Bridge, the second barge contacted the bridge’s swing span. The bridge, which was the only means of road access for the community of Barataria, was damaged and remained unusable until November 28th. There were no injuries and no pollution reported. Damage to the barge was negligible, while damage to the bridge was reported to be more than $500,000.

The 67ft-long Trent Joseph was towing two barges behind in a single string by means of a tow bridle and shock line extending an estimated 70 to 75 feet from the towboat’s stern to the forward barge. That barge, the KS 4513, measured 140ft long and 45ft wide, and had on its deck a cargo of concrete fish boxes for an artificial reef project.

The aft barge, JMSS Mobile, measured 264ft long and 51ft wide and carried an excavator crane and associated equipment. There was no deck cargo or equipment overhanging past the hull of either barge. The captain of the Trent Joseph stated that he wanted to place the larger and wider JMSS Mobile at the head of the tow with the narrower KS 4513 aft, but, because the head of the JMSS Mobile did not have any deck fittings to which the crew could secure the towing bridle, they had to place it at the back of the tow with its stern coupled to the stern of the KS 4513 and its rake facing aft.

Behind the barges, connected by an estimated 10ft to 15ft tow line, was the George C, with a crew of four, operating as the tail boat. As the tail boat, the George C would act based on the instructions given by the operator of the lead boat to use its propulsion to keep the barges from running over the lead boat if it were to slow down or stop. As described by its captain, the George C acted as “the brakes” for the tow. Additionally, according to the captain of the Trent Joseph, the tail boat could also act to help move the tow to port and starboard as needed.

While passing through the open Barataria Bridge, the second barge contacted the bridge’s swing span.

Both the Barataria Bridge’s centre and east fenders had red navigation lights to mark the ends and middle of each fender. The east fender’s red lights were removed for repair before the accident. The captain of the Trent Joseph stated that, as the tow approached the bridge, the two red lights marking the centre fender should have been visible to him, but were not.

The Captain used a spotlight to look for the fenders when approaching the bridge. When the Trent Joseph was about 100ft from the bridge, the captain saw with the spotlight that the swing span had “over-rotated” and extended past the centre fender wall.

Louisiana Department of Transportation and Development maintenance records indicated that two days before the accident work had been conducted on the bridge’s limit switches. Those switches prevent the movement of the swing span beyond a predetermined point.

The NTSB also noted that the bridge’s entire fender system contained previous damage and said that it was structurally unsuitable for protecting the bridge as designed. he report also notes that According to USCG records, from 2001 to  November 22nd 2020 there had been nine incident investigations related to vessel contacts with the fendering system of the bridge.