In a freak accident, a crane boom on a cargo ship entering the Port of Houston on the Thursday before Christmas damaged two beams and punched a 10- by 15-ft. (3 by 4.5 m) hole in the deck of the Loop 610 bridge.
Three northbound lanes of traffic remain closed as the Texas Department of Transportation (TxDOT) engineers access the damage and develop a plan to repair the 135-ft. (40.5 m) high bridge. “We’re in no hurry to do repairs; we want to do it right,” said Norm Wigington, spokesperson for TxDOT. Wigington explained that the bridge sustained severe damage to one horizontal support beam and moderate damage to a second beam. Also, the bridge armature popped up in the middle of the deck when the Bahamian-flagged cargo ship, the Rickmers Tianjin, hit the bridge at its highest point.
Since the accident occurred at 9:30 in the evening, bridge traffic was not extremely heavy; however, three people in vehicles were slightly injured in collisions when the bridge deck seemingly “exploded” in front of them. No one aboard the 574-ft. (172.2 m), 23,239-ton (21,126 t) ship was injured.
When the accident happened, a lot of debris from the bridge fell into the water, said Rosie Barrera, Port of Houston spokesperson. The ship channel was closed while an Army Corps of Engineers crew was brought in to survey the bottom of the channel to make sure falling concrete had not blocked the shipping lane. Corps area engineer Mike McClenan said that soundings showed that the debris did not project into the navigable area of the channel and posed no risks for shipping. “We needed at least 36 ft. (10.8 m) of draft under the bridge and our survey showed 37.5 ft. (11.25 m),” McClenan said.
Another concern was stabilizing the bridge and removing hanging cables so no additional debris would threaten ships passing underneath. All northbound bridge traffic was diverted for a day while this work took place.
This is not the first time that a ship’s crane has struck the bottom of this bridge, which is about 60 ft. (18 m) lower than two other major bridges over other parts of the 53-mi. (84.8 km) long channel. According to Lt. Gregory DeLong, spokesperson for the Coast Guard Marine Safety Office for Houston/Galveston, the bridge has been struck by ships’ booms about four times in the last 10 years, doing only minor damage each time. This accident, however, is much more significant and qualifies as a “major marine casualty, which means damages of $500,000 or more,” DeLong said. Initial estimates for the repairs are $1 million and may be higher when the contract is awarded later this month. State officials hope to recoup the costs of the repairs from the ship’s owner, Double C Shipping Company Ltd., based in Greece.
The Rickmers Tianjin was carrying steel products and hazardous materials, said Lt. Ken Bryan, senior investigative officer for the Coast Guard Marine Safety Office. Bryan said his office will be examining previous cases to determine if crane accidents such as this one may be part of a causal trend that requires additional regulations or procedures. “We’re conducting a thorough investigation and all parties are being cooperative; we’ve interviewed all crew members,” Bryan said.
The question of how such an accident could occur and even the particulars of how it did occur are still under investigation, DeLong said. The Coast Guard’s official investigation will take several months as findings are processed through local, district and national offices. “Unofficially, we know the crane caused the accident,” DeLong said.
Although the Rickmers Tianjin was in the Coast Guard’s vessel traffic system, the controllers don’t issue specific movement orders to the ship captains as air-traffic controllers do for airline pilots. All vessels coming into the Houston Ship Channel, one of the longest and busiest in the nation, must take on board a local pilot, who has both a U.S. Coast Guard-issued license, as well as a State of Texas Pilot Commission. When a ship will be entering or leaving the channel, the shipping agent for that company “orders a pilot,” said T.J. Nelson of the Houston Pilots Association.
For incoming ships, the pilot boards at the Sea Buoy, about 9 mi. (14.4 km) off Galveston, and stays with the vessel until it is docked. The pilot advises the master of the ship regarding special features of the ship channel, but the ship’s captain is held accountable for an incident. When the ship must pass under a bridge — and the majority of the Houston cargo docks are upriver of the Ship Channel bridge — the pilot and the master calculate the “ship air draft,” the amount of space between the waterline and the uppermost point of the vessel. The space between the waterline and the bottom of the ship channel bridge is 135 to 138 ft. (40.5 to 41.4 m) depending on the tide. The weight of the ship’s cargo also may affect clearance.
Cargo ships are all outfitted with one to several cranes of various configurations, said Officer K.M. Stillwell of the Port of Houston Police Department. Stillwell said that the Rickmers Tianjin’s five cranes were a bit unusual, an older style that is seldom seen on ships that visit the port.
Accidents of various kinds are not uncommon in the ship channel. Port records show that last year, of the 229,102 vessels that transited the waterway, 200 were involved in incidents, which could be everything from a sinking barge to a vessel losing control of its steering. Sixteen of those accidents involved big ships hitting either another vessel or a stationary object, such as a dock. The most recent incident of a ship hitting the underside of the channel bridge was two years ago, according to DeLong.
To decrease opportunities for accidents along the channel, which is bordered by chemical and petroleum plants and flows over thousands of pipelines, a four-year dredging and widening project is half completed. The channel is being deepened from 40 to 45 ft. (12 to 13.5 m) and widened from 400 to 530 ft. (120 to 159 m) along its 53-mi. (84.8 km) length. This wider waterway will do away with the need for the navigational ploy that pilots have dubbed “Texas Chicken.” Houston pilots know that two large tankers can pass each other in the close quarters of the channel if the oncoming ships aim directly toward each other, then suddenly veer to one site. The water “cushion” that results allows the ships to slide safely past each other.
Nevertheless, the Rickmers Tianjin accident was one of the more unusual occurrences in this busy port, but it only halted shipping for a few hours. Commuters on the Loop 610 bridge will continue to be inconvenienced by traffic congestion until the bridge repairs are done, perhaps by the end of February. The Coast Guard’s investigative findings are months away and may or may not show a trend of similar accidents. In the meantime, it seems certain that Houston pilots and ship masters entering the channel will carefully calculate their ship’s air draft and will lower their booms.
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