After the sudden incident on the Lixinsha Bridge in Guangzhou, a reporter from CNR (China National Radio) reviewed publicly available media reports and found that in recent years, water traffic incidents have occurred frequently, especially ship-bridge collisions. According to incomplete statistics, at least 19 ship-bridge collisions occurred within four years. These 19 incidents not only caused casualties but also led to severe damage to bridge structures, and even complete collapse.

　　Among these 19 incidents, 3 caused casualties. For example, at 22:21 on January 10, 2022, the vessel "Qiji 622," owned by Zhongshan Shipping Freight Co., Ltd., departed from the Huangqi Beicun Port Terminal loaded with 72 tons of bulk cargo bound for Hong Kong. While passing the Fenggang Bridge over the Shuikou Waterway, it struck the 9th span (navigation span) of the right carriageway of the Fenggang Bridge, causing the second-level wheelhouse at the bow to collapse. The engineer was crushed and injured by the collapsed steel frame and subsequently died after treatment proved ineffective.

　　In terms of economic losses, on August 19, 2020, Typhoon Higos made landfall directly at Jinwan, Zhuhai. Affected by the typhoon, a Changzhou-registered crane vessel anchored for shelter in the waters near the Tiansheng River mouth of the Modaomen Waterway had its mooring lines break, drifted with a dragged anchor, and its crane housing struck the Modaomen Bridge upstream. The incident caused no casualties or water pollution, and the preliminary estimate of direct economic losses totaled approximately 8.5 million yuan. As early as October 15, 2015, a sand-dredging vessel striking and damaging the Zhaoqing Xijiang Bridge (a combined road-rail bridge) attracted great attention from all sectors of society. The incident suspended railway operations for 55 hours, with economic losses as high as 40 million yuan, and had a considerable social impact.

　　Why have ship-bridge collisions occurred repeatedly in recent years? Fan Wei, deputy director of the Hunan Provincial Key Laboratory of Wind Engineering and Bridge Engineering and deputy director of the Department of Bridge Engineering at Hunan University, said in an interview with a CNR reporter that, on the one hand, with China's rapid development, waterborne and land transportation have also developed rapidly, with waterborne traffic volume growing by more than 10% for many years, and vessels becoming larger, faster, and denser. At the same time, China has built an increasing number of bridges over wide waters, with the total number of bridges exceeding 1 million, creating a pattern of many bridges and dense vessel traffic, so the conflict between the two has become increasingly prominent. On the other hand, vessels have poor maneuverability and long braking distances, and the accident rate is high under the combination of multiple factors such as weather and hydrology, which is also key to the frequent occurrence of ship-bridge collisions.

　　According to a report by China Water Transport, according to incomplete statistics, by the end of 2019, China had about 2,523 bridges of various types crossing high-grade inland waterway channels. Among them, there were 2,115 highway bridges, 210 railway bridges, 64 urban bridges, and 134 other bridges (such as pipelines). With the rapid growth of the domestic national economy, the inland waterway shipping industry has flourished, and inland waterway shipping traffic has become very busy. However, the navigable clearance height of waterway bridges is limited, or vessel pilots are careless and overconfident, or weather and hydrological factors have an impact, so ship-bridge collision accidents occur frequently.

　　Investigation: Human factors account for more than 50% of accidents

　　A CNR reporter reviewed the 19 ship-bridge collision incidents and found that the causes included a lack of or errors in crew members' ship-handling skills, and vessels drifting with dragged anchors.

　　Fan Wei's investigation found that human factors accounted for 54.3% of accidents, among which vessel overheight collisions caused by negligent lookout accounted for 42.1% of human factors. Accidents caused by anchor dragging and drifting accounted for 34.3%, and more than 70% of anchor dragging and drifting were triggered by typhoons, rainstorms, and rising tides. It can thus be seen that impacts caused by human factors and vessel anchor dragging and drifting are the issues most in need of attention.

　　For example, at about 1:08 a.m. on January 18, 2021, due to the excessive height of the vessel, the Lianxi Bridge in Lianzhou Town, Doumen District, Zhuhai City, Guangdong Province, was struck from upstream by a large cargo ship, causing the bridge deck to shift by about 10 centimeters and slightly injuring one crew member. On May 4, 2022, a cargo ship sailed from the Ertang Operation Area to the Tiandong Xiangzhou Operation Area. While passing the Napo Bridge in Tianyang District, Baise, Guangxi, due to improper operation, the bow of the cargo ship collided head-on with Pier No. 2 of the Napo Bridge. The pier surface was damaged, and the three people on the cargo ship were uninjured and all safely reached shore.

　　In terms of vessels drifting with dragged anchors, the main causes are typhoons, rainstorms, and rising tides. On August 12, 2020, a flood peak passed through Leshan, Sichuan. The flood peak from the upper reaches of the three rivers passed through the urban section of Leshan, Sichuan, and a sand and gravel transport vessel collided with the city-side of the temporary construction bridge for the Zhijiang Road Bridge under construction, causing the vessel to capsize, and part of the middle of the temporary bridge was destroyed by the collision. On August 19, 2020, Typhoon Higos made landfall directly at Jinwan, Zhuhai. Affected by the typhoon, a Changzhou-registered crane vessel anchored for shelter in the waters near the Tiansheng River mouth of the Modaomen Waterway had its mooring lines break, drifted with a dragged anchor, and its crane housing struck the Modaomen Bridge upstream.

　　A person in charge of a certain waterway affairs center said in an interview with a CNR reporter that common factors involving changes in the navigation environment include, due to constraints such as road alignment and land acquisition, poor site selection for river-crossing bridges, the angle between the bridge axis and the flow direction failing to meet regulatory requirements, insufficient curvature and turning radius of the waterway in the bridge area, rapid currents in the river section, turbulence caused by piers, and poor visibility, all of which can easily lead to ship-bridge collision incidents. The incident on April 15, 2015, in which a vessel struck the Xi'anting Bridge over the Ganzhu Creek Waterway, belongs to this category. The three-vessel collision on February 13, 2017, in the waters of the Shakou Bridge on the Xiaolan Waterway, apart from the pilot's factors, was importantly caused by poor visibility on the curved waterway; fortunately, no damage was caused to the bridge.

　　The person in charge stated that navigational aid factors are one of the causes of accidents. These mainly include bridge-area marker placement, bridge-area waterborne navigational marks, and special marks in waters near the bridge area. Imperfect navigational aids in the bridge area, abnormal operation of navigational marks, poor visibility, and interference from surrounding lights are also among the important factors leading to ship-bridge collisions.

　　A relevant maritime official said in a media interview that "there are many bridges in navigable waters, the construction standards of old bridges are low, vessels are increasingly large, and the increase in the number of vessels has made the navigation environment complex and changeable. Poor management by shipping companies, weak safety awareness among vessel pilots, and a lack of ship-handling skills are also important reasons for the frequent occurrence of ship-bridge collision accidents."

　　Fan Wei said that in China, with the rapid development of three-dimensional transportation, the pattern of many bridges and dense vessel traffic has gradually taken shape, the ship-bridge conflict has become increasingly prominent, and ship-bridge collision accidents have occurred frequently, attracting great attention from departments such as China's Ministry of Transport. To this end, in 2020, China's Ministry of Transport and other departments issued a special document requiring: carrying out a special campaign to address ship collision hazards for bridges in navigable waters.

　　Experts: Physical energy-dissipation protective measures and early-warning protective measures should be strengthened

　　Ship-bridge collision accidents continue, not only causing damage to ships or bridges, but even leading to severe damage to bridge structures and even complete collapse, causing huge economic losses, casualties, and negative social impacts.

　　How should effective measures be taken? A person in charge of the aforementioned waterway affairs center said that shipowners and pilots should enhance their sense of responsibility. Subjective errors by vessel pilots are the most important cause of ship-bridge collision incidents, so it is very important to strengthen skills training for pilots and enhance their sense of responsibility and risk awareness. In particular, shipowners must have risk-prevention awareness and urge and strengthen business training for vessel pilots, crew members, and sailors. Second, pilots must strictly abide by navigation rules, concentrate their attention, make predictions when passing under bridges, and compare the dimensions of the vessel and the bridge to prevent bridge collision accidents caused by the vessel being too large.

　　In addition, waterway management departments should improve navigation conditions as much as possible. According to the requirements of the Waterway Law, waterway management departments have the responsibility to ensure unobstructed waterways and navigation safety. On the one hand, waterway management departments should improve waterway navigation conditions through waterway construction projects to meet the needs of the development of larger vessels; on the other hand, they should strengthen waterway maintenance to ensure the integrity of navigational aids and the normal performance of their functions. Waterway management departments should also keep pace with the times by adopting new materials, new technologies, and new methods, developing electronic navigation charts, formulating optimal route selection mechanisms for vessels, and promptly and accurately transmitting bridge-related information (such as real-time clearance height data of bridges ahead) to vessel pilots so that they can make timely judgments and responses. Waterway management departments should do more work in providing waterway information and provide fuller and higher-quality services for vessel navigation.

　　Regarding bridge anti-collision measures and design, Fan Wei believes that roughly three aspects can be considered. The first is optimizing the bridge span configuration and avoiding ship collision risks by changing the span layout. For example, an old bridge in Switzerland collapsed due to a ship collision. When the bridge was rebuilt, a cable-stayed bridge with a single span across the river was adopted, thereby eliminating the ship collision risk. This method is generally only applicable to newly built or rebuilt bridges, and its practical application is also constrained by factors such as the economic feasibility of bridge construction. The second is physical energy-dissipation protective measures, which dissipate ship collision energy through various forms of energy-dissipating devices or structures, often called passive anti-collision measures. "Physical energy-dissipation protective measures are like a vehicle's bumper, dissipating collision energy through the deformation of the protective measures and then protecting the bridge or the ship," Fan Wei said. The third is early-warning management protective measures, mainly using early-warning systems formed by optoelectronic devices to forecast and warn of potential collision risks, or other management measures such as navigation restrictions set by water transport departments.

　　Fan Wei said that, specifically, early-warning protective measures can be defined as a system in which multiple types of sensors, such as radar, cameras, and LiDAR, are deployed within a specific anti-collision protection zone to obtain the vessel's position, speed, and other key data in real time. These data are processed and analyzed in real time through data communication and processing units to build a spatiotemporal information model of the bridge area, providing a comprehensive view of the vessel's travel posture. Through multi-source data fusion, information provided by different sensors, such as AIS, radar, and video, is integrated to form more comprehensive vessel status and behavior information. Such measures are generally only applicable under the premise that both the vessel's power and the operator are normal, and are mainly used to reduce bridge collision accidents caused by human factors. It is difficult to completely avoid the risk of ship-bridge collisions, so they generally need to be used in combination with other measures. Compared with other measures, at present, buffer-type physical energy-dissipation protective measures (referred to as buffer energy-dissipation measures) and early-warning protective measures are the main ones. In practical application, the former is currently dominant, while the latter is also gradually attracting attention and being applied by the engineering community.

　　Fan Wei said that to reasonably apply various anti-collision devices to ship-bridge collision protection, a reasonable regulatory system needs to be established. Up to now, there are no detailed design specifications at home or abroad for bridge anti-collision devices and measures. Only by establishing a regulatory system can designers be effectively ensured to design various devices well in actual projects. Formulating reasonable design specifications requires the joint efforts of academia and the engineering community. (Reporter Li Hongpeng)