Chinese researchers have conducted simulations indicating that major suspension bridges—key components of national infrastructure—are highly vulnerable to attacks by small drones carrying explosives. The study, published in the Journal of Railway Science and Engineering, found that a precision strike by a drone carrying as little as 30 kilograms of TNT could trigger the collapse of a suspension bridge if detonated near the cable anchorage point where the main suspension cables connect to support towers.

The research was carried out by teams from Southwest Jiaotong University and the China Railway Major Bridge Reconnaissance & Design Institute Company. Their model focused on a suspension bridge design similar to the Dimuhe River Bridge in Guizhou province, which has a main span of 538 meters and serves as a benchmark in Chinese engineering studies. Suspension bridges feature road decks supported by large main cables hung between towers, anchored firmly at both ends.

This work was motivated by the evolving nature of warfare, particularly the shift from large-scale firepower to precise, targeted strikes using unmanned aerial vehicles (UAVs). The ongoing conflict between Russia and Ukraine provided a real-world context, as Ukrainian forces have targeted key Russian logistical bridges—including the Antonovsky Bridge over the Dnieper River and the Crimean Bridge—with drone and missile attacks. These incidents underscored the susceptibility of bridges to relatively small and concentrated explosive assaults.

Using computer simulations, the researchers evaluated the impact of blast charges up to 50 kilograms of TNT detonated within 20 centimeters of critical structural points. The models revealed that an explosion near the main cable anchorage could cause a chain reaction, snapping cables and destabilizing the deck, ultimately leading to structural collapse. Even smaller charges—30 to 40 kilograms—detonated at close range posed a significant risk, and a 5-kilogram blast could sever cables if it exploded upon direct contact with the tower junction.

The study emphasized that the most vulnerable sections are the cable anchorage zones where the suspension cables meet the towers, highlighting the need for defensive measures focused on these points rather than simply increasing overall blast resistance. According to the authors, protection strategies should prioritize mitigating the risk of precise, close-range attacks rather than focusing solely on the magnitude of explosive force.

As China hosts the largest number of suspension bridges worldwide—including over 11,000 classified as “super-large”—these findings carry substantial implications for national infrastructure security and defense planning. The researchers called for further systematic examination of the damage mechanisms in these critical structures to better prepare against emerging threats posed by UAV-delivered explosives.