China set a new world record on Tuesday by replacing a section of railway bridge in just four hours without interrupting the normal service of the railway, said China Railway Construction Corporation (CRCC).

The previous quickest record stood at about 12 hours, as the CRCC said "there is nothing like this in the world," adding that the process allowed bridge replacement work to be done during a window when the railway was not in use, said the CRCC. 

The unprecedented efficiency was accomplished using a smart machine that enabled major maintenance to be done quickly and safely. 

Named after the Taihang Mountains that separate northern and central China, the Taihang machine is a foldable device that can be transported by rail and "transformed" on site, Wu Jingpeng, a senior engineer in charge of the bridge replacement project at the China Railway Fifth Survey and Design Institute Group, told China Media Group (CMG).

The device, also the world's first railway bridge replacement machine, debuted to replace a worn-out bridge section on the Shuohuang railway line in north China's Hebei Province, according to the CRCC.

By the end of 2022, China's national railway operating mileage had reached 155,000 kilometers. The country's existing railway lines have been in operation for many years, with some dating back over a century, which surpass their lifespan of 50 years, and more than 40 percent of China's railway bridges have been in use for more than 30 years, according to the company.

Therefore, the need of maintaining efficiency and safety of such railways is urgent in China, as it is crucial to promptly maintain and repair them to minimize disruption and ensure smooth operations.

Quick process within four hours

The first step of bridge replacement carried out with Taihang involves the preparation of a new bridge section with ballast and rail tracks at a nearby station area, according to the CRCC. The new section is then loaded on to Taihang which transports it to the section that needs to be replaced.

The Taihang machine is then transformed to prepare for the replacement process which involves lifting the existing bridge section, loading it on to a vehicle and installing the new bridge section in its place.

During this process, the machine ensures precise positioning and adjustment of the new bridge section to ensure proper alignment and stability.

After the new bridge section is installed, Taihang quickly restores the railway line to operational status by compacting the track bed using large hammers.

Tech innovations, breakthroughs

The successful task of the Taihang machine symbolizes a significant technological advancement in China's railway infrastructure maintenance and commitments to innovation in the rail industry.

The device, equipped with cutting-edge technology and equipment such as precise positioning and adjustment mechanisms, handles different bridge replacement tasks in complex terrain and on high piers.

Wu told CMG that current railway bridge replacement methods used around the world were limited to specific situations, including platform lateral movement and gantry crane replacement.

"Existing replacement technologies all require long periods of line interruption and track changes during construction, which affects railway traffic organization and operational safety and cannot meet the requirements of bridge replacement tasks in special situations such as high piers, complex terrain, lack of construction platforms or work sites."

According to the CRCC, the speed of the replacement work can be allowing the bridge replacement work to be completed during a window when the railway is not in use, so as to avoid interruption to normal service and impact on train services. 

Using the high-tech Taihang machine, the CRCC achieved instant traffic after the bridge replacement, with the overall efficiency increased by about 2.5 times (as compared to the traditional construction method), and a greatly reduced replacement process and construction team, Wu told CMG.