Construction Halt of Three Highways Using DR Girder Launching Method
On the 25th, construction was halted on three highways nationwide using the same method due to a collapse incident at the Cheongnyongcheon Bridge, which is the 9th construction section of the Cheonan-Anseong section of the Seoul-Sejong Expressway.
The Ministry of Land, Infrastructure, and Transport plans to decide whether to resume construction after thoroughly verifying the safety of the construction method.
Background of the Collapse Incident and Work Suspension
The DR girder launching construction method was applied at the Cheongnyongcheon Bridge where the recent incident occurred. This method involves pre-manufacturing the deck and beams to connect the piers and assembling them on-site. It is a technology that uses launching equipment to push the girder into place, reducing the construction period and increasing efficiency.
However, opinions have been raised on the need to reevaluate the safety of this method following the incident. Consequently, the Ministry of Land, Infrastructure, and Transport has temporarily suspended construction on projects such as the Sejong-Anseong Osong Line Bridge, Daesan-Dangjin Daehogji Bridge, and Hamyang-Hapcheon Hagamcheon Bridge. Investigations are also underway on sections of national roads where the same method was applied. Voices calling for thorough reviews to ensure safe bridge construction are growing louder.
Analysis of the Cause of the Incident
The DR girder launching method involves installing girders produced in the factory onto the piers using a special piece of equipment called a launcher. The recent incident occurred during the process where the launcher was removing itself after placing the girder onto the pier. It has been confirmed that the girder shifted to one side, resulting in a cascade collapse.
Police have captured evidence that the girder was not properly secured on the pier and are closely investigating compliance with construction procedures and safety regulations. They are collecting relevant materials and conducting on-site inspections to identify the exact cause of the incident.
In the future, there will be an increasing necessity to strengthen safety inspections during the construction process, as well as to improve operational manuals for launching equipment. These measures are expected to contribute to preventing similar incidents in the future.
What is the DR Girder Launching Construction Method?
The DR Girder (Deck-Rib Girder) launching construction method is a method of constructing bridges by pushing out the DR girder with launcher equipment. This method is primarily used for bridge construction that crosses rivers, valleys, and existing roads. This approach allows for efficient and safe bridge construction.
1. What is DR Girder?
Precast concrete girders are manufactured as an integrated unit of deck and rib.
This structure does not require additional slab casting on-site,
and it has high rigidity and excellent constructability.
2. Features of the Launching Construction Method
This method does not require cranes, allowing girders to be pushed out and installed from one side of the pier.
This approach entails pre-manufacturing in a factory and assembling on-site, shortening the construction period compared to conventional girder methods.
Additionally, it is applicable even in cases where there are obstacles below the bridge, making it suitable for crossing valleys, railways, and roads.
Advantages and Limitations of the DR Girder Launching Construction Method
| Category | Advantages | Limitations |
| Construction Period Reduction | Pre-manufacturing reduces on-site processes | Need for safety of the launcher equipment during construction |
| Improved Safety | Possible in areas where crane access is difficult | Risk of deformation and accidents during girder launching |
| Cost-Effectiveness | Minimizes the need for crane installation and large equipment | Potential for major accidents if equipment malfunctions |
| Environmental Protection | Minimizes direct construction over roads and rivers | Additional equipment checks needed when using a launcher |
Conclusion and Outlook
The DR girder launching construction method has been evaluated as highly efficient; however, the recent incident has raised the necessity for a review of its technical safety.
In light of this event, the Ministry of Land, Infrastructure, and Transport will conduct a thorough investigation to inspect construction sites currently under the same method. If necessary, they plan to establish technical improvement measures and enhance safety management plans.
In particular, ensuring the fixation and stability of the girders during the operation of launcher equipment has emerged as a key task. It is expected that there will be a strengthening of detailed inspections of machinery and improvements in construction procedures moving forward.
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