Switch from Open-Cut to Tunneling Method Raises Construction Cost Outlook
Bidding Expected This Year, Construction to Start Next Year... Targeting Completion by 2030
The second phase, sections 7 and 10, of Gwangju Metropolitan Rapid Transit Line 2 is expected to be re-tendered within this year after five failed bidding attempts.
According to the Gwangju Urban Railway Construction Headquarters on October 6, the headquarters is pursuing design changes for sections 7 and 10 and is currently negotiating total project cost adjustments with related government ministries, including the Ministry of Economy and Finance and the Ministry of Land, Infrastructure and Transport.
Section 7 (from the back gate of Chonnam National University to Ochidong Overpass) and section 10 (from Bonchon-dong OB Beer Factory to Yangsan District Intersection), which are part of the second phase construction, have been considered challenging due to narrow road widths, heavy traffic, and the complexity of underground utilities such as water supply, sewage, and electrical facilities. Although five bidding attempts have been made so far, all failed because the estimated prices (15.16 billion won for section 7 and 11.4 billion won for section 10) were too low, leading construction companies to avoid participation.
In response, the headquarters has decided to switch from the existing 'shallow open-cut method' to the 'tunneling method,' initiating design changes and a reassessment of construction costs. The shallow open-cut method involves excavating the road surface, which is less expensive but causes significant inconvenience to citizens due to traffic control and prolonged construction periods. The tunneling method, on the other hand, involves deep underground excavation, which increases costs but offers the advantages of shorter construction periods and minimized road closures.
There are projections that construction costs may inevitably increase by around 50 billion won due to the design change. However, the headquarters stated, "The exact amount can only be determined once the final design plan is confirmed after the supplementary process is completed."
As of now, the sixth bidding announcement for sections 7 and 10 is expected within this year, with construction likely to begin next year. If construction commences as planned, the relatively shorter duration required for the tunneling method means that the overall schedule for the second phase (targeted for completion in 2030) should remain on track, according to the headquarters.
An official from the Gwangju Urban Railway Construction Headquarters stated, "Since design revisions and government consultations are still underway, we cannot confirm the specific re-tender schedule or the amount of cost increase yet," but added, "We expect to issue the bidding announcement within this year and select a contractor under improved conditions."
Meanwhile, as of August, the civil engineering progress rate for the second phase of Line 2 remains at 3.24 to 5.8 percent.
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