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A Strategy for Ground Space Enhancement through Underground Roads: A Focus on the Naebu Expressway and the Bukbu Expressway in Seoul

Seung-Hyun MinㆍSanghyun HongㆍDarae JungㆍYoungbeom Kim

The Naebu Expressway and the Bukbu Expressway were established in the late 1990s and are representative arterial roads in Gangbuk that connect the east and west of Seoul. They form a network that spans 7 autonomous districts and 14 administrative dongs in Gangbuk, existing as three-dimensional structures above the Jicheon Stream while traversing existing residential areas. Consequently, these two arterial roads are considered significant constraints on regional development and peripheral maintenance projects. Additionally, concerns have been consistently raised regarding the traffic flow and communication capabilities of the arterial roads, including the number and direction of access roads and access lamps, as well as arrangement and installation intervals. Therefore, the plan to underground the Naebu Expressway and the Bukbu Expressway is justified in promoting the project from the perspective of enhancing the overall urban spatial structure of Gangbuk and Seoul, particularly in terms of traffic management.
Following a traffic technology review, it has been determined that the Naebu Expressway and the Bukbu Expressway can be undergrounded while maintaining road linearity and traffic capacity similar to that of the present in all sections, with the exception of some tunnel sections. This plan outlines three strategic directions with the aim of converting ground roads into underground spaces and subsequently restoring people, life, and nature to the ground space that has remained underutilized thus far. The first strategy involves creating a pedestrian-oriented spatial structure by prioritizing people-centered spaces. The second strategy focuses on reconnecting disconnected spaces in areas where vitality has been lost, thereby promoting the revitalization of life and streets. The final strategy aims to reconnect and restore disconnected natural elements, transforming the space around the road into a nature-friendly environment that incorporates water, forests, and sky. o realize these objectives, a comprehensive review of the current status of the entire section was conducted, and plans were proposed for each type by categorizing the target sites into six types. Types 1 and 2 aim to strengthen and revitalize the function of central areas by creating people-centered spaces through the restoration of water spaces and the reintegration of the natural environment fragmented by arterial roads, while also addressing regional disconnection. Type 3 necessitates organizing the transportation system and implementing road diets for the lower general road alongside undergrounding. Type 4 involves rearranging the transportation system and implementing road diets for arterial roads, alongside plans to secure housing, expand maintenance projects, and introduce annual shopping malls to enhance residents' quality of life. Type 5 focuses on reorganizing the linkage system between arterial roads through underground means, potentially creating large-scale idle spaces that can be repurposed for necessary facilities. Lastly, Type 6 pertains to tunnel sections, where maintaining the current tunnel structure is inevitable, prompting a review of plans to utilize some spaces for various purposes while retaining the structural characteristics of the tunnel.
Since the plan to underground the Naebu Expressway and the Bukbu Expressway involves replacing the above-ground overpass, it is challenging to reduce costs associated with limited travel time, vehicle operation, and traffic accidents. However, considering the long-term perspective, the ripple effect and development potential of underground roads are expected to be significant if the method of calculating benefits is adjusted to account for the revitalization of the local economy, reduction of air pollution, and improvements in living conditions and the environment under the overpass. Additionally, institutional supplementation for private investment projects is necessary to facilitate the project. Support measures and institutional supplementation, such as subsidies for actively utilizing state land by identifying business sites open to private sector participation or easing long-term loan conditions, are required.
The plan to underground the Naebu Expressway and the Bukbu Expressway marks the beginning of balanced development in Gangbuk. Beyond restoring nature by reconnecting green areas and streams obscured and disconnected by facilities, it will be possible to restore urban functionality and vitality and achieve balanced development in Gangbuk in the long term by promoting spatial maintenance and development of the connected ground. Now is the time for active discussion and review of the Naebu Expressway and the Bukbu Expressway, which have been excluded from previous discussions.