A Sustainable Decision-Making Framework to Evaluate Land and Seaside Disposal Options for Tunnel Spoil: A Case Study of Trabzon

Abstract

Sustainable urbanization is essential for developing cities. To ensure the success of planned construction projects, designers must prioritize sustainability by lowering emissions and reducing costs. Tunnel projects are common worldwide, but disposing of the excavated material presents a significant challenge due to unsuitable geographic conditions. While coastal cities with mountainous terrains have historically used spoil for sea filling, this study offers alternative landside options to promote sustainability. By using a conventional analytical hierarchy process (AHP) method for multi-criteria decision-making (MCDM), the study evaluates land use, sustainability, slope, and drainage lines as constraints for the AHP method. The transportation-related greenhouse gas (GHG) emissions are also considered to reduce environmental damage. Particle swarm optimization is used to determine the minimum transportation distance from the excavation zone to the dumpsite. As a sub-criteria of land use, the seaside is also considered a dumpsite compared with other options on the land side. The spatial analysis results of the case study show that suitable landside sites are available for the Trabzon tunneling project. Although coastal areas in Trabzon have been used for spoil dumping for filling purposes in the past, landside deposition is a viable alternative. The suitability ranks of land and coastal filling options are relatively similar, and selecting the seaside as the dumpsite for the Trabzon tunneling project reduces CO2 emissions. By adopting sustainable practices, we can realize a better future for our cities and the environment.