Evaluating the economic and social benefits of multiutility tunnels with an agent-based simulation approach

Purpose: Multiutility tunnel (MUT) has been recognised as a more sustainable method to place underground utilities than the traditional directly buried (DB) method. However, the implementation of MUT is hindered because of high initial construction costs and the difficulty to demonstrate its benefits, especially social benefits that are hard to be quantified. To address the limitation, this paper aims to quantify and compare both economic costs and traveller loss (i.e. an important part of social costs) of the MUT and DB method. Design/methodology/approach: An agent-based model (ABM) is developed, which considers attributes and actions of vehicles, interactions between vehicles and interactions between vehicles and the road network. The ABM is used to estimate traveller loss by comparing traveller time when the MUT and DB method is adopted, respectively. The traveller loss is combined with economic costs to estimate and compare the LCC of the MUT and DB method. To verify the ABM-based approach, it is implemented in an MUT project in Shanghai, China. Findings: Results of the study indicate: (1) When the DB method is adopted, periodic E&Rs cause severe traffic congestion and substantial traveller loss. (2) When traveller loss is not included in the LCC estimation, the DB method has a lower LCC in most scenarios. (3) When traveller loss is included, the relative LCC of MUT and the time it takes to cover the LCC of the MUT and DB method is largely reduced. Thus, when social costs are considered, MUT will bring more benefits than the DB method. Originality/value: Previous studies on comparing the MUT and DB method focus on investigating economic costs, while other costs, e.g. social costs, are not well addressed quantitatively. Besides, current studies of traveller loss estimation lack consideration of factors such as unique attributes, actions and interactions of vehicles and the network. Hence, this paper applies an ABM-based approach to involve these factors and produce more reliable estimation of traveller loss than existing approaches. Moreover, by integrating traveller loss into LCC analysis, this paper helps to understand the benefits of MUT thus assisting decision-making in selecting utilities placement methods.