||Urban development and the need for new facilities have led to an increase in the use of urban utilities. These various utilities are generally located under the public highway. Therefore, underground space is limited by the width of the public highway. Because of the increase in urban utilities, the need for maintenance of these utilities and the lack of space, the underground is now very often saturated. Sometimes, the situation is so inextricable and so anarchic that the implementation of a new urban network becomes hardly possible. In addition, trench digging due to work on existing networks or on the addition of a new network generates much traffic interruption. To solve this problem, an urban utilities tunnel can be used. In this case, all the urban utilities are located in a single tunnel. Thus, saturation of the underground space decreases, there are fewer errors in the zone plan used, maintenance is easier, there is no traffic interruption and it is possible to add a new urban network without disrupting the public highway. However, the urban utilities tunnel is expensive compared to classical solutions. Because decision-makers only work based on economic criteria, this solution is rarely chosen. Therefore, to promote the urban utilities tunnel in France, a national research project was created. One of its goals is to develop a multicriteria method integrating the following criteria: safety, sustainable development, economy, maintenance, risk analysis, development facilities
Moreover, the sewer network seems to induce most of the constraints. Thus, another goal is to study the influence of the drainage network location (inside or outside the tunnel) on the general cost of the urban utilities tunnel. This paper details both problems.