ABSTRACT
Since this century, the sanitation program for the Medellin River and its tributary streams is being developed. The North Interceptor Project is framed within the treatment system and corresponds to underground transportation of wastewater. The tunnel alignment passed through alluvial and anthropogenic deposits, in which boulders dispersed randomly in the ground were difficult to anticipate. Boulders present a significant and potentially costly challenge when mining small (less than 3 m) diameter tunnels. During the construction stage, the TBMs were stuck several times due to metric boulders at the excavation face. As the TBM specifications did not consider this event, relief shafts were required to remove the obstruction and repair or remove the TBM. In this paper, a sequential game is proposed to be used as a new approach of risk assessment in order to have a clear picture between expected outcomes and cooperative strategies. The expected outcome of this game reveals that cooperative strategies may provide the highest payoff for each player.
