Integrating 4D modeling and discrete event simulation for phasing evaluation of elevated urban highway reconstruction projects

Elevated urban highway reconstruction projects have complex geometry and limited space available, which may lead to spatiotemporal clashes. In addition, maintaining an acceptable flow of traffic without compromising safety in highway construction zones is another major issue for planners. This paper proposes a new method for generating and assessing reconstruction phasing plans and calculating the probability of stochastic spatiotemporal clashes associated with the optimal feasible phasing plan. A phasing plan assessment approach using a constraint-based system and 4D modeling is presented to define the feasible sequences in which the segments can be constructed or demolished. The result of this step is an optimal feasible phasing plan that meets a set of predefined constraints and creates no spatiotemporal clashes. This plan is then examined to calculate the probability of potential stochastic spatiotemporal clashes, which may happen when the variability of construction and demolition durations is considered, and to recommend the starting date of operations to minimize the probability of these clashes. The feasibility of the proposed method is explored through a case study.