27 November 2025
On a construction site, it is not uncommon for two teams to need to occupy the same space at once. These occupancy conflicts, which are difficult to anticipate, often lead to delays and cost overruns. In fact, the tools most commonly used today for project planning, such as Gantt charts, do not allow for easy visualization of this type of issue. And as the number of activities increases, the complexity of interactions makes these charts difficult to interpret and update.
This is the focus of Stéphane Morin Pépin, professor in the Department of Construction Engineering at ÉTS. A specialist in construction project planning and management, he is rethinking the way schedules are designed and used. How can planning be made more visual, more realistic, and, above all, more useful for entrepreneurs in the field?
Beyond the Gantt Chart: Space-Time Planning
One central theme of Stéphane Morin Pépin's work is space-time planning, an approach that emerged in the 1990s. Unlike the Gantt chart, which breaks down a project into a series of activities, this method considers the spatial organization of the construction site. Based on the construction plans, the project is divided into sectors, each corresponding to an area of intervention.
Work teams, materials, and equipment are then distributed across space and time. This approach provides a dynamic representation that simultaneously visualizes spatial dimensions of activities (where they occur) and temporal dimensions (when they take place). It is no longer just a matter of coordinating tasks, but also of coordinating work teams operating in specific sectors.
During his PhD studies, Stéphane Morin Pépin carried the concept a step further by integrating the notion of occupied space, or occupancy rate, into his method. Each work team requires a specific space for its activities, which has a direct impact on site configuration, work sequence, and, consequently, work planning. By combining this area with those occupied by materials and equipment, it becomes possible to calculate the occupancy rate of a sector at a given time. Known as Dynamic Model of the Occupancy Rate Scheduling (DMORS), this model allows project managers to visualize and verify the compatibility of spatial resources and effectively prevent occupancy conflicts. They can then use this occupancy rate to optimize the work schedule.
From Theory to Practical Tools for Entrepreneurs
Stéphane Morin Pépin's current research focuses on transforming DMORS into an operational tool for project managers. The idea is to define, step by step, the procedures that will enable an entrepreneur to move from plans and estimates to a complete schedule based on DMORS concepts.
First, the method involves defining all the sectors that will be available throughout the project, then planning their succession and availability. This allows the contractor to know when each sector will be ready to welcome new teams, and then calculate the dynamic occupancy rate. This methodological framework will make it possible to establish schedules based on this rate, extract the information required for daily planning, and improve coordination between the various stakeholders.
Beyond planning, the schedule also becomes a source of strategic information: a basis that allows project managers to extract project cash flows, monitor work progress, and justify contractual deadlines in the event of a dispute. One challenge is to integrate this method with legal and administrative requirements based on traditional Gantt charts.
A Research Program Rooted in Real-World Needs
As part of his research program, Stéphane Morin Pépin has three main objectives. First, he aims to determine the required data to create and update a schedule based on dynamic occupancy modeling. Second, he seeks to better understand how this approach can facilitate the management of unforeseen events, comparing it to traditional planning methods. Finally, he explores the links between space-time planning and financial management in order to produce more reliable cash flow forecasts.
This work draws on the latest technologies—Building Information Modeling (BIM), Construction 4.0, and artificial intelligence—to design interactive interfaces and decision-support algorithms capable of assisting contractors in the day-to-day management of their construction sites.
Practical Benefits for Industry
This research offers many potential benefits. From a scientific perspective, it contributes to the advancement of knowledge in project management, dynamic modeling, and spatial planning. From a practical standpoint, it provides a methodological framework and concrete tools for reducing risks, avoiding usage conflicts, and improving productivity on construction sites.
Ultimately, this type of space-time planning could become a new standard in the construction industry, modernizing practices and strengthening collaboration between contractors, engineers, and architects.
For Stéphane Morin Pépin, the goal is clear: “I want my research to serve first and foremost those who are building, and to be useful in the field, daily.”
