We employ a simulation-optimization approach to coordinate large pedestrian streams in Mecca, safely.
Our objective was challenging: to plan crowd movements in one of the largest and most difficult to control mega-events on the planet. Set in a desert environment hostile to human life, the Hajj attracts millions of faithful who attempt to perform the religious rituals once in their lifetime. We began by digitizing the local pedestrian infrastructure such as roads, walkways, stairs, escalators, tunnels, camps, street blocks, and sanitary facilities. Based on this digital infrastructure we developed a pre -event simulation of how the crowd flows through the infrastructure and finally designed a mathematical planning model and algorithm to determine safe pilgrim group departure times and routes for the stoning-of-the-devil ritual (Rhamy-Al-Jamarat). Year for year, we were guests in Saudi-Arabia and gained a deeper understanding of the Hajj organizational structure. With growing experience, we refined our model-based planning and improved our understanding of how to structure and process the massive amount of input-data. We contributed to the Hajj planning process by providing a solid planning method aimed at optimizing safety through spatio-temporal coordination of pilgrim flows.