Dynamic Sign Guidance Optimization for Crowd Evacuation considering Flow Equilibrium

Minghua Li,Li Ma,Chengyong Xu,Yun Wei,Yan Xu,Xinqiang Chen

doi:10.1155/2022/2555350

Abstract

The dynamic exit sign has been verified as an effective means to guide the pedestrian during evacuation. The most critical mechanism with dynamic exit sign guidance is to balance the pedestrian flow on each exit route by optimizing the direction of signs. This paper formulates a bi-level programming model for the direction optimization problem of dynamic signs in buildings. In the bi-level program, the upper-level model is a system optimal model, aiming to minimize the total travel time by optimizing the dynamic sign direction. The lower-level model is a pedestrian assignment model satisfying the dynamic user optimal principle that describes the evacuee exit/route choice behaviour to achieve a balanced pedestrian distribution on the route. A method based on the fundamental diagram, the cell transmission model, and the point-queuing theory is developed to estimate evacuation travel time considering congestion and queuing. A heuristic algorithm is extended to solve the bi-level program. Finally, the proposed methodology is validated with numerical examples. Results reveal that the proposed model can produce the optimal dynamic sign direction, significantly improving the evacuation efficiency.

Highlights

Exit signs in buildings can help people find escape routes and emergency exits quickly, reducing evacuation time and the risk of casualties. erefore, exit signs are widely used in buildings, especially in large public places with complex layouts such as transportation hubs, stadiums, and theatres
Some of the existing studies related to exit sign direction use only path distance as route metric for direction optimization and ignore the crowd distribution, much less the flow equilibrium state [4, 6,7,8,9,10,11]. Another part of the research considered a balanced assignment of evacuation flow using metric that reflects the travel cost of the route, including route flow [12, 13], density [2], flow to capacity ration of route [4], and travel time [14]. en the exit sign direction is determined based on the optimal route in flow equilibrium state
We propose a method for calculating route travel time based on a cell transmission model. e method is able to calculate the delay time caused by congestion, which is considered by traditional methods, and the queuing waiting time, which is not considered by traditional methods

Summary

Introduction

Exit signs in buildings can help people find escape routes and emergency exits quickly, reducing evacuation time and the risk of casualties. erefore, exit signs are widely used in buildings, especially in large public places with complex layouts such as transportation hubs, stadiums, and theatres. Some of the existing studies related to exit sign direction use only path distance as route metric for direction optimization and ignore the crowd distribution, much less the flow equilibrium state [4, 6,7,8,9,10,11] Another part of the research considered a balanced assignment of evacuation flow using metric that reflects the travel cost of the route, including route flow [12, 13], density [2], flow to capacity ration of route [4], and travel time [14]. To the best of our knowledge, there are few studies that combine these two aspects For closing this gap, we will study both exit sign direction optimization and flow equilibrium assignment of the evacuation network from the perspectives of both evacuation managers and evacuees.

Related Work

Methodology

Algorithm

Findings

Numeral Experiments