An LLM-powered Agent Framework for Heterogeneous Evacuation Behavior Modeling under a Moving Threat in a Public Plaza
Organizations: School of Transportation and Logistics, Southwest Jiaotong University, Chengdu, 610031, China · Fujian Police College, Fuzhou, 350007, China
Abstract
Modeling heterogeneous evacuation behavior under a moving threat is difficult because human perception, memory, and evidence evaluation are not well captured by fixed rules. We propose a novel LLM-powered agent-based framework to represent these internal decision processes. Each pedestrian agent perceives a private symbolic ASCII view, maintains a Memory-based Knowledge Graph derived solely from individual observations, and makes decisions through persona-conditioned prompts under a common sampling configuration. A compressed decision context with stateless memory preserves trial-and-error experience across turns while excluding reasoning traces, and a validation engine separates behavioral choice from physical feasibility by executing routes only over observed terrain. We evaluated eight personality compositions in eight paired randomized blocks within a simulated public plaza. Usable-exit knowledge was strongly associated with evacuation success: 89.5% of agents possessing such knowledge evacuated, compared with 1.05% of those without it. Personality compositions also differed in their evaluation of remembered threat evidence: the proportion of danger assessments varied by 0.265, while high-urgency, low-directness decisions ranged from 11.41% to 34.33%. After direct threat sightings, responses converged, with 99.6% of assessments classifying the situation as dangerous. Movement was selected in 99.8% of decisions. Overall, evacuation outcomes were strongly associated with information access, while evacuation time was jointly associated with spatial geometry, information, and affect. The framework provides an auditable approach to generating endogenous behavioral heterogeneity through persona-conditioned LLM agents in crowd-evacuation simulations.
Figures & tables
| Archetype | O | C | E | A | N |
| Average | 50 | 50 | 50 | 50 | 50 |
| Calm-independent | 50 | 55 | 40 | 45 | 30 |
| Rule-following | 40 | 70 | 45 | 60 | 50 |
| Anxious-conformist | 40 | 45 | 62 | 60 | 72 |
| Bold-solitary | 68 | 35 | 35 | 40 | 32 |
| Block | Content |
| Identity | An ordinary pedestrian acting on local perception, its own known map, memory, affect, and messages received |
| Map | The fixed north-up orientation, the @ -relative offset convention, and the glyph table of Table 3 |
| Judgment | Target choice belongs to the agent, route legality to the engine; the evidence clause; the default target-distance band |
| Intent | intent and urgency as a standing goal that persists until the agent changes it |
| Route options | Fields of the engine-computed routes (length, familiarity, crowding, clearance from A or D , reach) and the rule that the shortest route need not be chosen |
| Past experience | Use of the decision-context capsule and of the engine’s feedback on the previous response |
| Symbol | Meaning |
| ? | Outside the perception map or occluded |
| . | Walkable ground |
| # | Wall or outside the building |
| T | Tree or fixed obstacle |
| E | Exit |
| G | Gate, open |
| Measure | Definition |
| Evacuation | |
| Evacuation time | Turns from run start to reaching an opening |
| Trajectory length | Distance walked along the executed trajectory |
| Evacuation efficiency | Shortest exit distance over walked distance, capped at 1; zero when unresolved |
| Critical safety margin | Smallest distance to the adversary over the run |
| Mean threat distance | Mean distance to the adversary over the run |
| Stage | Memory excerpt (translated) | Interpretation | Decision or plan |
| Case 1: From uncertain signals to escape and exit search | |||
| 1. Situation unclear | “I wanted to stop and observe to clarify the situation, without hastily following the others.” | The meaning of others’ behavior is still unclear. | The stated plan is to observe before deciding whether to follow others. |
| 2. Threat confirmed | “The 2 shouts I heard earlier … were probably warnings.” “Escaping comes first; exploration can wait.” | Earlier sounds are now interpreted as warnings. | The decision changes from continuing activity to moving away from the threat. |
| 3. Another exit needed | “Next, I need to find an exit that is still open or a direction with more people, and keep moving away from the northeast.” | Escape remains necessary, but the known gate may be unusable. | The next decision maintains threat avoidance and includes looking for other exits. |
| Case 2: From choosing a known exit to checking and abandoning it | |||
| 1. Known exit chosen | “I remembered that [the gate] was to the south, so I decided to go south, away from the armed person and toward the known exit.” | The known exit provides a destination for escape. | The selected goal is to reach the known exit. |