# Evacuation Model

Evacuation models are simulation tools designed to predict the movement and behaviour of individuals during an emergency evacuation.

## Simulation Scale

Small-scale models, typically used for building evacuations, focus on individual or group dynamics within confined environments, such as offices, residential buildings, or public spaces, taking into account factors like building layout, fire spread, and occupant behaviour. These models often incorporate agent-based or microscopic approaches to simulate detailed human interactions and decision-making processes. One of the last surveys shows that there are 72 small-scale evacuation models currently in use for fire evacuation.
In contrast, large-scale evacuation models deal with mass evacuations from broader areas, such as urban environments or regions affected by natural disasters like wildfires or earthquakes. These models, often macroscopic or mesoscopic, emphasise traffic flow, route optimisation, and infrastructure capacity, addressing the logistical challenges of moving large populations over significant distances.

## Simulation Resolution

The simulation resolution in evacuation models refers to the level of detail and granularity used to represent evacuees and their environment during a simulation.
At the microscopic scale, each individual is modelled as an independent agent with unique characteristics such as speed, decision-making abilities, and interactions with others, making this approach ideal for detailed simulations of small spaces like buildings.
Macroscopic models, on the other hand, treat people as a collective flow, using principles similar to fluid dynamics to represent large crowds or populations in more general terms, often applied to large-scale evacuations such as citywide scenarios.
Mesoscopic models bridge the gap between these two. This approach represents groups of individuals as a collective unit while maintaining some individual behaviours, making them useful for medium-sized environments or scenarios where detailed interaction is less important than overall flow.
The choice of simulation scale is crucial in balancing model complexity, computational cost, and the specific goals of the evacuation study.

## Movement Representation

Movement representation refers to how the physical movement of evacuees is simulated within a space, influencing the accuracy and realism of the model.
Grid-based models divide the environment into discrete cells, with individuals moving from one cell to another based on simple rules, often used in cellular automata approaches. These models are effective for simulating movement in structured environments like corridors but can be limited in capturing fluid, natural movement.
Continuous models provide a more flexible representation, allowing evacuees to move freely in any direction within a continuous space. These models are often used with agent-based or force-based simulations, where individuals adjust their speed and direction based on personal preferences, obstacles, and interactions with others.
Network-based models abstract the environment into nodes and links, where movement is simplified to navigating from one point to another along predefined paths, commonly used in large-scale scenarios like transportation networks.
Each method of movement representation has strengths and is chosen based on the environment's complexity, required realism, and computational efficiency.