Description
Coupled CFD-Evacuation models have been slowly developing as technology and research into human behaviour has progressed. Programmes such as Thunderhead’s Pathfinder or FDS Evac have shown great potential to demonstrate how we can use digital tools to model health and behaviour of humans in fire scenarios. However, how can we use these insights to optimise the holistic design of underground stations, drive more sustainable, integrated design of tunnel ventilation systems (TVS) and challenge the status quo of pre-defined evacuation times?
For the past several decades, the ventilation system design of underground spaces like tunnels and metro/subway stations have progressed independently of the architectural design of the egress routes e.g. stairs, escalators, emergency staircases, etc. Both specialist teams work to deliver the same aim from different perspectives – the safe evacuation of passengers to a place of safety without exposure to fire smoke. Both teams use advanced simulation software, yet they hardly interact. Could they not deliver a better optimised design, if they benefited from each other’s work?
This paper sets out to address this question. Through an approach that couples CFD output to agent movement in pedestrian models, the study discusses the collaborative steps necessary to understand and design for efficient passenger egress in a sustainable manner. The involvement of Fire Engineers, Transport Planners, Architects and Tunnel Ventilation Engineers under a single digital design philosophy and modelling strategy is crucial in iterating towards a safe, well-rounded design with a minimum carbon footprint.
To demonstrate the benefit of this “total architecture” approach, the paper focusses on a case study that was delivered to a subway client in the USA. A proprietary coupled CFD-pedestrian model analysis was carried out to assess passenger evacuation routes and speeds in response to soot visibility, temperature and asphyxiant exposure. The findings suggested that through better passive smoke management, passengers could be kept safer for longer and only need to evacuate through one station entrance; an outcome that deleted an entire station entrance from the baseline design, with significant carbon and cost savings for the client.
