Pedestrian Modelling for Resilient Structures
Designing resilient infrastructure is always a top-of-mind concern for engineers. With each project, we’re aiming to ensure the infrastructure asset can adapt to changing environments so that it continues to serve its function. As the effects of climate change become more severe and new threats like global pandemics change the way we use our structures, designing for resilience is only growing in importance.
While Entuitive uses a range of solutions to design resilient structures – from seismic and fire to our suite of sustainable performance service offerings – this article explores how pedestrian modelling can be used to create more resilient infrastructure. Specifically, it will focus on transit applications and stadia. These assets serve large volumes of people making the performance of these spaces even more important.Pedestrian modelling is a tool that allows us to model our spaces for a range of events and see how they perform for the users of those spaces. After viewing the models, we can layer in mitigation measures, be they operational changes or physical changes to the layout, to test the effectiveness of various strategies and their ability to enhance the resilience of the infrastructure.
These events can range in timescale, from short duration “shocks” that require an immediate response, to “prolonged stresses” that require a shift in how we use and interact with our built environment.
A shock is a short duration event that causes an abrupt disruption to an operation or an asset and requires a quick response. Examples of shock events that our infrastructure must respond to are emergency scenarios and high demand, special event type scenarios. While it is not uncommon to design infrastructure to provide code compliant life safety or to meet capacity requirements for a specific large event, considering these events on a spectrum and quantifying performance allows us to further enhance the resilience of the infrastructure.
When designing for life safety, we typically design our spaces following prescriptive travel distances, stair and exit widths, and types of signage to inform building occupants how to interact with this egress strategy. However, this fails to take into account the human factors of how actual building users interact with spaces. We know from the literature and our own observations that occupants exit a building the way they enter, even if this is not the shortest egress path when analyzing a floor plan. Pedestrian modelling, and evacuation modelling in particular, allow us to analyze our spaces to determine a range of expected egress times and determine if this performance is in fact adequate, or if revisions to the egress strategy are required. This is especially important in buildings with high occupant loads where queuing during evacuation is critical to understand.
Level of service requirements addressing the daily movements of users is a typical base case consideration for most infrastructure. An example of this criteria is in the design of transit infrastructure, where the reliability of movement is paramount to the success of the system. For transit stations public circulation areas and vertical circulation elements are sized to meet a pre-established level of service.
However, special events such as a nearby sporting event or gathering can dramatically increase the passenger demand at these stations. It can also change the overall passenger movement pattern and introduce large amounts of counterflow in a station that might normally see one-way flow depending on the time of day. This is becoming increasingly important as transit-oriented developments create transit that is more integrated with its surrounding urban context, and, by extension, more susceptible to a range of events that may not have been initially considered during design.
In such instances, pedestrian modelling allows the design team to assess the public circulations areas within the infrastructure for potential special event scenarios and to determine how best to accommodate them. Mitigation measures can be tested to determine their effectiveness, such as temporary changes to circulation paths in the station (i.e. dedicated one-way paths to eliminate counterflow) or operational changes to increase throughput and improve intuitive wayfinding for those who may be using the station for the first time. An example of opportunities to design resilient infrastructure and as discussed in a recent Ensight article on transit-oriented developments, is to identify event scenarios that create stresses on the infrastructure’s capacity and to build in amenities to accommodate these fluctuations in volumes and as was done at Victoria Station in Calgary, Alberta on Calgary Transit’s Red Line.
Unlike the sudden nature of shocks, stresses are prolonged events or trends that change the environment (natural or manmade) that an operation or asset is exposed to. This requires the infrastructure to adapt to the new environment to ensure it still functions and meets performance requirements.
A natural stress that is becoming increasingly important in most new and existing infrastructure is endemic or pandemic response and preparedness. COVID-19 fundamentally changed the way we interact with the built environment and altered our expectations of how spaces perform. These changes aren’t static – our interactions with, and responses to, the built environment continue to evolve as the virus evolves.
The pandemic taught us that our movement patterns and the density or queues that we anticipate are important for our perception of safety and comfort regardless of any current health guidelines. We now have the information needed to design and test our spaces to be better prepared for the next endemic or pandemic. We now know how we might reconfigure the layout or alter capacities to better maintain business continuity. We can also proactively test mitigation measures to determine their effectiveness.
Manmade stresses, like technological innovation, also force our infrastructure to adapt. Changes in mobility behaviours such as increased trends towards on-demand transit services, active modes and micro mobility, as well as technology changes such as how fare purchasing and gate processing occurs all have impacts on the throughput of users. These trends are producing new conditions that must be quantified and designed for. Similarly, event centres and stadiums are experiencing changes in the use of these spaces and new technology is being introduced such as security processing and ticket scanning which produce queues and must be accounted for in the layout of these public spaces. As technology continues to evolve, the impact of these systems on our infrastructure will continue to change and represents an opportunity to make use of space that was previously allotted to queues or for security processing.
Entuitive recently completed a project where entry vestibules were sized to accommodate current mag and bag security equipment, which consist of a walkthrough metal detector with adjacent bag searches. The relatively low throughput of this system dictated the vestibule size and the number of equipment lines needed to ensure the maximum expected queue time met the client goals. This is common for sport venues to allocate such large areas to security processing and ticket taking.
However, the same design was also assessed using contactless walkthrough security systems which have up to 10x the throughput. While not formally allowed by some professional sports leagues, understanding how this future technology impacts the layout and performance of the space allowed the design team to proactively design for this future scenario and determine the best way to make use of the reclaimed space for revenue generating functions, such as more concessions or retail.
This same project also leveraged pedestrian modelling to test concourse layouts and ensure the placement of washrooms and concessions was optimized for a range of event types and capacities. This allows the concession throughput to be improved with a direct benefit to revenue.
Infrastructure, be it new or existing, must appropriately adapt to a range of shocks and stresses to ensure that it can provide the required performance. Pedestrian modelling has been shown to be a design tool that can enable this resilience by quantifying how the infrastructure may respond to these events and the effectiveness of certain mitigation strategies. Specific benefits include:
- In the case of sports venues and event centres, testing a range of scenarios and ensuring that concourses and vestibules are appropriately sized to provide the desired fan experience while also improving revenue opportunities. This contributes to world class facilities that can attract world class events.
- In the case of transit infrastructure, testing mitigation measures to be prepared for the next pandemic. This provides the reliability expected by transit operators and their customers that the service is safe, comfortable, and adaptable.
- From a Transit Oriented Development perspective, ensuring integrated infrastructure that responds to the innovative mobility trends and that are adaptable to the unique demands of these urban environments. This ensures the transit-oriented community is positioned for growth, development, and vibrancy long into the future. This supports sustainability.
If you’d like to learn more about our pedestrian modelling or fire engineering services, reach out to Matthew Smith, Associate, Fire & Structural here.
 SFPE Guide to Human Behavior in Fire