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As the world races to address the challenges of COVID-19 , the need to re-examine how people travel has never been more important.
Not only do we need to continue to design safe, sustainable, energy-efficient, cost-efficient buildings and infrastructure, but now we must also factor in the important added criteria: ensure recommended physical distancing between pedestrians in shared spaces.
“The virus isn’t simply a health crisis; it is also a design problem.”
Kim Tingley, The New York Times, How Architecture Could Help Us Adapt to the Pandemic
To this end, we’ve been working diligently to find ways that Autodesk software can best be used as people return to shared spaces such as offices, campuses, retail, sporting events, religious institutions, parks, streets, parking lots, public events, transit stations and ports.
Adding on to this body of work, in this article we’ll examine in more detail how to use Mobility Simulation for Autodesk® InfraWorks® to conduct pedestrian mobility simulations that factor in current global design challenges presented by COVID-19.
For more on using Autodesk products to support getting back to work, check out how we’re helping AEC professionals return to and reimagine the built environment.
WHAT IS MOBILITY SIMULATION?
Simply put, mobility simulation is the study of interactions between humans and infrastructure along any route.
To this day, private car travel is the dominant mode of transportation in many cities. However, as populations increase and car ownership increases, there is an inevitable (and often rapid) corresponding increase in traffic congestion. Historically, the solution has been to just build new roads and highways to accommodate more vehicles, but the space to build new roads in already congested areas becomes increasingly limited over time, forcing transportation engineers to find new solutions.
In the current era, there’s a growing need for holistic design of transportation systems that factor in end-to-end person-trip planning through numerous modes of transportation and environments, and tools that can accommodate this. Urban mobility, pedestrian mobility, and cyclist mobility are increasingly important parts of the picture.
For most cases, the desired result of a mobility simulation is to minimize the amount of time required for a person to safely travel from point A to point B (and from Point B to Point C, etc.), whether they’re on foot, cycling, using a scooter, travelling in a vehicle, using mass transit, or a combination of these options.
Depending on the number of modes of transportation, the amount of travelers, and the amount of stops in the journey, simulating mobility for different design proposals can be a simple task (such as simulating pedestrians travelling through indoor or outdoor spaces), or an extremely complex one (such as simulating the impacts of multiple modes of transportation and many travelers with numerous stops in a complicated transportation system that factors in variables such as signage, transit stations, and traffic control devices).
The benefits of minimizing the resources and time required to transport people from Point A to Point B, then Point B to Point C, and so on, are immense. Money can be saved, pollution can be reduced, material resources can be conserved, and human interactions in shared spaces can be improved.
WHAT IS MOBILITY SIMULATION FOR AUTODESK® INFRAWORKS®?
Mobility Simulation for Autodesk® InfraWorks® is an integrated multi-modal mobility simulation engine, capable of simulating the impacts of your InfraWorks design proposals on all modes of transit (except air and water transportation).
When you use InfraWorks’ multi-modal Mobility Simulation engine to create animated simulations of transit, parking, personal, and/or taxi-mode modeling, you’ll be able to review key performance indicators such as Person-Hours Travelled, Person-KM Travelled, multi-modal level of service calculations, as well as economic and environmental assessments that are available as Excel and PDF reports.
Notably, you can also use this tool to simulate pedestrian mobility in outdoor spaces such as pedestrian crossings, or even in indoor spaces, such as a large retail space (think Costco, or equivalent), an airport terminal, or a shared office space.
And, while mobility simulation is a highly-specialized domain when designing for vehicles and multi-modal traffic, Mobility Simulation for Autodesk® InfraWorks® makes designing for pedestrian mobility a much simpler task without a prerequisite need for users to have an extensive background in transportation engineering.
In fact, once you’ve learned the basics of simulating pedestrian mobility with Autodesk InfraWorks, it’s simple enough to then refocus your simulation goals to factor in the impacts of COVID-19.
HOW DO I USE MOBILITY SIMULATION FOR AUTODESK® INFRAWORKS®?
At a high level, Mobility Simulation for InfraWorks is a straightforward process:
1. Create or open an InfraWorks model and navigate to the area of study.
2. Create or define a Traffic Study Area in-canvas.
3. Click Analyze > Transportation > Mobility Simulation.
(Mobility Simulation opens in a separate application window).
4. Define mobility parameters, then generate results and animations in the InfraWorks Mobility Simulation application window.
For help with general usage of Mobility Simulation for InfraWorks, see To simulate mobility in the InfraWorks online help.
HOW DO I USE INFRAWORKS TO SIMULATE PEDESTRIAN MOBILITY FOR PHYSICAL DISTANCING CONSTRAINTS?
For this example, I’ll walk through the steps required to perform a basic mobility simulation that accounts for physical distancing constraints between pedestrians in an indoor space.
But before we get started, it’s important to get a sense of five critical design considerations for simulating pedestrian mobility in shared spaces under physical distancing constraints:
- Follow recommended physical distancing guidelines
Ensure that pedestrians are able to adhere to minimum safety guidelines for physical distance on their routes, whether they’re travelling to work on mass transit, going to school, walking through a supermarket or retailer, travelling through an airport, etc. The accuracy of your mobility simulation will only be as good as the model you build, and to what extent it takes into account numerous variables such as airflow and space capacities– so the more precise the infrastructure and building data you can use in your mobility simulation, the better. - Reduce two-way pedestrian traffic
Avoid bi-directional pedestrian traffic at all times, especially in crowded indoor spaces such as walkways. Enforce one-way traffic wherever possible. - Increase availability of serviceable walkways
Always verify the level of serviceable walkways (acceptable levels are Levels of Service A through C, D or beyond results in a failed travel network) at all times during your simulation period. - Compute optimal number of people-groups for the route
Ensure that groups of people do not exceed the safe capacity of the route, and stops along the route. - Compute optimal release frequencies for groups of people
Ensure that groups of people are appropriately staggering route start and end times where relevant so that overlap between groups that exceeds safety limits do not occur. Based on the structure of the travel network, your simulation, and proposed release times, you can create and evaluate the best (safest) proposal. Consider the use of alternative doors wherever possible to add entrance/exit points for additional streams of unidirectional traffic.
SAMPLE USE CASE: PEDESTRIAN MOBILITY SIMULATION IN SHARED INDOOR SPACES (+PHYSICAL DISTANCING)
As a best practice, you should approach indoor pedestrian mobility simulation in InfraWorks one architectural floor of the desired structure at a time.
Consider the following scenario:
How might we simulate pedestrian mobility for the three-story shared office space pictured below as a Revit model?
Here’s another look at the same building in Revit with the hidden elements disabled from view:
For the sake of simplicity (not to mention performance), it would be best to approach this scenario with a separate mobility simulation for each floor of the building. This could be handled by three designers working in parallel, or one designer working through each simulation in sequence.
Additionally, as another best practice, we will be modeling the mobility simulation parameters in 2D for the majority of our work time, to keep things simple. Only when the mobility simulation is properly configured and running as expected will we add in the 3D building model from Revit to convey more accurate realism and context of the site and surrounding infrastructure.
So, instead of using the 3D models pictured above, we’ll instead just use the 2D plan view of the first floor of this building to get our mobility simulation started.
Tip: This is great news for everyone that doesn’t have an already existing Revit model of their desired building to use in a mobility simulation, because something as simple as a 2D floor plan is more than enough to conduct an effective mobility simulation.
In this example, I am literally taking a screenshot of the Entry Level Floor Plan view in Revit to use in Mobility Simulation for InfraWorks.
Here’s the screenshot I’m using as the entry level floor plan for a three-story office building, saved as a raster image (.bmp):
Tip: To improve resolution of your screenshots, save them to .bmp format then add them to the Raster Manager available with AutoCAD and related products such as Autodesk Civil 3D. This can help to improve display resolution when you add raster imagery to Mobility Simulation.
Next, let’s open up Autodesk InfraWorks, and identify our study area. This is where the Model Builder for Autodesk InfraWorks becomes your best friend — within a few clicks you can automatically build a full model of up to 200 sq. km. for an area you specify. See To create a model with Model Builder for help with creating your first InfraWorks model.
Using the Model Builder, we’ve created a model of the geographic location and surrounding infrastructure for the office space we’re assessing for mobility. You can see the result below: an InfraWorks model containing the building we want to assess for indoor pedestrian mobility.
Just to give you a better sense of the context, here you can see the Revit model when imported into InfraWorks at the building’s real-world geographic coordinates. In this example, terrain from Revit is also included in the 3D model import, and displayed in InfraWork. This can be done to provide better perspective to the designers and stakeholders, but isn’t required to complete a mobility simulation.
We can also display just the floor plan in the model instead as a starting point. This can be done using any supported raster or vector as a 2D terrain overlay in InfraWorks. In the image below, you can see the 2D terrain overlay in InfraWorks created from the screenshot of the Revit model entry level floor plan.
Now that we have a building floor plan and an InfraWorks model, we can define a traffic study area and open the Mobility Simulation application window.
In the InfraWorks model, click Analyze > Transportation > Mobility Simulation.
Single-click in-canvas to draw individual points for your traffic study area boundary, then double-click to finish the last point.
Note: When prompted to convert planning roads to component roads, click No. (For multi-modal mobility simulation with vehicles, you would often click Yes here, but for the sake of this simulation, this step is unnecessary and could slow performance).
Right-click on the traffic study area you created and click Mobility Simulation. Note: You can ignore the warning (shown below) about missing intersections and click OK. For the purposes of our sample use case, intersections are not necessary.
So here we are: we’ve got the InfraWorks model created, the traffic study area created, and the model data open in the Mobility Simulation application window.
Let’s employ a few tricks here to get started quickly.
Click File > New, then click Cancel. (Yes, Cancel it immediately. This will eliminate a good portion of project setup for our use case).
Now that we’ve canceled the New Commuter Model – Parameters Wizard dialog, we can start configuring our simulation with less data noise to begin with. Here’s what that looks like:
Now, click Display > Content, and select the Images tab of the Content dialog.
Click the Add a new local Image to this network ONLY button.
When prompted in the Select Image File dialog, select the raster image file representing your floor plan and click Open. You can accept the default Import 2D Pictures settings by clicking OK.
Click Apply, then click OK
Do not be alarmed at this point when the image does not appear on screen yet.
The image, although loaded, will still not appear on the screen. In order to visualize the image permanently, right-click anywhere on the screen. Select Display > New Image at Cursor. (Hint: the “cursor” in Mobility Simulation for InfraWorks is shown in the image below, it’s always located at the origin point between the X and Y axes)
Specify a name for the image and select the floor plan that you just added to the Content section in previous steps, then click OK.
The floor plan image is placed in the model.
Now, click the Layer tab in the right sidebar of the Mobility Simulation application window. You’ll notice that the first Layer/Aspect is selected in the top row of the table, and the name of the Layer/Aspect is displayed above it.
Enable “Handle – End” and “Handle – Other”. You can do this by check-marking corresponding cells in the first layer column so that they have a white color fill, not black.
Click the top of the view cube in the mobility simulation modeling space so that you are looking down at the floor plan from a birds-eye view, or plan view perspective
Now, let’s start using the selection handles we just added to this simulation layer. This can be a bit trick if you don’t know the nuance here: use the middle button on your mouse (not the left or right button) to click and drag. This middle button click-and-drag operation is how all object selection is performed in mobility simulation.
Click and hold the middle mouse button while dragging to create a rectangle at top right corner of the image. You can see the selection box that is created in Mobility Sim as a red rectangle.
Once you’ve selected the upper right corner of the floor plan, release the middle mouse button. You will see your selection handles appear for the object and control point.
Right-click and select Adjust.
Input the dimensions corresponding to this real-world office space. You can do this in the Adjust dialog under the Length and Width columns (X=Length, Y=Width).
To find these dimensions, I revisited the Revit model for this office space floor plan and found that my building dimensions are roughly 80 meters wide and 64 meters long. Click Apply, then OK when you have input the dimensions. Do not close the Adjust dialog yet.
Next, scroll to the right in the Adjust dialog and checkmark the Fixed column for this row, then click Apply, OK, then Close.
The image is now scaled and fixed properly. Press Esc. on your keyboard to de-select the image if it is currently selected
Use the scroll bar on your mouse to zoom in and verify that the dimensions are accurate.
Now we are ready to start placing mobility elements in our transportation network, such as destination areas and walkway
Let’s start by evaluating how employees might show up for work and enter the main entrance on the west side of the building, starting from the parking lot, and continuing into the building until they reach their desks.
To do this, we will create an area representing the parking lot in front of the office building, which is the entrance point for employees leaving their cars and beginning to walk towards the office building.
Right-click, and select Area > New Area at Cursor. (Hint: the area will be placed at the location of the cursor, at a size that is relative to your zoom level in the model. For geometric accuracy, zoom in when creating the area. You may need to try this a few times to find the right sizing for your purposes).
For example, in the image below, we’ve moved the image with a simple right-click and drag operation, then zoomed-in so the cursor is located in the main parking lot outside the front entrance of the building.
Once the area is placed, you’ll notice that every vertex and the origin hold an origin icon and four arrows. The geometry of each vertex and arrow can be modified separately when selected individually using the middle mouse cursor selection method.
Next, let’s place another area in the model, representing a destination for employees who enter the building (most likely this would be their desks or office rooms).
For the sake of simplicity, let’s assume that 25 employees will be arriving at this building between 8:00 am and 9:00 am, they will park in the front parking lot, and will proceed along one route to the same large shared office room (like a large open-office or cubicle room).
What we can do here is copy-paste the first area that we just created to represent the parking lot, then move it to a different location in the building and modify the shape to fit the desired room. Middle mouse click-and-drag to draw a selection box over the corner of the area.
With the area now selected, right-click, select Edit > Copy.
Now, right-click and select Edit > Paste. The new area will be pasted on top of the existing one, and will be selected.
You can click and drag the selected copy of the area using your left mouse button. In the image below, you can see we have placed this second area at the location of a large corner office space.
Next, all we need to do is use the middle mouse button to select the right side of the area and re-size it to more accurately fit the office space. The image below shows how to use the selection box to do this. Once you’ve selected the appropriate vertices/lines in the area, use the left mouse button to click-and-drag for re-sizing.
This is what we’re looking for (shown in the image below). This second area that we’ve added to our mobility simulation model represents the destination for employees along the simulation route that we are currently creating.
Now that we have an entrance area and destination area in place in our model, let’s create our walkways. For the sake of simplicity in this demonstration, we’ll just create a single walkway.
To start creating a walkway, rotate the model so that the entrance area faces due west (the mobility simulation engine inserts walkways along the Y axis in your model by default, so this is just a quicker way to get started).
Now, right-click and select Walkway > New Walkway at Cursor.
At this point, to compensate for physical distancing, modify the default 2 meter width in the New Walkway dialog to a width that can only accommodate a single pedestrian on a one-way path.
0.6 meters width works for this use case.
Now, select the walkway and drag it into place. The walkway must be located inside the entrance area and then follow a path inside the main entrance.
We will continue to add walkways to finalize the path that our pedestrians will take on their journey into the building.
Important: At this point, we also need to enable “Walk Centrelines” in the Layer tab of the sidebar (this will enable grips for modifying the start/end stations of walkways instead of moving the entire walkway at once).
In the image below you can see we’ve created a path from the parking lot, through the main entrance, through some interior doors in the entryway, then a right-turn down a corridor followed by another right-turn into the room with the employees’ desks.
Now we will join the walkways into a continuous path. This can be done by selecting two adjacent walkways at a time, then right-clicking and choosing Walkway > New Connection.
Here’s what that looks like close-up:
Here you can see the full path from entrance to end destination when zoomed-out:
Important: it is critical that you click File > Save at this point. The walkways will not be attached to the areas unless you save the model.
At this point, we’re nearly ready to start our simulation. We just need to do a little bit more work to configure the demand on this transportation network. For starters, let’s hide the visibility of the floor plan raster image temporarily so we can focus on the simulation parameters.
To hide the image, un-checkmark “Images” in the Layer sidebar.
Select the Simulation tab in the sidebar and click New Simulation.
Input a name for your simulation.
Select the simulation you just created and click the Activate Simulation icon.
Now let’s configure demand and demand division. Click Demand > Demand Divisions > New.
For this simple demonstration use case, we will keep demand at 100, meaning that 100% of people will use this path to travel (as compared to simulations with multiple points of entrance/egress). Click Apply, then OK.
Next, click Demand > Demands. In the Directed Demand: Origin-Destination Matrices tab, click Add.
Input a new name for this Demand setup, then click OK.
Now, we will configure the amount of people travelling from area 1 (the parking lot) to area 2 (the office room that employees go to to start their day at their desks). Input the desired number of people that will travel along this path in row “1”, column “2” of the table. For this example, we will input 25 to represent 25 people.
When ready, click OK. We’re now at the final few steps!
Click Display > Content, and navigate to the Pedestrians tab in the Content dialog.
Click the plus icon in the left corner. The Add Shapes from Database dialog appears. Click to select (or use Shift or Ctrl keys to multi-select) the 3D models of people that you want to use in the simulation (you can also import your own), then press OK.
Click Apply, then OK.
We are now ready to play our mobility simulation! Click the play button in the simulation tab to animate pedestrian mobility along the route you have defined. You can also re-enable the display of your floor plan to add some more detail to your simulation by check-marking Images in the View tab of the sidebar.
From here, there are any number of permutations of mobility simulation parameters you can define. To finish the pedestrian mobility simulation for this office, we would create an additional two simulation models, for the 2nd and 3rd floors of the building.
Additionally, we’d also likely create more walkways and segment demand divisions to ensure that only uni-directional walkways are available in the model, and to factor in the reality that not everyone works in just one room of this building, nor always uses the main entrance door.
And that’s it for now folks! This should be a nice starting point for you to dip your toes into Mobility Simulation for Autodesk® InfraWorks® while planning for current global design criteria.
Let us know how it goes!
For more on using Autodesk products to support getting back to work, check out how we’re helping AEC professionals return to and reimagine the built environment.
This article was written by Elliott Rosenfeld, Senior Content Experience Designer at Autodesk, in close collaboration with Edmundo Herrera, M.S., P.E., Transportation Engineer and subject matter expert at Autodesk. This engaging and informative blog post would not have been possible without Edmundo’s expert help.