AECOM Seating Bowl Generator

For every stadium and arena design, the center piece is the seating bowl design. The geometry of the seating bowl has the most significant saying of the layout of other program spaces. For seating bowl design, there is always one thing that takes the highest priority, and usually is the very starting point of bowl design process. It is called Sightline Design.

Modern sightline Design was first established by John Scott Russell in 1838, and the method has stayed almost the same for nearly two centuries. Basically, the process involves calculation of riser height for each row, given the known previous rows’ treads and risers. This calculation insures spectator’s sightline is not blocked by people sitting directly in front. Besides this calculation in bowl section, the whole process also includes a sightline check in the floor plan, which makes sure that sightline is not blocked by people on  both sides. The development of Seating Bowling Generator focuses on the section calculation part, because this is the part that can benefit most from automation.

There are existing digital tools for automating sightline design, but the deficiencies of each are prohibitive for serious application: the proprietary software made for theater and  music halls are not compatible with the specific needs of a sports venue, and the simple grasshopper/dynamo scripts are too simple to consider multiple design constrains, such as buildability and ADA.

Seating Bowl Generator started with the goal to address the deficiencies of these tools, while integrating itself into the BIM workflow.

This tool uses a customized Revit family as the main input UI. This decision addresses the challenge of balancing simplicity and flexibility: under various scenarios, each row needs to have the flexibility to override sightline rules and conform to other constrains, and one way to achieve this without an excessively complicated UI is to use Revit family’s parameters as input interface. Users will be able to make changes to each row by change parameters of that row, as well as graphically move, copy and delete rows.

This tool addresses the buildability constrains by several means. To control the number of different precast molds needed, there is a parameter for the amount of change in riser height from the previous row. To address floor-to-floor height constrain, the tool can fix a specific row to a certain level, as long as it has a bigger than minimum C-value, and remake the section.

To take the section into 3D geometry, this tool can either directly draw section profile for manual geometry building, or link sections to profile families that drives the bowl geometry.

This tool has been used in several AECOM projects, and has since proved its value. It is a great tool for design studies of both new and existing seating bowls, because it has the flexibility to take numerous constrains and considerations into account. It helps designers build confidence in their proposals by fast design iterations and 3D geometry generation.

Many thanks to AECOM’s sports venue experts: Vittorio Ansourian, Hal Johnson, Scott Sayers, and many others who provided valuable inputs on the course of making this tool.

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