A Convention Center Built for Acrobatics

Designing an all-in-one hotel, convention center, and transit building for use in worldbuilding.

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Preface

Years ago, I had a dream about a character with flight powers being chased through the big pyramidal atrium of a convention center.

I no longer remember exactly how that dream ended.

Since then, I’ve composed a short story based upon the dream. It’s embellished with concepts and worldbuilding that I’m pretty sure were not part of the original dream. Some of the embellishments are almost certainly a case of writing for an audience.

The story contains some action sequences that I worry would be hard for the reader to follow, if they don’t have an accurate mental model of the space in which the story is taking place. I will try to provide a written description in the story, but it might disrupt the flow of the story if I write as full a description as might be necessary. I want to illustrate this story to make it easier for the reader to visualize.

Illustrating this story is tricky, because dream architecture doesn’t pay attention to things like angles or perspective or questions of how tall an atrium needs to be to have the right angles for the illustration.

Therefore, I set forth to create an art reference for the story.

A textual description of the convention center

The setting is a convention center, externally pyramidal in form, with a pyramidal atrium in the middle.

The atrium is floored by a train station, with three platforms providing access to two pairs of tracks. These tracks have platform doors, which at their upper end meet with a mezzanine level running above the tracks. The mezzanine level provides the ticketing hall for the train station, as well as the walkways between the three platforms. The mezzanine level is shaped like an octothorpe (#), with two lines covering the tracks and two lines crossing them. These four crossing bridges are the upper level of the station. These bridges also support the “floor” of the atrium, which is a food court dining area. The hollows of the # are open to the platforms below, and the solids are covered in tables and chairs and planters.

The food court floor is surrounded by the base of the pyramid. It is these four sides which encompass the ground-level facts of life of any large convention center: the exhibitor hall, the restaurants, the hotel lobby, the logistics end of things.

For many floors upwards, the atrium continues. The pyramid gradually transitions from big ballrooms and lecture halls to smaller lecture halls, conference rooms, and breakout spaces. Above the several floors of the convention center are the many floors of the hotel proper, with their hallways looking in towards the atrium. The outside faces of the hotel rooms are the outer walls of the pyramid.

The hotel rooms stop level with the top of the atrium’s pyramid, and are surmounted by a floor for mechanical and logistical usage. This floor provides access to a catwalk at the top of the atrium, mostly used for changing lightbulbs.

Above the mechanical floor is the peak of the outer pyramid, which is set up as a large bar with views of the surrounding city.

Questions that need to be answered

These are all aspects of one more-central question: How grand is the convention center?

If I get the proportions too small, the convention center atrium becomes a tiny, claustrophobic space. If I get the proportions too big, it becomes a cavern unfillable by any human population.

How large a human population is large enough? I asked a friend who’s helped run a largeish anime con: 23,000 attendees at their convention. Other “large” cons run in the 20k-30k range, according to various shallow googles, with the biggest topping out near 100k.

So I’ll aim for 30k guests at this convention, in this convention center, which means that I should plan for 40k people’s worth of space across the various rooms, and then have lots of overflow space in the hallways.

On the populations of rooms

Using the room dimensions provided in this floorplan of the Atlanta Mariott Marquis, a 25,000 square foot ballroom can hold 2,500 people in theatre or reception configurations. The 10 square feet per person numbers hold up for smaller rooms as well.

Ballrooms should be at least 100 feet wide by 200 feet long.

On the rail station

Since I’m leaning towards “grand”, this station will be built to the AAR Plate H loading gauge, which is designed for freight rail with double-stacked containers. The total envelope is 9’11” wide and 20’2” tall, if you want to draw it as a rectangle. It’s a huge loading gauge, and I’m using it here to allow this idealized transit system to be used for freight within the city in addition to passenger transit. Also, 10’ by 20’ is a nice round set of dimensions.

On amenities

A convention center and hotel needs, in addition to the revenue spaces, the following:

A rail station needs:

I’m tempted to handwave away all the track-related stuff by putting it into a defined area in the map and saying “Yep, that’s where the tracks go,” but the track placement affects the loading docks.

On resources

I’m basing these plans in part upon:

The Luxor Las Vegas was not a consideration in the planning or layout of this structure.

A Ground Floor Plan

River <polyline points=" Ballroom A Ballroom B Store A Store B Store C Store D

This gesture at a floor plan shows the approximate scale and layout of the convention center's ground floor. The nine squares in the center of the building represent the areas open to the train platform below: these are 40 feet square to match the widths of the track areas. Each track area is 40 feet wide to allow for three train tracks: two platform tracks and one thru line.

The containing square is 280 feet to a side, and draws the bounds of the walkway outside the atrium.

The goal was to have the building's width be twice the width of the atrium; the ballrooms A and B on the north and east sides of the building are 140 feet wide as a result.

If you’re looking at this closely, you’ll have noticed that I allowed that promenade bounding square to accidentally define the edge of the atrium; I need to redo this so that the atrium only stretches from the corners of the bounding squares.

An Improved First-Floor Floor Plan

When I started to redo the above floorplan, I realized that having the ballrooms and exhibition halls be part of the main structure of the pyramid would give it very thick exterior walls, more than 150 feet thick in some places. Setting aside 10 feet for an internal hallway, and having hotel rooms open onto the atrium, I still can’t justify having 70-foot-deep hotel rooms. The proportions are too awkward; something closer to 40 feet is more in line with the blueprints I’ve found.

If the ballrooms and exhibition halls are no longer placed within the structure of the pyramid, then the pyramid’s walls can be as thin as usual conference rooms need to be. It’s rare to see a conference room more than sixty feet deep on its longest axis.

The above floorplan also suffered from a lack of knowledge about where the roads would be placed outside the building. I’ve resolved that below.

River riverfront busway bridge from station to exhibition hall Ballroom (sunken by ~20 ft) Exhibition hall Separatable room pod A pod B Store A Store B Store C Store D Store E toilets toilets toilets front desk Fancy Restaurant E E E E

Hotel lobby is on the east side, with check-in forming a wall between the drop-off and the main circulation area around the atrium. This wall of desks and office space channels visitors towards the fancy restaurant, the elevators going up, or the big ballroom.

Elevators are located in the middle face of each atrium wall, with the north and south elevators only covering the convention floors and the train station's center platform.

Pods A and B are each a continuous space, which can be separated with baffle-walls to make them into separate chunks.

Toilets located in NW, NE, and SE corners. SW corner has bathrooms, but they're back-of-house, and part of the behind-the-scenes connection to the exhibition hall and its loading docks.

The exhibition hall is connected front-of-house to the convention center by a ramp that leads to the mezzanine level of the train station. This ramp also has a set of stairs and escalators leading from the ramp to the ground floor of the convention center. Accessible access is provided in the form of the south elevator. Alternately, surface-level sidewalks may be used, paralleling the dashed line indicating the path of the dedicated riverfront bus line.

The river side of the exhibition hall can serve as a bus terminal for the train station, and the buses here have a dedicated road.

The convention center itself remains rectangular, even if its accessory buildings do not. I’m pretty happy with how this turned out. Now to translate it to another 3d modelling program.

In terms of the earlier questions:

So now it’s on to a new set of questions:

These questions are all different ways of framing the same question.

To help illustrate that question, here’s a pencil-on-paper diagram:

on graph paper gridded five squares to the quarter-inch, with thicker lines on the quarter and half inch, is drawn a cross-section of a pyramid. The base of the pyramid is clearly the train station as described, with three channels for trains in each 40-foot-wide track area, and 40-foot-wide platforms. From the center, the atrium pyramid is 100 feet wide, and this point is marked. From the center, the outer pyramid is 200 feet wide, and this point is marked. From these two points are drawn a number of points diagonally upwards to a line running up the center of the pyramid. These lines are at various slopes. The inside lines show a 1:1 ratio of width to height, 1:sqrt(2), 1:sqrt(3), 1:2, and 1:3. The outside lines are 1:1, 1:sqrt(2), 1:sqrt(3), and 1:2. A scale beside this set of lines shows the heights of various floors.

This is a cross-section of the pyramid. You can see the train station at the bottom of the drawing, and the baseline of the pyramid. The diagonal lines running from the inner edge of the atrium and outer edge of the building go to various heights for each, chosen based at the ratio of width to height.

The chosen height ratios are 1:1, 1:√2, 1:√3, 1:2 and 1:3. 1:√2 makes each face of the pyramid an equilateral triangle. 1:√3 makes the face's height twice that of the base's width.

How tall is too tall? How short is too short?

Now I need to put these in a modeling program.

The Minecraft Models

Earlier, I had tried to build a convention center at the scale of one foot to one block. I wasn’t even sure what the proportions of the pyramid would be, but it did help with the later architectural drawings shown on this page.

Also, I ran out of space. Minecraft’s unmodded maximum height is 255 blocks, and I quickly hit the top of the world when trying to build at the 1 block : 1 foot scale.

The following architectural models are built at the scale of 1 block : 5 feet, which means that the 400-foot width of the convention center comes in at 80 blocks, and the atrium’s inner width at 40 blocks, with a 20-block radius for the atrium’s square. By building out of blocks, rather than mathematical constructs, I have to warp the math to accomodate the setting, which is why in the following images you’ll see numbers that don’t quite match to the cross-section drawing above.

width:height height (ft) height (blocks)
1:1 100 22
1:√2 141 31
1:√3 173 38
1:2 200 44
1:3 300 66

Now I just need to build them.

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