In early 2020, my friend Christian Cowgill and I appeared in the first American season of LEGO Masters, a reality-style building competition show. For Episode 6 of the series, “Need for Speed/Super Bridge” (3/12/2020), Christian and I created the “Arch & Truss” bridge, a double-support structure built to span a 6’ (183cm) gap and hold as much weight as possible.
This 7-hour challenge put teams’ engineering expertise to the test. With so little time to work and a blatantly quantitative assessment at the challenge’s end, there was very little room for error in this challenge. Every choice we made could be the one that catapulted us to victory… or else sent us to the bottom. The stakes were high even without the Golden Brick being up for grabs once more!
Read on for my special dissection of this model’s process, design choices, and more.
Challenges of the Challenge
In this week’s build, every team was presented with the same set of tall, black pillars. These formed two sides of the chasm across which we were required to build a bridge. Aside from the obvious limitation of time placed upon us, we were also given another few restrictions and standards. All participating bridges needed to adhere to these guidelines:
We were not allowed to build straight across from one lower support to the other; we had to arch or angle up to the roadway.
We were not allowed to build more than 4 studs in from each edge of the roadway; in other words, we had to leave the roadway unobstructed, except for skinny guard rails on either side.
Anything that we built up and over the roadway had to have a 12” (30cm) clearance below it.
We needed to leave at least 8”x8” (20x20cm) gaps from above, so that we’d be able to load weight on.
The roadway of our finished bridge had to end up completely level with the surface of the two pillars.
For Christian and me, the toughest of these rules to contend with was the restriction imposed on the pillars’ top build surfaces, which were limited to those 4-stud-thick strips on either side. While it would have been easier by far to build our bridge deck directly on top of these pillars, and use the pillars’ lower support advantageously, the rules of the challenge precluded us from taking this route. Consequently, any road we were going to make had to be supported, at least in part, from beneath the top lip of the pillars. This necessity guided us towards building an arch as the lower support structure of our bridge.
The 12” clearance rule, in its turn, determined the size of our trusses up above. The vertical clearance we had to achieve led us to creating enormous triangles. The rule about leaving holes in the top of the bridge through which we could load weights—as well as, I’ll admit, a shortness on time!—unfortunately precluded Christian and me from connecting our two truss systems together as much as we would have liked.
Color and Design Choices
Christian and I saw our build for this challenge almost like a sequel to our Mega City model from the previous week. One of the core themes we explored in that build was about the transition from old to new, of refurbishing older structures towards newer purposes. We envisioned this bridge as telling a similar story, starring an aging stone arch bridge getting retrofitted with a more modern, trussed reinforcement. It gave a bit of storytelling justification to our unorthodox choice to include two support mechanisms.
We wanted to highlight the old/new dichotomy we’d settled on through color. So, we employed a motley mix of tans and greys to build up the bridge’s stony lower half, and settled on bright yellow for the trusses. Yellow felt like the best choice for us for a few reasons. First, many of the Technic elements we needed to use came in this color; second, yellow made for a vibrant contrast with the earth tones of the arch; and third, none of the other teams were using yellow as a primary color.
We also—mostly inadvertently—reinforced dichotomy on the bridge by the types of elements we used above and below the line of the deck. Below, the stone arch was built mostly from traditional LEGO shapes like bricks, plates, and slopes. Above, the trussed supports were constructed almost entirely with Technic pieces. By putting these two elements together, we ended up with a cool and dynamic-looking structure.
There are three major, structural components to our bridge, each of which was designed to provide a degree of strength to our roadway: the arch, the beam, and the truss system. I’ll discuss these each in turn now.
The Arch
The arch of the bridge was difficult to achieve, given the limited assortment of slopes available in the LEGO vocabulary. It was impossible to make an arched shape entirely from slopes, anyway, especially at the width we had to accomplish. So midway up, we turned to stacked plates, each layer protruding forth as a corbel on which another sat. I mostly relied on “eyeball math” to accomplish the proper curvature, here, and I do think the arch looks a little flattened as a result. Christian filled and reinforced inside the arch, doing well especially at the pillar sides to give us rock-solid foundations.
However, as we came to move the bridge’s deck into place, we realized we had a bit of a problem; the deck had to slot in from below the level of the pillars, while the arch had been built up to meet that same level. We ended up with a three-brick-tall gap that we had to fill between them, but couldn’t easily access, because both above and below it we’d already built strong structures. Whoops! We did our best to wedge bricks in between the deck and the arch, but this gap nevertheless became our bridge’s weakest point and definitely curtailed the efficacy of the arch.
The Beam
The first thing I built on this bridge was its beam. I knew that this component had to be rock-solid by itself, because this was where the weight would get loaded onto. Even if the support structures above and below the deck were powerful, they’d count for nothing if our weights just fell right through the bridge.
I made the beam as a complex, poly-layered lattice of plates, bricks, and Technic connectors. Railroad tracks formed the core of this complex lattice. I used these infamously large, inflexible parts to show the Brickmasters how we’d learned from past challenges. In the Space Smash episode, Christian and my use of railroad track bricks lent our exploding space station undesirable stability. In the Super Bridge challenge, on the other hand, stability was the name of the game, so I thought to turn to these elements again and exploit their strength (this time, purposefully)!
The beam, which turned out to be nicely hefty, strong and sturdy, hung beneath our two layered guardrails. I did my best to make sure the rails—which were only four studs wide apiece—were extra-strong, with as many long bricks and plates as I could use. They ran from the far end of one pillar to the other, spanning not just the length of the chasm but the full length of the bridge. We left exposed Technic bricks on the guard rails’ sides, as well as on the sides of the beam, so that the two could be “riveted together” at regular intervals by short Technic beams.
The Truss
The truss came together rather last-minute, and to my regret it didn’t add tremendous stability to the bridge. I think, if we'd had more time, we would have been able to not just reinforce the spars of the truss—which, out of necessity, turned out to be rather flimsy—but also to include more triangles at other critical junctures like in the middle, up above, etc., and to build up more vertical reinforcements from the guard rails.
Although we included lots of yellow, the other colors on the trusses turned out to be something of a hodgepodge. This was due, quite simply, to the fact that by that point in the 7 hours, with six teams using a lot of the same bricks, there just weren’t many Technic beams left to go around! Even in a “bottomless” brick pit, sometimes parts were in such a high demand that we couldn’t get the colors we wanted.
Nevertheless, I think the trusses looked pretty great, and instantly helped our bridge look impressive. We accomplished far greater height than any of the other teams, and gave our bridge a signature silhouette.
Minifigs at Work!
In an attempt to add more story to a build that was essentially all about stability, Christian and I peppered the bridge with construction workers. Painters are trying to “cover up” the slapdash colors of the trusses, while other members of the crew are wheeling excess waste off the soon-to-be-opened bridge. We love minifigures, so relished the opportunity to include a few as finishing touches on our model.
My favorite pair of minifigures is a representation of me and Christian. A burly-looking construction worker is wheeling a bespectacled one away in a wheelbarrow. I’ll bet you can’t guess who was who…
Putting on the Weight
Christian and my bridge was first to get tested, so the number we achieved determined the “weight to beat” for other teams, at least to start. Our private estimate, going into the judging, was that our bridge would be able to hold anywhere from 150-200 lbs (68-90kg) of weight. The bridge we had built wildly exceeded these expectations, and turned out to be able to hold 445 lbs (201kg)!
Putting on the weight was a nerve-wracking and exhilarating experience. Thrillingly, we ran through all the kettle bells provided by production, and had to start dipping into weights and sand bags from the camera department! However, since Tyler and Amy went after us—and since nobody thought in advance that teams would need to use the flat metal plate weights they ended up having to use to hit their 1,000 lbs (454kg)—Christian and I had to use only the unstable, round kettle bells to make the foundation of our bridge’s weight system.
I believe, had Christian and I gotten to use those rectangular and evenly-distributing plate weights—which could also derive some stability from leaning their edges into each other—rather than the kettle bells, we might’ve scraped a number higher than 445. I doubt if we could’ve hit 1,000 like Tyler & Amy and Mark & Boone, but I still would have loved to have loaded our bridge using some different, flatter weights.
Still, 445 is not a number to scoff at! Christian and my bridge held more than twice as much as we’d dreamed it could. I was over the moon with how we did, and I’m extremely proud of our work on this challenge.
Thanks for reading! If you have any other questions or comments about this model, feel free to leave them in the comments below.