iRacing: The Technical Challenge Behind Creating a Street Circuit

There comes a moment in every simracer’s life when deep questions arise: Why is my Safety Rating tanking?… Why did I think entering Long Beach with an LMP2 was a good idea?… and then, suddenly, an even bigger question hits:

Why on earth does it take so long for iRacing to release street circuits?

And although it may sound like a conspiracy theory, the answer isn’t “because they don’t feel like it.” It’s because building a proper street circuit is a technical monster, especially for a simulator that lives and dies by precision.

To understand why, we need to step for a moment into the jungle. The urban jungle.

The City Doesn’t Forgive (Not the Player, Not the 3D Artist)

Unlike a permanent circuit, where the number of buildings is zero and the number of trees is maybe two, street circuits come with a tiny little detail: An entire city.

And we’re not talking about a few blocks and a fancy 4K banner. We’re talking about kilometers of façades, windows, curbs, manhole covers, patched asphalt, traffic signs, trash bins, concrete barriers, and that one lamppost which always seems to be in the worst possible place.

Creating all of that with laser-scan accuracy isn’t just “copy and paste the map.” It’s an almost surgical process, because iRacing can’t afford a “yeah, close enough.” It has to be exact.

On a permanent circuit, the art team can practically take a nap between corners. A fence looks like every other fence. In a street circuit, every five meters something changes, and that something must be modeled.

Buildings: The Villain

Buildings in a street circuit are like in-laws during the holidays: there are too many, they’re all different, and none of them wants to make your life easier.

Every façade requires:

• unique textures
• windows with proper reflections
• details that can’t be ignored because they’ll show up on onboard cameras

And if someone asks, “Why not reuse buildings?” Because the community would notice.
And they would comment on it. Intensely.

Cities come with another dirty trick: visual depth. When you race through Montreal (often called a “street circuit,” though let’s be honest, it’s more of a park with a track), you have trees behind the barriers. And trees don’t judge you if they’re duplicated.

In a real city, behind the barrier there’s… more city. And if the artist gets a window wrong or adds an extra floor, the simracer will see it and assume the scan is inaccurate or, worse, that the game is “not realistic.”

Vegetation: More Trees, More Time

You’d think trees are easy. Everyone always thinks that. Until Long Beach arrives and you realize every palm tree is modeled individually, because one palm is not the same as another, and certainly not the same as a generic tree pack.

Urban vegetation is:

• not symmetrical
• not orderly
• not logical

A tree grows crooked, another is half-trimmed, another one is dry, another casts a completely different shadow. On a permanent circuit, greenery is placed to avoid causing trouble. In a city… welcome to reality.

Lighting: The City Shines, but Not Always Nicely

Lighting in a street circuit is responsible for about 80 percent of perceived realism.

The problem? Cities reflect light everywhere. Glass windows, metal surfaces, storefront signs, wet asphalt… all of it creates chaos for any rendering engine, especially in simulators where light behavior is calculated physically.

On a permanent circuit, light behaves like a polite guest: sun, shadow, sun, shadow.
In the city? Sun, shadow, faint blue reflection from a glass window, partial shadow from a crooked tree, golden bounce from a building, street lamp glow, barrier shadow, weird tunnel ambient light…

And for you to approach Turn 1 without your GPU launching into low orbit, someone has to calibrate all that manually.

How This Compares to a Permanent Circuit (or a Park-Based One)

Take Montreal as an example. Yes, technically “street,” but in practice it’s a controlled environment:

• few buildings
• uniform vegetation
• repeatable objects
• stable lighting

A permanent circuit like Spa, Silverstone, or Road Atlanta is even more “clean”: surveyed track surface, paddock, some grandstands, a couple of buildings that haven’t changed in decades, and objects you can reuse everywhere.

It’s zen compared to a city.

Now imagine applying that same workflow to Baku, Singapore, or Las Vegas. At that point, the artists start considering a career change.

So How Can iRacing Do It Now?

Because they went through the full gauntlet with Long Beach.

That track was a laboratory full of trial, error, coffee, and probably silent tears.
But from that struggle came new tools, new automations, and new internal techniques that simply didn’t exist before.

Now, when Adelaide, Miami, or St. Petersburg appear on the schedule, the team no longer panics. They approach with confidence.

• Remember, you can join iRacing clicking here.

See you on the track!