Simcity Blog: Paving the Way: SimCity’s Road Tool

Via Simcity Blog

When I started working on SimCity, Will Wright had an observation for me. “Roads” he said, “Roads…are hard.”

And oh, man, were they ever. What’s more, they’re fundamental.

In previous SimCity‘s, the grid controlled spacing and orientation. In the new one, that job is handled by roads. You use roads to structure your city, to space and orient your buildings, to set up transportation networks and to give it shape.

Pedestrians walk on roads, cars, trucks and service vehicles drive on them. Power is carried by them, sewage and water travel under them. Buildings are snapped and oriented to them. Roads are the connective tissue for your city.

First, some technical details.

Under the hood, SimCity‘s roads are a kind of curve called a Hermite Spline. The spline is how the road is represented in the underlying simulation. All the zoning, traffic lanes, road geometry, terrain modification and the rest is built on top of the spline.

The spline is a full 3D object, so you can have layers of roads on top of each other.

When you’re drawing a road, you’re really creating a spline network, and when you intersect the roads, you’re actually reticulating splines (dividing them into a net or network). Seriously.

You have a bunch of different options for drawing roads. There’s a tool for making straight roads that go from point A to point B. There’s another tool for making rectangular road squares. Another tool lets you make sweeping arcs, another one lets you make circles. And my favorite is the curvy road tool which lets you draw out freeform wiggling roads.

When you’re drawing roads, you can hold down the shift key to constrain them, so that intersections will be perpendicular, or that the square road tool draws perfect squares instead of rectangles.

There are different sorts of roads, too – going from dirt roads up to six-lane avenues with streetcar tracks.

Different roads support buildings of different densities. Dirt roads will only ever develop low-density buildings, while high-density streets or avenues are capable of developing skyscrapers.

Roads come in different widths – there are the 24 meter wide streets and the 48 meter wide avenues. The avenues can carry more traffic.

You can upgrade streets too, so you might lay out your city with dirt roads and eventually turn them all into high density streets.

Going from streets to avenues takes a full demolish and rebuild, though.

When they intersect, the higher capacity roads have right-of-way over the lower capacity ones, stoplights and stop signs are automatically placed accordingly. Keep that in mind as you design your cities.

It’s important to know how far to space your roads so that there will be enough room for buildings to develop. For that, you can turn on road guides. The guides appear when you hover over an existing road for a moment.

You can follow them so that your new roads will be optimally spaced.

You can temporarily toggle the guides on or off by holding down the Alt key while you’re using the road tool.

Different roads support different density buildings, so the guide distance changes appropriately.

From further out.

Or closer in.

Roads will try and fit the terrain that they’re on. If you’re doing a road draw that requires a tunnel, you’ll automatically get a tunnel.

If both a roadcut and a tunnel are called for, like with this terrain:

Then you’ll get both:

If you’re doing a draw that needs a bridge, you’ll get a bridge.

But if a road can work with just a roadcut, then that’s all that it will do. It’s cheaper.

You can snake roads up the sides of steep hills.

Or just climb it with roadcuts, bridges and retaining walls.

Roads will automatically make bridges when they cross water. If your bridge happens to pass a navigation channel, it will arch upward to allow ships to pass underneath.

Each road type has its own associated bridges, which can have their capacities upgraded just like roads can.

You can also opt to upgrade your bridges with more attractive ones, if style is important to you.

So there’s a quick overview of roads! We’ll be giving you tips and tricks for using them as we get closer to ship date. Thanks for reading!

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