The Long and Winding Road

When it comes to the environment in a driving simulator, there’s one thing you absolutely must have: the road.

In addition to the road itself, an effective driving simulator must also have a good roadway environment. The environment includes all kinds of objects we see everyday, everywhere we go: buildings, foliage, barriers, signs, pedestrians, other vehicles, signals, etc. And within the simulation, all these objects need to be anchored to a common component – you guessed it, the road.

So what does this have to do with STISIM Drive? Well, you should already know that all STISIM Drive roadway environments are constructed using the Scenario Definition Language (SDL), which means the best place to start when constructing your scenario is with the SDL’s Roadway Event (fun fact: the Roadway Event has more than 50 parameters you can use to define how your road will look).

You can set these characteristics for each section.


For now we’ll give you a quick overview, but you can see a detailed list of all the Roadway Event parameters in the SDL help file found at C:\STISIM3\Help\SDL_Events_Manual.pdf.

Building a Roadway

These are the different roadway sections.

Think of the roadway as a collection of long strips, each with a different purpose, and each with its own set of parameters that you define. In the image on the left, you can see different roadway sections: left and right-side pavement, shoulders, foreslopes, ground, center median, and stripe sections.

Integrating a Roadway Event Into the Simulator

There are a couple of interesting things to note about integrating a Roadway Event into your driving scenario. First, no matter the length of your scenario, when you use the Roadway Event, your specified attributes will remain in effect until a new Roadway Event is specified. What that means for you is that you can use a single Roadway Event for a 100-mile drive, or you can change the look of the road every mile by adding new Roadway Events with different parameters.

No matter how the road curves, it’s easy to line up your objects.

Second, STISIM Drive doesn’t use an orthogonal cartesian coordinate system. Rather, the coordinate system is defined by the geometry of the roadway’s center stripe. The stripe serves as the longitudinal position axis, and the lateral position axis is always perpendicular to the longitudinal axis.

What that means is when the roadway curves, the longitudinal axis curves, too, and the lateral axis will always be perpendicular to the roadway’s center stripe, no matter which way the roadway curves. This makes it extremely easy to line up all your roadway objects based on their distance down the road.

Now that you’ve had a quick primer on the SDL’s Roadway Event, you can start building! We also recommend that you check out the Curve and Hill Events that can be used to add complexity to your roads – otherwise your drivers will only go in a straight line.