I'll start by creating an image which represents a single parking stall. This is done by opening paint and creating a 100 x 200 pixel image and placing a white stripe along one side.
Next I'll go into InfraWorks and create a material that represents a row of parking stalls. I'll select my parking stall image file and set the dimensions to 10x20. InfraWorks will copy my image file to its own location where it likes to store style content.
Next, I'll create a material group that includes the different components that I might need for a parking lot. This includes an aisle, parking stalls, and a white stripe.
Now I'll define a road style using an arrangement of these components. For this example, I'm going to build a parking lot with a center aisle, two double-rows of parking, a pair of outer aisles, and a pair of outer rows of stalls. So working symmetrically out from the centerline that would be a 12-foot lane, row of stalls, white stripe, row of stalls, a 24-foot lane, and a row of stalls (the preview looks funky but the actual result in InfraWorks looks pretty sweet):
Notice above that I only assigned a "type" of Roadway to the aisle, that's it. That will become important with a little trick later.
Now, I can create a "road" in InfraWorks and use my new road style. They look even better when you create a few and use curves.
Then I can create another style for just the aisle part and use that to connect parking lots.
The distortion of the parking stalls while transitioning from parking lot to road is kind of odd, but it gets the job done. Also, remember that I assigned the center aisle of the parking lot as a "Roadway". I used this same assignment for the connector road style and it keeps the transition from getting really crazy.
The styles I'm using here are very basic (for example, just using black instead of an actual pavement texture) but they do the trick nicely. Use this concept to make parking lots that are way more awesome than these!