Large One-Way Road Roundabouts: A Guide

[woodb3kmaster]

Have you ever wanted to build an extra-large roundabout, but couldn't get it to look right? The roundabouts included in the NAM are great, but what if you want more than a little 2x2 space in the center? Well, keep reading. In this tutorial, I will show you how to build a large roundabout using OWR-2 smooth curves. When finished, it will measure 10x10 cells in size. You can connect up to eight avenues to this roundabout; the pictures below show six avenues connecting to it, since that was just what I was building at the time.

Before beginning, make sure you have the latest NAM version installed with one-way road smooth curves. This tutorial will be impossible to follow without them. You should also ensure that the ground where you're going to build the roundabout is completely flat, or some of the dragging you'll need to do will trigger an "unsuitable grade" error message and a red drag.

1. Drag four 4-cell-long segments of OWR-2, and plop single OWR stubs next to their ends, in the following pattern:



The terrain in this picture is too close to sea level to tell, but each pair of parallel OWRs is 8 cells apart. Make sure to drag them in the direction that traffic will follow - clockwise if you use LHD, counter-clockwise if you use RHD.

2. Drag diagonally to connect the ends of two of your OWR segments:



The OWR stubs will automatically convert your sharp curves into smooth curves if you drag the right way (make sure not to drag through the stubs).

3. Repeat step 2 three more times to complete the circle:



Believe it or not, this was one of the easier parts of this tutorial. The hard part is coming up next...

4. To connect diagonal avenues to the roundabout, you can't simply drag the avenue right into it, or the smooth curve overrides will break at the intersection. Instead, you have to connect the avenue with double diagonal OWRs. Drag one diagonal OWR from the roundabout to the end of your avenue:



It's important to note that the diagonal OWR connects to the roundabout in the middle of one of the diagonal drags from steps 2 and 3 - right in between two smooth curves.

5. Drag another OWR from the end of the avenue to the roundabout to complete the intersection, and repeat for any other diagonal avenues you want to connect to the roundabout.



The last step is, perhaps, the easiest of all.

6. Drag your orthogonal avenues to the two straight cells in one side of the roundabout:



Unlike in steps 4 and 5, you can drag with the avenue tool here.

And there's your finished roundabout! You can put whatever you want in the middle.

[Seaman]

thank you or sharing the concept. Nice trick with the diagonal entrances. 

[kbieniu7]

Indeed! It might be useful!

[brick_mortimer]

Thanks for the tutorial! 

The way to hook up the diagonal avenues is is not only useful to build a "monumental" roundabout in an urban enviroment (à la Place des Etoiles), but also is you want to build expressways with connections to highways etc.

Thanks a bunch 

[Akallan]

Excellent tutorial '! Thank you!

[metarvo]

You're quite resourceful!  Nice find!