Diagram of a diagonal or single-quadrant junction. The two roads that intersect are in <span style="background:red;color:red;font-weight:400;" title="red"><span style="visibility:hidden; color:transparent;">00</span></span> red and <span style="background:blue;color:red;font-weight:400;" title="blue"><span style="visibility:hidden; color:transparent;">00</span></span> blue, the ramps are in <span style="background:Rgb(0 192 0);color:red;font-weight:400;" title="Rgb(0 192 0)"><span style="visibility:hidden; color:transparent;">00</span></span> green. The black border indicates an overpass.
<a href="//commons.wikimedia.org/wiki/User:Una_giornata_uggiosa_%2794" title="User:Una giornata uggiosa '94">Alessandro Antonelli</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>