This 18' by 24' pike spans a waterway. The added area is actually a railway in itself that includes continuous-running ovals. Here elevation is a must, not an option. Trains leave the upper level of the original layout, cross water and enter the elevated track. You can use an earthen grade, as shown here, or trestles.
For a water level crossing, adjust trackwork - you can connect from the upper right corner of the bottom layout to the lower right corner of the upper pike.
Here we have an 18' by 30' layout with the two separate ends facing across the right edge of the original layout. Again, the bridge extends from the elevated portion of the first layout to a trestle or elevated portion of the second. You would extend the lower end of the left layout, as shown in a previous section, to give continuous running to both sides of the waterway.
To connect at water level - on the left layout, go to the upper right pier. Add one half curve at the switch, and replace the pier with the end of the bridge. . On the left layout, at the bottom right corner, replace a curved section with a left-hand switch, (You might have to add a half-curve to the oval.) It should meet the end of the bridge nicely. That leaves the elevated section useless. Extend it into a small freight yard. Or you can extend the straightaway at the very left edge and then make a loop, thus producing a semi-dogbone. You would need to put a right-hand switch in place of the curve above the leftmost switch.