WHAT ARE THE FENCE-ARCHES?
Have you ever noticed (or used!) the "Linking Logs Trellis Arch"? It's the very last icon in the Fences catalog. No? Me neither
But it's a pity, because that is the only example of Fence-Arch in the game. Its special feature is that it can be laid down like a fence, but can be built even over an existing fence, so to create unusual entrances and gateways. However, this fence-arch is rarely used because it comes in only one colour and only one shape: it only matches the brown "Pinegultcher" Maxis fence.


HOW TO INSTALL: IMPORTANT!
In order to use the custom Fence-Arches, you need to install the Scriptorium (v. 2.2 or later), with the option "Custom Walls-Fences-Arches" activated.
When done, install the files as follows:

• unpack the archive "FenceArches_DownloadsFolder.rar" to the Downloads folder;
• unpack the archive "Fences_DownloadsFolder.rar" to the Downloads folder, too;
• double-click on the shortcut "Scriptorium_Walls-Fences-Arches" (located in the Downlaods) and a Scriptorium window will open up: you will see the note "-- Put here all the custom scripts for Walls, Fences and FenceArches";
• unpack the archive "FenceArches_ScriptoriumFolder.rar" to the open Scriptorium window.

WHY THIS SET?
I confess: I'm posting this set because no one so far has posted custom Fence-Arches And I also wanted to expand the "Pinegultcher" set, so to make it actually usable. Maxis, as usual, is no good at creating matching sets: the game contains the gates in 5 colours, but the fences come only in 2 colours, and there is only 1 fence-arch... TSK! TSK!
After installing these files, you will have a complete Pinegultcher set:

Apart from the well-known "brown" colour, you will have 4 more colours to choose from:

Please note that the set includes two different versions of the Fence-Arches:

• Standard Fence-Arch with posts at each tile (Maxis mesh);
• Suspended Fence-Arch with posts only at the sides: this is useful to create covered areas, such as dining terraces, or covered driveways (see attached screenshots, below).

HOW TO USE THE FENCE-ARCHES
Very simple! They are laid down just like any fence; the mesh is updated dynamically, while you drag the fence tool:

If you create a covered area, it will be normally usable (you can place objects under the arches, and the sims will be able to use them). Only the driveways require the moveObjects cheat to be placed, but then they work fine.
NOTE - The sims will walk through the posts of the suspended arch: this is not a bug, I had to do it in order to make the underneath area usable.


GAME COMPATIBILITY
All the attached fences and fence-arches are compatible with ANY game, including the base-game only.


CREDITS AND ACKNOWLEDGEMENTS
Credits to Maxis, for the original mesh of the fence-arch (the suspended version is a variation over the Maxis mesh); half of the textures used are by Maxis too (they were 'lost' in the game files).
Thanks also to Niol for discussing with me this interesting subject, in this thread.

Polygon Counts:
The fence-arches are modular: the various pieces are dynamically joined while dragging the fence tool; while it's impossible to declare a poly-count per tile (because it depends on how wide is the fence-arch), you can have an idea reading these figures:

1. A 3-tile-wide "standard" fence-arche (with posts at each tile) uses:
   4040 Faces / 4886 Vertices (average: 1346/1629 per tile).
   The poly count is identical to the original Maxis fence-arch.
   
2. A 3-tile-wide "suspended" fence-arch (with posts at the sides only) uses:
   3538 F / 6128 V (average: 1180/2042 per tile).