Yes, this is delayed and I'll tell you why. I fell into that dip on that bit of circular road there and just managed to crawl out and regraded the Roads for you all while I was at it. Now, am I good or what? At not seeing holes, maybe not so much.

What is this?
This is the routing fixes for Twinbrook, similar to the other worlds'.

What has been done?
As explained in the Game Help:World Routing Lags^wiki,

• the yellow spots denote areas where the Sim non-routable and Camera non-routable painting have been repainted over blank spots. This includes at the world edges, too, although it may not be denoted on the image
• the red spots denote areas where the intersections have been corrected so that the Intersection and Road pieces now all connect.
• the light-blue spots are roads that have been regraded and smoothen a tad (with adjoining world geometry also "Smooth - Gentled"). You can see the rebuild routing in the "fixed" image has the routing lines covering more surface area.
  

• This is the dip in the road I was referencing above. What I've done here is:
  1. Regraded the road and smoothen it. Also smooth the slopes to match, though I'm still not that good at sculpting.
  2. Removed the non-routable terrain painting that was touching the roads to ensure the routing encompass the road surface
  3. Pushed all the railings back a tad so the non-routable terrain painting can be pulled back
• The are 2 others spots where the Roads were regraded - refer to the aerial map with the Dotted spots.

• There is a visual way to tell if the fixed resources have been imported, and the fixed world is "Live" in a new game or your Save games.
  • Look at the spots denoted by Red dots - at a road intersection. If you can see the intersections are yellow (instead of blank) from Map View, the fix is applied correctly.

Change in my approach of packaging the fixes
The total size, even after being archived, still exceeds the server maximum 10MB allowed per download file, resulting in 3 parts. With some feedback that folks are still having trouble with multi-part files, I've separated the fixes out into separate .7z files because there are just too many now. So, I've broken them down into the following sets.

Download ALL 3 .7z files and extract them all into a temporary folder onto your Desktop, then import all the Resources in S3PE by selecting all files (Ctrl+A).

Resources modified:

• TwinbrookFixedRouting.7z containing 2 files
  1. 0x05CD4BB3 UNKN World Routing
  2. 0x05DA8AF6 UNKN World boundaries

• TwinbrookFixedRoadIntersections.7z containing 603 files
  1. 0x9063660E UNKN World Roads & Walkways
  2. 0x00B2D882 0x00000001 _IMG DDS Image
  3. 0x01661233 0x00000002 MODL scene Object Model (aka Object Geometry)

• TwinbrookSmoothenRoadGrading.7z containing 192 files
  1. 0x033B2B66 UNKN ?? World Model/Geometry/Terrain/Height map info ??
  2. 0xAE39399F UNKN World geometry

Notes & Changelog:
As and when I get reports of any issues, or new spots, or patch changes (if any).

• Oct 18, 2011 update:
  • Compatible with Patch 1.26.89. Would most likely be compatible with any patches in the future as well.
  • If you had renamed the modified worlds to *.fixed before patching (or installing new add-on), you can simply renamed the pair of them back to *.orig and .world respectively, as the Wiki instructions state
• The 3 .7z files contain a total of 797 (2+603+192) items.
• Compatible with all patch levels up to the current 1.24 (as of Jul 26, 2011).
• Would conflict with any other download that make changes to the .world file that changed the above named resources.

Backup!
Heed that backup instructions, really! You've been warned!


How to install?
Please be sure to read and follow the instructions under "Edit in S3PE" in full in Game Help:World Routing Lags^wiki
The rest of the info is the same, pretty standard - backup, read and follow instructions to the letter, provide feedback, etc etc. All is in the wiki - READ it!


How to remove or restore the file before updating?

• Go to this path
  Code:

  \Program Files (x86)\Electronic Arts\The Sims 3 Ambitions\GameData\Shared\NonPackaged\Worlds\

• Delete the *.world file. Or if you want to reuse it after patching, rename it with a ".fixed" extension, so the filename becomes "Twinbrook.world.fixed"
• Rename the "*.orig" copy by removing the .orig extension (or from whatever you have renamed it to).
• Delete caches before starting game. Game Help:Sims 3 Delete Cache Files^wiki

Feedback
As always, feedback is welcomed.
Please report any other areas that you get stuck Sims at that I might have missed. If I may have been overzealous in the corrections or did some things wrongly.



Additional Credits:
The usual suspects who shared their knowledge in Create (and #create), the various wikis and especially, the Jones for S3PE.