One of the biggest PITAs that CAW builders have been dealing with for eons now is routing on bridges. For no reason that can be explained, tons of sims will keep getting stuck on bridges. In the worst case of scenario, you might have as many as a dozen of them trapped before the first sim week is out. Well, I discovered one potential issue and fix, and it has to do with the non-terrain paints in CAW--routing (blue paint) and camera (yellow paint).

There is a third paint, "steep terrain" that is marked in red. However, unlike routing and camera, you don't have a choice of painting it. CAW does it automatically depending on how you sculpt areas.

What I learned is that if you sculpt the terrain under the bridge in such a way where there are either flecks of red paint, you'll have issues with sims getting stuck. The red paint works the same as routing; if there are gaps, uneven paint, etc., sims will route there and get stuck.



To avoid this issue, open your sculpt panel, check "show steep terrain" to bring up red paint. Then, use smoothing tools to adjust the slope underneath your bridges to get rid of the flecks.



You'll know everything is fine if most sims can walk or run across the bridge and get and get off without a problem.



There Will Still Be Some Issues, Though

What fixing the steep terrain paint issue does is keep the bridge from being a magnet for stuck sims, to where you'll have a half a dozen or more constantly stuck on them. However, there will be the occasional sim stuck here and there, and for reasons that I'm looking into. However, I think they might be due to the following:

1. Glitched households and/or lots. I noticed that after I fixed the steep terrain paint issues, the exact same households would keep getting stuck over and over again, and that some of them seemed to be confused as to where to do activities. For example, the kid of one household just sat down in the middle of nowhere to do his homework. So, my suspicion is that there's something wrong with the household or the lot that has broken routing for them no matter where they go, including bridges.

For example, look at the screenshot below. One sim got stuck but the other one got off fine. There was something wrong with the stuck sim, because he didn't even do the stampy thing. He just stood there like a zombie.



2. Vehicles can't spawn on bridges. You know how the game will make your sim randomly walk somewhere, but then it'll be time for work and school and they'll immediately twirl into their work clothes and try to get to work or school? If it's a kid, they'll get on their bike. If it's a teen or an adult, they'll summon a taxi or get into their car.

What I noticed is that if sims are walking on a bridge and it's time for work or school, they will get trapped on the bridge, because the routing on bridges is different than it is for roads. Sims can leave the sidewalk to walk on the road to summon a vehicle. They can't do it on bridges, so they get stuck there.

I read in many places that something happened to bridges after Pets, and perhaps what happened is that they changed something to where bridges were made to stop acting like roads. I guess the logic was that it would force sims to act as pedestrians on these bridges because otherwise, they would never use them as such. It kind of makes sense if you think about it. All sims want to do is just hop onto a vehicle or use a subway. If the bridges behaved like roads, you would never see sims as pedestrians. They would always just drive and bike to where they want to go.

To emphasize, I don't really know what happened to bridges that they'd get borked. I am just estimating that this is what happened. In any event, the point is that even if you eliminate 99% of the stuck sim magnet issue, it seems as if you'll always have the occasional straggler getting trapped.

Yes, it was definitely pets- the horses especially have problems on bridges. I had a perfectly working bridge in a pre-pets world I made, but after Pets the wild horses would foreverbe stuck, and sims occasionally went across the water!
Thanks for the solutions and the clear images, most helpful!

@simsample: Thanks for confirming the Pets thing. I didn't start building until after I got it, so I wasn't sure. I am still trying to figure out the other ways that sims might get stuck and what workarounds there might be, if any. If I find anything new, I'll definitely post an update!

Good post! Thank you! I have had sims stuck on bridges also. One thing though is that this game can be frustratingly unpredictable and inconsistent. I have done some tests with absurdy impossible terrain and the sims navigated with no issues. I have some crazy photos somewhere of a sim on a horse riding up a huge sheer cliff. I recently did other tests with impossible, or should be, setups and the test sims had no issue with them.

But as you say, in some other case a red speck can throw things off. (!)

@daisylee: Thanks. Isn't this whole thing maddening?!

I'm still trying to research all this as I type this and discovering things even more maddening.

What I'm noticing is that with the old pier bridge (ugly black bridge with wood pylons), everything works as it should. If a walking sim stops in the middle and changes his or her mind, she is able to go to the center and call up a car or taxi.

But the Suspension Bridge and bridge from Ambitions (the green steel one) are what seem to be giving the most trouble. For instance, in getting rid of the red flecks, sims who go from Point A to Point B without changing their minds are fine crossing over. It's the ones that change their minds or have to change course for whatever reason that get stuck.

I posted some more pictures so everyone knows what I mean:

Scenario One--NPC Sim Changes Into Work Clothes, Gets Stuck

NPC stylist in regular clothes walking to his job. Everything was fine until...



He stopped, changed into his work clothes, and became stuck.




Scenario Two: It Rains. Sims Caught on Bridge Get Stuck
It started pouring outside. Sims who were already on the bridge and over water got stuck. Why? Because they got a new action telling them to "Go Inside" and then "Go Home" but couldn't because they couldn't summon a car or taxi.





But...dramatic music plays...sims who were on their way to the bridge and caught in the rain just outside it were able to navigate and cross fine!





So, this is what the stuck sims on bridges thing seems to be about. Something got borked in the sims' ability to summon vehicles if the game forces them to change gears mid-crossing. Why, I don't know. I've heard people say that they changed the Y axis of the bridge, but that never worked for me, unless they weren't telling the whole story.

I have had sims and animals stuck on the green one many times. I get the notice from Nraas and have to deal with it.