I love Improved AI. It really helped me with a lot of troubles. Most parts of my roads where completely useless before, just because Cities really hasn't the best AI.

But there are still some things I noticed, that really get annoying. You might want to consider fighting these problems in a future version:

1. In roundabouts (especially big ones with 6-lane roads (one-way of course)) often cars from the farest away lane (towards the next exit) want to change to the first (nearest to the next exit) because it seems smarter for them. But all they do is congesting all 6 lanes. They change one or two but have some other cars around them, causing all to stop until the one car can change to the first lane. This is basically the behaviour that currently seems to cause all my huge traffic jams. It congests so much that a fluid flow is not possible anymore.

2. Traffic lights are pretty much useless. I currently use them especially in my big roundabouts, cause without it gets even messier. Cars block each other and won't move at all. With traffic lights it's a bit organized. Theoretically it should work perfectly fine. But practically it works different. Sample: I got a big roundabout which leads into the downtown (the most dense part of my city). A one-way 6-lane road leads into the downtown while one comes from the highway and the industrial zone (so damn crowded - sometimes congests back to the industrial zone which is far away). Now there are a lot of cars in the roundabout. They drive towards the downtown exit. The lights change and now a lot of the highway cars should drive to the downtown. But the problem is that the cars which are already in the roundabout do drive until they can't anymore. Means they do congest the whole junction. Now when lights change the highway cars can't turn into the roundabout anymore because the other cars already block it. This goes on vice versa, so basically the whole thing isn't working at all.

It might be a good idea having a third state for the traffic lights, which means they should already stop but the other ones still don't drive. A wait phase. Like with real traffic lights. This should solve about most problems with junctions and roundabouts.


I hope you got what I mean. I would really love to see these features in IAI and Traffic++. These are the only missing parts. Then most road layouts should work fine :)

EDIT: Here comes the third suggestion.

3. It would be nice if cars would switch lanes more smoothly. Right now they stop, do a 90° turn and drive across the lanes instead of driving smoothly in a smaller angle towards their destination lane. Probably difficult to implement, but this is one of the top reason for congestions. They simply don't drive efficient. This across-driving blocks all lanes :-/