Without this change, traffic in SimCity4 was almost as bad as SimCity2013. NAM added congestion avoidance logic, so vehicles could take longer routes if that yields shorter times. RushHour added one ways and the ability to query the paths chosen during the current timeslot. The only thing slower traffic means, is that your driving budget is used up and you can't go as far. Traffic moves slower on congested roads (but doesn't stop until capacity is exceeded by a crazy amount). Then a road is congested based on how many vehicles chose it compared to its capacity.

In SimCity 4, vehicles decide which road they're going to take each 12 hours (go to work/go home). In SimCity2013, agents actually have to stop at stoplights and execute turns when the lane is free. imagine if SC4 had the worst and most inaccurate traffic prediction patterns due to taking into account all these wrong pieces of information and unrealstic driving behavior, and that would be what its like if you transferred SC2013's traffic logic into some kind of algorithm for predicting traffic. all of this makes the 'ideal' of doing an agent/car simulation much worse than doing just algorithms of traffic and just rendering vehicles on the road to show this.Р”Р„gent-based traffic simulation is much better in theory than just faking it using algorithems, but without the stuff above the agent-based sim ends up working less accurately and less smoothly than just using algorithms to predict traffic patterns. it works great when everything is ideal in conditions, but the lack of being able to do one way streets, the fact that the agents freuqnetly bug out, the fact that cars don't actually drive to destinations (they drive randomly around the city till they find an available sink), the fact that the driving logic needs serious improvements (huge congo line of cars trying to make a left u turn ends up blocking the whole street, cars don't bother trying to overtake other cars in the completely empty right lane if they happen to be stuck in a congo line, etc), the fact that you can't control light timing and bus routes in ADDITON to the fact that lights don't support crucial elements such as left turn signals under congested traffic, etc.

This is where SC2013 falls apart somewhat. The huge downside to SimCity 2013 though is that in order for the agent-sim method to be truely accurate, the cars had to be intelligent enough to not bug out, be able to find routes on their own, and there had to be enough nuance involved in road systems, turning laws, etc to account for actually car-level simulation. The big advantage of SimCity 2013's agent simulation was that actual cars were supposedly being simulated, instead of prediction via algorithms, and they followed real world traffic patterns with day/night cycles that involved things like rush hour effect and everything else The cars themselves weren't usually things you'd be able to follow around the map and such. SC4 used traffic algorithms that (I think) are derived from real-world traffic prediction patterns, and simply made streets appear congested with cars if the algorithm went 'this intersection is going to have lots of traffic'.

Simcity 4 rush hour