Traffic has been "modeled" since SimCity 2000 way back in the 90s. Back then it was a simple capacity measurement depending on nearby buildings, though. There was definitely no concept of a road network and flow.
SC4 was the one that actually tried to model traffic flow throughout your city to locate bottlenecks. The pathfinding algorithm used looks like a variant of A, with the caveat that it would never explore nodes that weren't between you and your destination. This resulted in a lot of finicky behavior - things like your sim not taking the subway to work because he had to walk back a single block to catch it, and insisting on joining the gridlock instead.
This is largely fixed with the NAM mod though, which restored proper pathfinding.
The nice part about SC4 was that you could actually zoom in and see the gridlock. Sure, these weren't actual citizens in their cars, but it is a correct visualization of the simulation's traffic analysis. I for one will gladly give up the ability to follow a sim home for a faster, more scalable, more accurate simulation.
> This resulted in a lot of finicky behavior - things like your sim not taking the subway to work because he had to walk back a single block to catch it, and insisting on joining the gridlock instead.
Reminds me a lot of most consumer GPS today that avoids backtracking whenever possible, even if that means a more congested or convoluted route.
I've seen this behavior too many times, from systems ranging from Google Nav to TomTom to the OEM Nav in my Mercedes.
SC4 was the one that actually tried to model traffic flow throughout your city to locate bottlenecks. The pathfinding algorithm used looks like a variant of A, with the caveat that it would never explore nodes that weren't between you and your destination. This resulted in a lot of finicky behavior - things like your sim not taking the subway to work because he had to walk back a single block to catch it, and insisting on joining the gridlock instead.
This is largely fixed with the NAM mod though, which restored proper pathfinding.
The nice part about SC4 was that you could actually zoom in and see the gridlock. Sure, these weren't actual citizens in their cars, but it is a correct visualization of the simulation's traffic analysis. I for one will gladly give up the ability to follow a sim home for a faster, more scalable, more accurate simulation.