I've never been good enough at this to warrant going past roads but now that I need to expand I'm starting to get my ass kicked. :P While I have a few specific queries I named the thread as such to leave it open to ANY problems or tips traffic related.

Right now I'm having trouble transitioning. I was in luck making my 1st road an avenue so when a highway was called for all I had to do was pull up the ave and place the HW but it won't let me make a bridge with that and don't even get me started on ramps! :P I'm generally having trouble with highways in general. I know bus stops help but is there a limit? Also I read on another fan page that not clumping areas together helps ie: Not one large residential area but rather several small ones joined by avenues and highways. Any thoughts? :D

ONE MORE THING: Regarding NAM there is an option of road 'underpasses' and I can plot the entrance and exit but I have no way of knowing if the two join. Should I assume they do because that would make things so much easier.

I don't use highways so much, but my impression is that they are best for inter-city travel (as opposed to intra-city). When designing a residential area, I try to make it so that the residents are funnelled from streets -> roads -> avenues -> highways, where the highway will lead them to a commercial/industrial area. The layout kinda depends on the capacities I'm using for the road networks (I find the default Maxis capacities to be intolerably small for any city that is above a few thousand sims).

I tend to forgo buses in favour of other mass transit options (unless it's a small city). IIRC, only R$ really use them and they don't contribute to road congestion. I find subways to be indispensible myself - putting stations in the right places (the traffic data view is a big help here) can significantly reduce congestion problems.

One last note is that the commuter shuttle ordinance will help reduce the number of cars, but the carpool ordinance does not appear to work at all.


Now for my own question - what problems exactly does traffic congestion cause? I say this because in my more badly designed cities there are several badly congested roads, but the consequences beyond crashing automata are not obvious.

I can probably answer a few of these. I'll have to condense the quotes, forum software doesn't like multiple quotes from the same post. Highways:
Not entirely sure what you're asking here, but I'll give it a shot. Highway (Both Kinds) has much more restrictive construction requirements than Avenue does. Bridge building is of particular note as you need to construct your own abutments, there's no Elevated Deck bridge variant. Use the terraforming tools to get the ground high enough, and remember to leave enough space for the inclines.

Also keep in mind that Sims can't get on or off Highway except at Ramps and (this one's a bug) Bus Stops.

Bus Stops:
Nope, although literally every other transit type is better. Although if you have the NAM installed, Busses contribute to congestion.

Clumping:
It can help, but it results in rather unrealistic cities. If you've got the NAM installed, Sims are smart enough to find the fastest route to their destination and will re-route around overly congested routes.

Underpasses:
Ah, FLUPs. No, they don't automatically create a route between the entrance and the exit, you have to build it yourself. Use the Tab Key to find the pieces to build the tunnel. There are concrete vents on every tile where the tunnel crosses an edge.

I would not recommend using them as they are very easy to mess up and quite limited now. Use the overpasses instead. Buses:
This is more true of Subway and Elevated Rail than Buses. All wealth levels can (and do) use all available modes of transit, it's just some will prefer to drive or pretend they're at Disneyland.

Carpool Ordinance:
I can confirm that it does literally nothing other than take your money. Why Maxis left this one in and not one of the other ones from the laundry list of planned-but-removed Ordinances (They planned about 40, we got half that), we'll never know.

Congestion
They're not obvious. It blows out the commute time, making your city less attractive to business by reducing demand and desirability. I think. Z at SimCity4 Devotion would be a better guy to answer this question, he lives and breathes SimCIty 4's transit simulator. He probably knows more about how it behaves and misbehaves than the devs that wrote it.

I'm writing all of that down, especially the Highway thing. I was having trouble working a bridge in with mine and thought I was missing something obvious but now I know it's a pain in the ass to begin with.

Stuff like this is why I live in this forum! THANK YOU :D