Other transportation systems help loss of high congestion and traffic pollution.
Highways are high-capacity roads. These are meant to be used in large cities to quickly get between places, however due to the nature of the commute paths taken it is hard to use them effectively if you do not plan them out before you start your city. Zones cannot connect to a highway and neither can pedestrians walk on one.
You'll need to make long curves if you want to make highways turn, as they cannot have instant turns like roads and streets do. They can connect directly to the rest of the road network using avenues to "end" them. Onramps can be created for roads by selecting the option in the highway tab. Avenues can get onramps by making an avenue go under a (raised) highway and a dialogue will appear giving you the option (works for roads, too). They can also connect to each other and form cloverleaves (however, these are huge and take a lot of room).
|Construction Cost||§150||Capacity||1,000 passengers|
|Maintenance Cost||§5||Capacity Cost||N/A|
A bus network is the easiest and cheapest way to create public transportation. Simply place bus stops around your city and people will travel between them (the concept of bus lines does not seem to exist in SimCity 4).
Since public transportation is used mostly by poor people you should place bus stops there, as well as at potential sources of jobs (like industrial areas). Sims do not walk far, so the bus stop must be close to be used.
|Construction Cost||§500||Capacity||2,000 passengers|
|Maintenance Cost||§20||Capacity Cost||N/A|
Due to its high costs, the subway is meant for large metropolises where a bus network would be horribly overcrowded.
To build a subway network, you'll need to build a set of subway lines and connect all the stations with each other. Subway lines have problems with steep hills, especially when crossing rivers, so try to move the lines around a bit if it won't build the line where you want it.
The airport, besides decoration, has one main purpose: boosting the commercial demand cap. As they're very expensive to maintain and only really benefit offices, you should wait for them until your city has grown sufficiently large.
At the beginning, you'll have a choice between a Landing Strip, a Municipal Airport, and an International Airport. They'll start up small at first, but if they reach their capacity, you'll be asked to upgrade them, first from Small to Medium and then from Medium to Large. These upgrades are expensive so watch your budget before agreeing to one.
The seaport is there to ship freight out of your city. By nature, it must be built at the shoreline, and it will only be used if it's the shortest way to get freight out of the city (so building it next to the city border is rather pointless). Due to a bug, the seaport does not benefit the industrial demand cap.
When you try to drag a road or rail across a body of water, it will create a bridge. However, it can be quite difficult to make one appear because they have some quite specific requirements in regards to the terrain. No roads can cross bridges and streets can never form a bridge. You can, however, use tunnels to go under the bridge if desired.
Trying to drag a road or rail over a high hill or mountain may result in the creation of tunnels. These make the traffic move through while leaving everything above intact. The requirements for a tunnel are only checked when you build one, not at any time once the tunnel is there, which can lead to some amusing effects (like the "underwater tunnel", made by lowering the terrain where a tunnel is until it becomes a body of water).
Streets cannot form tunnels. As well, pedestrians cannot enter a tunnel.