Transportation is the means of how citizens, freight, and passengers get around in the city. Building an efficient transportation system is crucial to a successful city.
Roads are the main components of transportation. All buildings must be connected to the city hall via roads, and certain service depends on a road system in defining it's area of influence. Roads may become jammed due to over use, which can be solved by defining it into a one-way street, changing it to a larger road, and building an efficient system for your citizens to get around.
Fast Lanes differ with regular roads in that they have a significantly higher traffic limit, and rely on special interchanges to create intersections and connecting to regular roads. Fast Lanes are unlocked after reaching 500,000 population.
Public Transports includes buses and metro, is a category of transportation the user can place to reduce traffic congestion on roads. Good placement of public transport will greatly diminish the amount of unskilled and skilled worker's traffic. However, executives and elites will drive, only taking the bus and metro as a last resort.
The Bus Company unlocks after reaching 50,000 citizens, building it will open access to the bus system. They require placing a terminal at one end, which starts a bus line. The user must manually place stops along the road, each with it's own sphere of influence. Bus stops do not require physical space on the map, but must make a complete circuit, ending back at the terminal. Double clicking on an earlier stop can have the game automatically plot out stops for the return trip on the original line. Buses will contribute to traffic amount as well, but if done well, will reduce the traffic of others.
Metros require first building the Metro Company, unlocked at 100,000 population, opening access to the system. It functions similarly to the bus in mechanics, needing terminals to start a line, but require physical stations with road access to be placed. Also a round circuit is not required, and each line cannot directly cross each other, instead passing between different levels. Lines can have conjoined stations, which provides citizens the ability to switch lines, essentially creating a web.