Mass Transit DLC

Solve gridlock by mastering the network connectivity, station placement, and route scheduling introduced in the Mass Transit DLC (released May 16, 2017) to support your city's growing population.

Cities: Skylines launched on March 10, 2015, as a single-player open-ended city-building simulation developed by Colossal Order and published by Paradox Interactive. While the base game allows players to manage zoning, taxation, and public services across a starting plot of land equivalent to a 2-by-2-kilometre area, the developers explicitly designed it with a focus on realistic traffic congestion. The core philosophy stems from Colossal Order's previous work on the Cities in Motion series, where they honed their expertise in designing effective transportation systems. This foundation allowed them to create an engine capable of simulating the daily routines of approximately 65,000 to 100,000 active agents at any given time, presenting complex traffic dynamics in a simple way for the player to understand and solve.

Quick Facts

Franchise: Cities: Skylines
Type: Expansion Pack; DLC
Primary focus: Public Transportation Systems

Lore & Background

Cities: Skylines does not feature an in-game narrative or plot; rather, its development history is rooted in the critical failure of the 2013 SimCity game. Paradox Interactive initially hesitated to greenlight a full-featured city simulation, fearing market dominance by existing franchises. However, after seeing the opportunity presented by SimCity's issues, they revised their approach with Colossal Order to focus on planning rather than political management.

The technical ambition of the project centers on creating a system where simulated citizens navigate roads and transit using dynamic pathfinding algorithms. Rather than adhering to rigid rules or being teleported when routes shift mid-transit, agents intelligently recalculate their paths in real-time to find the most efficient route. This design choice ensures that traffic jams accurately reflect the efficiency or failure of the player's road layout and geography, turning every intersection into a test of urban planning logic.

Reader's Guide

To manage traffic effectively, players must first acknowledge that road expansion alone cannot solve congestion. The guide begins with analyzing population density and job locations to identify where new transit lines are needed. Players utilize the robust transportation system inherited from Cities in Motion to place stations for metros, monorails, trams, buses, and ferries. Roads can be built straight or free-form, adapting zoning grids to their shape rather than forcing a square plan.

Variant road types, such as tree-lined avenues or highways with sound barriers, offer reduced noise pollution but at increased costs. Players must optimize bus routes to act as feeders from suburbs to major hubs and monitor passenger numbers to adjust schedules. The goal is to maintain the city in a sandbox mode for creative freedom or follow population tiers to unlock new improvements like waste management and health care, ensuring that tax revenue increases as buildings reach higher development levels driven by educated residents.

Did You Know?

The game engine simulates approximately 65,000 to 100,000 active agents simultaneously, though total population capacity can be higher depending on mods and hardware.
The base map grid actually consists of 81 tiles (9x9), though only a portion is available by default; Steam Workshop mods can unlock the entire area for massive city builds.
The Mass Transit DLC, released on May 16, 2017, expanded the transportation options to include Metro, Monorail, Tram, Ferry, and Bus Rapid Transit systems.