Highway Interchange

The structural key to simulating a million citizens without gridlock.

In Cities: Skylines, the highway interchange serves as a critical junction where major roads cross without requiring stops. Developed by Colossal Order and published by Paradox Interactive in 2015, this infrastructure element is central to the game's single-player open-ended simulation. The developers specifically engineered the engine to simulate nearly a million unique citizens, with traffic congestion acting as a primary indicator of city design success or failure. These structures allow players to manage budget, employment, and pollution by ensuring smooth transit flow. Unlike previous titles that focused solely on transportation systems, this game integrates interchanges into a full-featured simulation where road layout dictates the growth and health of the entire metropolis.

Lore & Background

The focus on realistic traffic mechanics stems from Colossal Order's background with the Cities in Motion series. When pitching the city simulation concept, publisher Paradox Interactive initially hesitated due to the market dominance of SimCity. This changed only after the critical failure of the 2013 SimCity game provided an opportunity for a competing franchise. The team aimed to create a system where citizens navigate roads based on the fastest available route, taking into account transit systems and road density.

If a route is changed mid-transit, the simulated person is teleported back to their origin rather than recalculating from their current location. This logic ensures that visual traffic jams accurately reflect the efficiency of the player's design. The developers found that specific intersections, such as the single-point urban interchange or diverging diamond interchange, could be effectively modeled to demonstrate roadway efficiency.

Reader's Guide

To manage high-volume traffic flows, players must utilize the robust transportation system based on Colossal Order's previous work. Roads can be built straight or free-form, with the zoning grid adapting to the shape of adjacent roads rather than forcing a square plan. For major connections, players should employ variant road types like avenues with trees or highways with sound barriers to reduce noise pollution and increase property values. The game allows for various public transportation forms, including buses, taxis, trams, trains, ferries, and metro systems, which can be augmented along these routes.

If the standard 25-tile limit restricts a player's vision, they can use Steam Workshop modifications to open all 81 tiles (324 square kilometres) of the map. Additionally, pre-packaged mods like 'Unlock All' allow players to bypass population tier unlocks and access complex road networks immediately.

Frequently Asked Questions

Why are highway interchanges essential for city growth?

They act as the backbone of complex road networks, enabling the simulation to handle nearly a million citizens by preventing gridlock. Without them, congestion would quickly halt economic activity and city expansion.

How does using an interchange affect traffic management?

By removing stop-and-go signals, these structures significantly reduce travel times and lower pollution levels caused by idling cars. This efficiency directly improves the player's ability to manage budgets and employment zones.

Can players build custom interchange designs?

Yes, the game provides a variety of pre-built options and tools that allow users to construct unique layouts tailored to their specific terrain and traffic needs. These flexible designs are central to mastering open-ended city planning.

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