Ever watch your perfectly planned city grind to a halt with traffic jams that seem to come from nowhere? You’re not alone. The secret to smooth traffic flow in Cities: Skylines II isn’t just building more roads—it’s understanding how different types of roads work together in a hierarchical system.

Road hierarchy might sound technical, but it’s actually one of the most practical concepts you’ll learn for city building. Think of it as organizing your road network like a tree, with highways as the trunk, arterials as major branches, and local streets as the smaller twigs that reach every property.

What Makes Road Hierarchy Work

The beauty of road hierarchy lies in its simple principle: each road type serves a specific purpose. Higher-level roads prioritize speed and traffic flow, while lower-level roads focus on providing access to buildings and services. When you match the right road to the right job, traffic flows naturally.

You can think about it in terms of flow versus access. Highways have maximum flow but minimal access points. Local streets flip this completely—they provide direct access to every building but move traffic slowly. The magic happens when you connect these road types properly, creating a system where traffic naturally sorts itself onto the most appropriate route.

The Four Essential Road Types

Highways: Your City’s Backbone

Highways serve as the main arteries connecting your city to the outside world and moving large volumes of traffic quickly across long distances. These roads should have the fewest possible connections to maintain their speed advantage.

Keep highway connections limited to on/off ramps and avoid placing intersections directly on highway segments. Direct property access on highways creates bottlenecks that defeat their purpose. Save highways for through traffic and long-distance movement between major city districts.

Arterial Roads: District Connectors

Arterials form the primary network within your city, connecting highways to major districts and facilitating cross-city travel. These roads handle substantial traffic volumes while providing controlled access to important areas.

Limit intersections on arterials to prevent stop-and-go traffic patterns. While some zoning on arterials can work, avoid placing high-traffic generators like large commercial areas directly on these roads. Think of arterials as express routes through your city rather than neighborhood streets.

Collector Roads: Traffic Gatherers

Collectors serve as the crucial middle layer, gathering traffic from local streets and feeding it efficiently onto arterials. They allow for more intersections than arterials while still maintaining reasonable traffic flow.

These roads work well for moderate zoning, including smaller commercial areas and medium-density residential zones. The key is balancing accessibility with flow—collectors should connect easily to local streets while providing clear paths to arterials.

Local Streets: Property Access

Local streets form the foundation of your road network, providing direct access to homes, businesses, and services. These roads prioritize accessibility over speed, with frequent intersections and connections.

Design local streets for low-volume traffic moving at residential speeds. Every building should connect to the road network through local streets, which then feed into collectors rather than jumping directly to arterials or highways.

Here’s the video that inspired my latest city design – it’s worth watching to see these concepts in action.

Building Your Hierarchy Step by Step

Start with your highway connections, which Cities: Skylines II provides in most maps. These external connections represent your city’s link to the broader region and should guide your arterial placement.

Connect major arterials directly to highway interchanges, creating the primary routes that will carry most of your cross-city traffic. Space these arterials appropriately—too close together and they compete for the same traffic, too far apart and local streets become overloaded.

Build your collector network next, connecting arterials to the areas where you plan neighborhoods and commercial districts. Think about how traffic will naturally want to flow and provide logical routes that match those patterns.

Fill in with local streets last, creating fine-grained access to individual properties while ensuring these streets connect to collectors rather than directly to arterials. This prevents local traffic from clogging your higher-level roads.

Traffic Solutions That Actually Work

Smart Intersection Management

Use traffic lights strategically on arterials and collectors, but consider roundabouts for intersections that see steady traffic from multiple directions. Roundabouts often handle moderate traffic volumes more efficiently than stop signs or traffic lights.

For highways, avoid intersections entirely. Use bridges, tunnels, or on/off ramps to maintain uninterrupted flow. Even a single traffic light on a highway can create ripple effects that impact your entire network.

Strategic Spacing

Space your intersections based on road type. Highways should have minimal connections spaced far apart. Arterials can handle intersections every few blocks, while collectors and local streets can connect more frequently.

The goal is preventing higher-level roads from being overwhelmed by local traffic decisions. When someone needs to drive across town, they should naturally choose the arterial rather than cutting through residential streets.

Future-Proofing Your Network

Plan for growth by leaving space to upgrade roads as your city expands. A collector road that works perfectly for a small neighborhood might need to become an arterial as surrounding areas develop.

Consider how your road hierarchy will evolve. That initial arterial connecting your first districts might eventually become a local route when you build a proper highway bypass around your growing city center.

Common Mistakes to Avoid

Don’t connect every road to everything. One of the biggest hierarchy mistakes is creating too many connections between different road levels. Local streets shouldn’t connect directly to highways, and residential areas shouldn’t dump directly onto major arterials.

Avoid the temptation to solve traffic problems by simply adding more lanes. If traffic is backing up, the issue is often poor hierarchy rather than insufficient capacity. Sometimes the solution is removing connections rather than adding them.

Watch out for unintended shortcuts. Citizens will always choose the fastest route, even if it means cutting through residential areas. Use your road hierarchy to guide traffic onto appropriate routes rather than fighting against natural traffic patterns.

Putting Theory into Practice

The next time you start a new city, begin with the hierarchy in mind. Instead of building roads as you need them, plan your arterial network first, then work down to collectors and local streets.

As you zone new areas, ask yourself: how will traffic from this district reach the highway? The answer should involve a clear path from local streets to collectors to arterials to highways, with each step handling the traffic appropriately.

Remember that road hierarchy works with other city systems too. Place bus stops and subway stations along arterials and collectors rather than forcing transit onto local streets. Design pedestrian paths to reconnect neighborhoods that arterials might divide.

Building Cities That Flow

Mastering road hierarchy transforms your approach to city building in Cities: Skylines II. Instead of reactive traffic management, you’ll build proactive networks that handle growth naturally. Your citizens will spend less time stuck in traffic and more time enjoying the city you’ve created.

The concepts might take a game or two to fully internalize, but once you start thinking hierarchically, you’ll never go back to random road building. Every new street will have a purpose, every connection will serve the broader network, and your cities will flow as smoothly as you always imagined they could.

Want to explore more advanced city building techniques? Check out our guide to starting your first city in Cities: Skylines II for comprehensive planning strategies, or dive into our progression system breakdown to understand how city growth affects your infrastructure needs.

For broader strategy gaming insights, our turn-based vs real-time strategy comparison explores different approaches to planning and execution that apply beyond city builders.