Traffic congestion is one of the biggest challenges in City Skylines II, and poorly designed junctions are often the root cause. This guide will walk you through various techniques—both vanilla and modded—that can help improve traffic flow and efficiency in your city. Whether you’re playing without mods or using Traffic Manager and DLCs, these methods will help optimize your road networks.

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Understanding the Problem: Why Do Junctions Get Congested?

Junctions become clogged due to multiple factors, including inefficient road layouts, lack of dedicated lanes, and poor traffic control. Key issues include:

• Multi-purpose lanes causing conflicts between vehicles.
• Lack of dedicated turning lanes, forcing vehicles to wait unnecessarily.
• Traffic lights without optimization, leading to delays.
• Poor pedestrian infrastructure, making roads the primary travel option.

By addressing these factors, we can create smoother junctions with better traffic flow.

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1. Adding Traffic Lights (Vanilla Fix)

The simplest fix is to add traffic lights. This ensures that all directions get a fair chance to move. However, default traffic lights may not be the most efficient option.

How to apply:

• Select the junction and enable traffic lights using the in-game road tools.
• Monitor traffic and adjust road layout if needed.

While this can improve movement slightly, it may not be sufficient for high-traffic areas.

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2. Using Asymmetrical Roads for Better Flow

If you have the Mass Transit DLC, asymmetrical roads (3-lane, 2+1 configurations) are an excellent upgrade.

Benefits of Asymmetrical Roads:

• Dedicated turning lanes prevent congestion.
• More efficient lane usage, reducing bottlenecks.
• Smooth traffic transitions at junctions.

How to apply:

• Replace two-lane roads with asymmetrical 3-lane roads (2+1).
• Ensure the wider section faces the incoming traffic.
• Monitor vehicle flow and tweak lanes accordingly.

If you don’t have the DLC, consider using larger roads with multiple lanes to improve movement.

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3. Expanding to 5-Lane Roads (Network Extensions 2 Mod)

For players using the Network Extensions 2 mod, the 5-lane road (3+2 configuration) can further improve traffic flow.

How to apply:

• Upgrade roads feeding into junctions with a 3+2 layout.
• Ensure turning lanes are separate from straight-ahead lanes.
• Observe lane usage and adjust if necessary.

This setup allows for multiple movements simultaneously, reducing congestion significantly.

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4. Lane Arrows for Precise Control (Traffic Manager: PE Mod)

Using the Traffic Manager: President Edition (TM:PE) mod allows for lane-specific traffic control.

How to apply:

1. Open TM:PE and select Lane Arrows.
2. Ctrl + Click on the junction to auto-assign dedicated turning lanes.
3. Manually adjust lanes if needed to optimize movement.

This method ensures that every lane has a clear function, reducing unnecessary weaving and slowdowns.

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5. Implementing Timed Traffic Lights (TM:PE Advanced Feature)

For better control of signal timings, Timed Traffic Lights can make a huge difference.

How to apply:

1. Open TM:PE and select Timed Traffic Lights.
2. Click the junction and choose Ctrl + Click for an automatic setup.
3. Adjust signal timings manually for peak-hour traffic balancing.

Timed traffic lights prioritize heavy traffic flows and optimize movement through junctions dynamically.

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6. Replacing the Junction with a Roundabout

In many cases, roundabouts provide a superior alternative to standard intersections.

How to apply:

1. Use the Roundabout Builder mod or construct one manually.
2. Set up give-way (yield) signs using TM:PE.
3. Ensure proper lane allocation for smoother transitions.
4. Provide pedestrian crossings away from the roundabout.

Best Practices for Roundabouts:

• Use 3-lane roads for larger roundabouts.
• Ensure incoming roads have equal or fewer lanes than the roundabout.
• Implement asymmetrical feeder roads for optimal efficiency.

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7. Bypass Lanes to Reduce Junction Load

Not all vehicles need to pass through an intersection—many just need to go straight. Creating bypass lanes can divert unnecessary traffic.

How to apply:

1. Construct a parallel elevated road for through traffic.
2. Ensure only selected vehicles use the bypass via lane management.
3. Adjust speed limits to encourage bypass usage over intersection waiting.

This method drastically reduces congestion at key junctions.

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8. Managing Lane Mathematics

Lane Mathematics refers to ensuring that roads smoothly transition based on their lanes.

Basic Rule:

• If a 3-lane road splits into an exit, the main road should downgrade to 2 lanes (3-1=2).
• If a 2-lane road receives merging traffic, it should upgrade to 3 lanes.

How to apply:

1. Use asymmetrical roads to control lane numbers at junctions.
2. Use TM:PE’s Lane Connector tool to fine-tune traffic behavior.

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Final Results & Performance Metrics

After implementing these fixes, you should see a noticeable improvement in traffic flow. Cities plagued with junction congestion can often go from 30% traffic flow to 75% or higher by applying these methods systematically.

Before & After Comparison:

Scenario	Traffic Flow (%) Before	Traffic Flow (%) After
Default intersection	30%	40-50%
Asymmetrical roads	30%	50-60%
Dedicated lanes (TM:PE)	30%	60-70%
Timed Traffic Lights	30%	70-75%
Roundabout Implementation	30%	75-80%

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Conclusion: The Best Approach for Your City

The ideal solution depends on your city size, mod availability, and road hierarchy. Vanilla players can benefit from simple fixes like asymmetrical roads and bypass lanes, while modded players can achieve near-perfect traffic flow with lane connectors, priority signs, and advanced AI adjustments.

By systematically diagnosing and fixing traffic issues, you can create a thriving, efficient city without endless congestion. Have more ideas? Drop them in the comments below!