Bus Simulator 21: Best Engine.ini for City Traffic Optimization

The primary goal for Bus Simulator 21 traffic optimization is Asynchronous Asset Streaming. The game often hitches because it tries to load a high-detail bus model (LOD 0) and its unique traffic AI logic in the same frame. This configuration focuses on increasing the Texture Streaming Pool and forcing Background Level Streaming, allowing the city’s traffic to populate without dropping your FPS below 60.

File Path

The Engine.ini is located in your local AppData folder. Ensure you close the game and the bus simulator launcher before editing:

%LocalAppData%\BusSimulator21\Saved\Config\WindowsNoEditor\Engine.ini

Technical Configuration (The 2026 “Urban Flow” Template)

Open the file and paste the following block at the very bottom. These commands specifically target the Unreal Engine’s handling of distant AI and vehicle draw calls.

[SystemSettings]
# Bus Simulator 21 Traffic Optimization - GameEngineer.net
r.Streaming.PoolSize=3000          # Set to 50% of your VRAM
r.Streaming.LimitPoolSizeToVRAM=1
r.Streaming.DefragDynamicBounds=1
r.MaxAnisotropy=16
r.ViewDistanceScale=1.2
r.StaticMeshLODDistanceScale=1.2
r.ShadowQuality=3
r.Shadow.CSM.MaxCascades=2
r.Shadow.DistanceScale=0.8
r.AmbientOcclusionLevels=1
r.Streaming.Boost=2
r.AsyncPipelineCompilation=1

Parameter Breakdown:

• r.Streaming.PoolSize=3000: By default, BS21 uses a very small texture pool. Increasing this prevents the “blurry bus” bug where vehicle textures take several seconds to load when you pull into a station.
• r.Streaming.Boost=2: This forces the engine to prioritize loading the assets you are looking at. In a city environment, this ensures that the traffic ahead of your bus renders before you reach it.
• r.Shadow.DistanceScale=0.8: Reducing this slightly pulls in the shadow render distance. In heavy traffic, every car casts a shadow; shortening this distance significantly reduces the draw call count on the CPU.
• r.AsyncPipelineCompilation=1: A 2026-essential command that helps reduce “shader stutter” when turning corners into new city blocks.

Strategy for 2026 City Traffic Stability

• Traffic Density vs. FPS: In the in-game settings, setting Traffic Density to “High” is fine, but avoid “Ultra” if you are using many articulated buses. Each articulated bus has two “physics bodies,” doubling the CPU load per vehicle.
• Pedestrian Spawn Rate: If you experience “micro-stutters” near bus stops, lower the Pedestrian Density in-game to 70%. This reduces the pathfinding calculations without making the city feel empty.
• The “Mirrors” Performance Tax: In Bus Simulator, mirrors are essentially a second (or third) game window. Set Mirror Quality to Medium. This keeps the resolution high enough for safety but prevents the GPU from rendering the entire city traffic twice at full fidelity.
• NVIDIA Reflex / Low Latency Mode: Ensure this is ON. Bus driving requires precision braking; reducing the input lag between your pedal/button and the bus’s air brakes is vital for a “5-Star” rating.

Key Performance Parameters

Parameter	Recommended Value	Impact
View Distance	1.2 (High)	Keeps traffic visible without over-rendering.
Texture Pool	3000 – 4000	Fixes the “blurry dashboard” and bus liveries.
Shadow Cascades	2	Smooths out shadows on moving cars.
Anti-Aliasing	TAA / DLSS	Necessary for clean overhead wires and fences.

Frequently Asked Questions (FAQ)

Conclusion and Expected Results

By manually increasing the Streaming Pool and optimizing the Shadow Distance in your Engine.ini, you are removing the bottlenecks that plague Unreal Engine 4 city-builders. You can expect a significant reduction in “intersection stutter,” crisper vehicle textures during high-speed transit, and a more consistent frame pacing as you navigate through Angel Shores.