Bus Simulator 21: Best Engine.ini for City Traffic Density Fix

The objective of this configuration is to increase the efficiency of the Background Task Manager and stabilize the Level of Detail (LOD) transitions for distant traffic.

File Path & Access

File Path: %LOCALAPPDATA%\BusSimulator21\Saved\Config\WindowsNoEditor\

Step-by-Step Instructions:

1. Press Win + R on your keyboard, paste the path above, and press Enter.
2. Locate the file named Engine.ini. (Always create a backup named Engine_Backup.ini before editing).
3. Right-click the file and select Open With > Notepad.
4. Scroll to the very bottom of the text and paste the configuration block provided below.
5. Save the file and restart the game.

Optimized “Urban Traffic” Configuration Block

[/Script/Engine.RendererSettings]
r.Streaming.PoolSize=4096
r.Streaming.LimitPoolSizeToVRAM=1
r.Shadow.DistanceScale=1.5
r.ViewDistanceScale=1.2

[SystemSettings]
r.SceneColorFringeQuality=0
r.MaxAnisotropy=16
r.Tonemapper.Sharpen=0.5
net.MaxRPCPerFrame=100
gc.TimeBetweenPurgingPendingKillObjects=120

Parameter Details & Technical Purpose

Parameter	Recommended Value	Technical Purpose
r.Streaming.PoolSize	4096	Allocates more VRAM for textures, preventing hitches when turning corners into new city blocks.
gc.TimeBetweenPurgingPendingKillObjects	120	Extends the Garbage Collection interval, preventing the “Physics Pause” every few minutes.
r.Shadow.DistanceScale	1.5	Balances shadow quality for distant traffic to reduce Draw Call overhead.
net.MaxRPCPerFrame	100	Optimizes the communication between the AI logic and the renderer for smoother movement.
r.SceneColorFringeQuality	0	Disables Chromatic Aberration for a much cleaner, sharper image in urban environments.

Best Practices for 2026 Urban Simulation Stability

To ensure your bus routes remain smooth during peak traffic hours, follow these additional GameEngineer.net technical steps:

• The “Pedestrian” Cap: While the Engine.ini helps with the technical load, if you are still hitting CPU limits, set the in-game “Pedestrian Density” to 70-80%. In 2026, the 100% setting is designed for extreme multi-core processors (16+ threads).
• DirectX 12 Toggle: Bus Simulator 21 performs significantly better under DirectX 12 for draw call management. If you experience crashes, ensure your Windows 11 “Graphics Settings” has Hardware-Accelerated GPU Scheduling (HAGS) turned ON.
• SSD Asset Streaming: Because UE4 streams city assets based on your bus’s speed, an NVMe SSD is mandatory. If you experience “floating cars” or “gray buildings,” the game is failing to pull data through the I/O pipeline fast enough.
• Controller Latency: If you use a racing wheel (Logitech/Thrustmaster/Fanatec), ensure your polling rate is set to 500Hz or lower. High polling rates (1000Hz+) can interfere with the UE4 main thread in this specific title, causing micro-stutters during turns.