Updated: February 2020
Traffic defaults to driving on the right.

When you are creating a new game (the screen where you choose map or scenario), there's a small option under the map image that lets you switch to driving on the left.


If you want to change traffic direction for an existing city, it's a bit more complex - follow the next 3 sections of this guide...

Updated: April 2020
Subscribe and enable these mods:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=667342976
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1777173984
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=450877484
Note: You might need to exit game to desktop and relaunch the game to get ModTools working properly.

Updated: April 2020

Important:

If you use Traffic Manager: President Edition to customise your roads, all of those customisations will freak out when you change the road direction in-game. Make sure you remove any lane connections before changing direction, and check everything over after the direction is changed

Follow these steps:

1. Load your city
   
2. Leave the game paused during this process
   
3. Open the scene explorer (Ctrl+E) in Mod Tools
   
4. Find "SimulationManager"
   
5. Look for "m_metaData" and set the "m_invertTraffic" field to:
   
   • 'true' for driving on the left (LHT / RHD)
     
   • 'false' for driving on the right (RHT / LHD)
6. Save the game (under new file name)
   
7. Exit to desktop

Updated: February 2020
A sudden change in traffic direction confuses the game - a lot! So we need to clear up the mess.

Follow these steps:

1. Relaunch the game, and go to the main menu ("Play" option from the Paradox Launcher app)
   
2. Choose: Content Manager > Mods
   
3. Find "Loading Screen Mod" and click the "Options" button
   
4. Enable all "Safe Mode" options (this will clear down all traffic, solving most of the problems)
   
5. Now re-load your save
   
6. Leave the game paused during this process
   
7. Press Ctrl+Zero to open the Broken Nodes Detector tool
   
8. Use each of the fetures on it to clear up any broken stuff
   
9. Save the game (under new file name)
   
10. Exit to desktop
    
11. Relaunch the game and load your city

If it worked, your city should now be driving on the other side of the road!

Note: You can now remove the mods as they are no longer needed, although I'd suggest keeping Loading Screen Mod as it massively reduces RAM consumption and makes loading much faster.

You might need to check over any remaining transport lines (bus routes, etc) to check if they are working as expected; if they aren't just delete the lines and create new ones.

If you can think of other useful things to add to this guide, or have any comments, let me know in the comments below.

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