Do you want to prevent players from entering the Metro Tunnel System, then this is the right map for you.
After simply add the name of this resource to your server.cfg
resource section.
altv-os-map-BlockedMetroTunnelSystem
Then simply clone this repository into your main server resources folder.
cd resources
git clone https://github.com/ThomasMarangoni/altv-os-map-BlockedMetroTunnelSystem
You can find an Imgur Album with multiple pictures here: https://imgur.com/gallery/TZlTH60