Before you run off in excitement to install the new NAM version, please make sure to read this (short) document first, to ensure the best Network Addon Mod experience. Note that without the 4GB Patch being properly installed, the game will crash to desktop.

REQUIREMENTS

• Java Runtime Environment (available from AdoptOpenJDK--a 64-bit Windows copy of JRE 11 is enclosed in the download)
  


• [For Windows Users]: NTCore 4GB Patch (included in download (4gb_patch.exe), or available from NTCore)
  


• 
  

Note that the NTCore 4GB Patch is REQUIRED, and due to the installer change, is no longer installed by default. The patch can be found inside the download, or downloaded directly from NTCore here, where further instructions on use of the patch can be found. Also due to this installer change, the NAM Controller Compiler is no longer run as part of the installation process. All users will be initially given a full NAM Controller, which has a substantial size. Users not using all features wishing to have a smaller controller can still run the Controller Compiler manually, as it is available in the download. Those on 32-bit versions of Windows should proceed with caution.

The NAM is also now using a Java-based installer, designed by daeley, which is cross-platform (meaning no more separate Mac versions, and Linux support without WINE). As such, the Java Runtime Environment (JRE) is now REQUIRED to run the NAM installer. It was previous recommended for users wishing to utilize the NAM Traffic Simulator Configuration Tool (TSCT). An open source version of Java can be downloaded from here.

Users who fundamentally object to installing Java (or are unable to for other reasons) can perform a manual install, with patience. Details can be found here

With the new installer, the old NAM installation is no longer removed automatically, so users should manually remove the "Network Addon Mod" and "z___NAM" folders from their Plugins directory. It is recommended, particularly with this Release Candidate, that you back those folders up in a location that is not in your Plugins folder. The "z___NAM" folder has been eliminated, and all files are now installed to the "Network Addon Mod" directory.

The RealRailway (RRW) standard for Rail is now the default and only option. One may choose to disable the RRW's more restrictive default slope settings by unselecting the "RRW Tunnel and Slope Parameters" box in the installer. The original Maxis Rail specification will be supported via a Legacy Plugin, downloaded separately, at a later date. Also note that a number of cosmetic-oriented NAM plugins, such as the El-Rail Alternate Implementation, the Bullet Train Mod, and some advanced texture options (largely deprecated) have been removed from the installer. The Alternate El-Rail and BTM will be made available separately at a later date. Please note that, much like Maxis Rail, these Plugins are effectively in "Legacy" status, and may not be actively maintained or supported by the NAM Team going forward. Both the original Maxis Highways (MHW) and the "Maxis Highway Override/Project Symphony" (MHO) remain available.

The Station Locator, Updater, and Reconstruction Project (SLURP) is also no longer handled by the new installer. A scaled down version of the old installer will be made at a later date to handle SLURP routines. Users wishing to retain SLURPed stations should retrieve them from the "z___NAM\Mass Transit Lots\Station Overrides" folder in their existing NAM installation, where they will be found in the "Mass Transit Lots" subfolder. Note that users running the 64-bit version of SimCity 4 on macOS may wish to refrain from retrieving SLURP stations, as there have been some encoding issues with stations that cause that version of the game to CTD.

The new installer also no longer performs a version check. Please note, however, that for Windows users, Version 1.1.638 and above are still required, as Versions 1.1.610 and 1.1.613 have notable instabilities that may have a significant negative impact on the use of this mod. Copies purchased from the Origin Store may still not meet this requirement, and support will not be offered to users with "unofficial" copies of the game.

• The L1 (Level 1, 7.5m height) Draggable Road, One-Way Road, and Avenue Viaducts can now form diagonal crossings with the following networks: Street, Road, One-Way Road, Avenue, Rail, Single-Track Rail (STR), Ground Light Rail (GLR), Elevated Light Rail, Monorail, L0 RHW-2, L0 RHW-3, L0 MIS, L0 RHW-4, L0 RHW-6S, L0 RHW-8S, L0 RHW-10S, L0 RHW-6C, L0 RHW-8C, and L1 MIS. Adjacency stability has been dramatically improved for all L1 Road, One-Way Road, and Avenue Viaduct crossings, and Diagonal FLEX Height Transitions have been added.
  


• Diagonal FLEX Height Transitions (FLEX-HT) for the RHW-2, MIS, and RHW-4 have been added (all L0-L1 only). Note that the RHW-2 version does not automatically produce L1 RHW-2 by dragging out the top--a change that has been extended to the Orthogonal FLEX-HT as well, to improve stability.
  


• The Hybrid Railway (HRW) FLEX Piece system has been added. Hybrid Railway tracks allow both Passenger Rail and Monorail/High Speed Rail traffic (designed for use with the future Real High Speed Rail (RHSR)), and also feature overhead catenaries. Stations, switches, and a base set of L1 Viaducts have been included. Ground HRW allows crossings with Road (OxO), L1 Road Viaduct (OxO and OxD), L1 One-Way Road Viaduct (OxO and OxD), and L1 Avenue Viaduct (OxO and OxD, click in Road stubs to fill in gaps on OxD). L1 HRW allows undercrossings with all ground-level Maxis, RHW, and NWM networks, plus L0 HRW (OxO only). To build these crossings, simply drag up to the edge of the HRW tracks, and once the crossing appears, resume dragging the network on the other side.
  


• Transitions between different Street sets in the Street Addon Mod (SAM) plugin are now possible, thanks to the addition of a new FLEX Transition piece.
  


• New Single-Tile Roundabout FLEX Piece added. The Single-Tile Roundabout allows for connections to Road and Street, and as the name indicates, takes up less room than the NAM's other Roundabout options.
  


• The Road Roundabouts have become more flexible, allowing double corner connections. Stability and pathng improvements have also been made.
  


• The diagonals for the Wider RHWs have received stability coding improvements. In addition, a capacity issue with the RHW-6C and RHW-8C diagonals has been addressed.
  


• The RHW Disconnector now covers all possible network combinations (including Non-RHW Combinations), allowing for more gentle bulldozing of any network setting.
  


• A multitude of pathing issues have been addressed, including a number of paths dating back to the original game, which had somehow escaped both Maxis and the NAM Team for the past 16 years.
  


• Some of the overridable Road Multi-Radius Curves (MRCs) added in NAM 37 have been migrated to new Instance IDs (IIDs) and may need to be rebuilt. This change is designed to better accomodate future expansion of One-Way Road Multi-Radius Curve and Fractional Angle capabilities.
  


• The GLR/Tram-in-Road and GLR/Tram-on-Street stations have been restored.
  

The Network Addon Mod will run on any system that meets the minimum system requirements for SimCity 4 Deluxe/Rush Hour. Most modern PCs should be able to comfortably run the mod, if running a 64-bit operating system. At least 1.2GB of hard drive space is required, in order to fully unpack the installer, but actual installation size may run from as little as 1.7MB to as much as 850MB, depending on the options chosen and if one selects to manually run the Controller Compiler after installation.

The Network Addon Mod is compatible with the following versions of the game:

• A) Retail Windows disc copies of SimCity 4 Deluxe OR SimCity 4 with the Rush Hour Expansion Pack, updated to at least Version 1.1.638.
  


• B) Retail Windows digital copies of SimCity 4 Deluxe OR SimCity 4 with the Rush Hour Expansion Pack (Version 1.1.641), from all digital retailers except Origin (i.e. GOG.com, Steam, Amazon).
  


• C) Digital Windows copies of SimCity 4 Deluxe obtained redeeming an existing CD key (not purchasing) through Origin Customer Support.
  


• D) Retail Mac digital copies of SimCity 4 Deluxe, purchased through Steam or the App Store. (NOTE: Platform-specific technical support for the NAM on macOS is extremely limited).
  


• E) Retail Mac disc copies of SimCity 4 Deluxe, running on macOS/OS X Version 10.6 (Snow Leopard) or earlier. (NOTE: Platform-specific technical support for the NAM on macOS is extremely limited.)
  

The Network Addon Mod is NOT compatible with the following versions of the game:

• F) Retail disc copies of SimCity 4 Deluxe OR SimCity 4 with the Rush Hour Expansion Pack that have not been patched (Version 1.1.610 or 1.1.613).
  


• G) Retail Windows digital copies of SimCity 4 Deluxe purchased from Origin.
  


• H) Retail disc copies of non-Deluxe SimCity 4 (sometimes marketed later as "SimCity 4 Classic"), without the Rush Hour Expansion Pack (Version 1.0.272 or earlier)
  


• I) Pirated or cracked copies of SimCity 4 Deluxe OR SimCity 4 with the Rush Hour Expansion Pack.
  

What should I do if the NAM installer rejects my copy of the game?

The new NAM installer (introduced with the NAM 37 Release Candidate) no longer runs a version check. However, it is strongly recommended that users check the version they are running, as unpatched copies can be unstable. In Case F, the solution is simply to install the EP1 Update 1 patch, which can be downloaded from EA (SKU 1-5), SimCity 4 Devotion (SKU 1-5), or Simtropolis (SKU 1 and 2 only). To determine the correct SKU version for your copy of SimCity 4, find the installation directory, and look in the subfolder named sku_data. Alternatively, one can simply try all the SKU versions of the patch, until one works.

For Case G, see the section about Origin below.

For Cases H, I, and J, it is recommended that you purchase a digital copy of SimCity 4 Deluxe (NOT from Origin).

What if my disc copy has simply stopped working with Windows Vista, 7, 8, 8.1, or 10?

Microsoft decided in 2015 that secdrv.sys, the driver file used by the SafeDisc and other disc copy protection systems present in many PC games from the early 2000s, was a security threat. As a result, the driver was not included as part of Windows 10, and Microsoft issued a Windows Update, KB3086255, which disables secdrv.sys on Windows Vista, 7, 8, and 8.1. In the case of the older versions of Windows, secdrv.sys can be re-enabled when needed through the use of the command prompt or a batch file.

Aside from the advanced step of manually signing a device driver for Windows 10, the only viable courses of action are to either purchase a retail digital copy of the game (NOT from Origin), or to redeem your CD key at no cost via Origin Customer Support (which, unlike purchasing from Origin, will result in you receiving a properly-patched version of SimCity 4 Deluxe).

Note that cracked executables (i.e. a "No CD" .exe) are not eligible for tech support. The NAM Team does not support piracy, but understands the frustration with the game's original DRM system being blocked by Microsoft, forcing one to buy a new digital copy in order to continue playing. However, the reason why cracked executables are not eligible is for more practical reasons, namely the potential for version mismatches (i.e. a Version 1.1.638 crack with Version 1.1.610/613 .DAT files, or vice-versa), which can greatly complicate the team's efforts to provide useful technical support to users. The Origin issues played a role in our keeping the version check in place, until the recent installer change in 2020.

Please note that if you are attempting to use an old, 32-bit version of Windows in order to still run your disc game, this will substantially hamper the performance of the game with the full NAM installed, and it is highly recommended that you run the game on a 64-bit operating system. If you must run on a 32-bit OS, you will most likely need to manually run the Controller Compiler and install a smaller feature set. (The RealHighway (RHW) system is by far the largest part of the NAM.)

Aside from a brief period in 2014-2015, Origin, the digital retail platform run by Electronic Arts (EA), has been selling defective copies of SimCity 4 Deluxe to retail customers. As of the release of NAM 38, this appears to still be the case. Unlike the retail versions sold by GOG.com, Steam, and Amazon (the "Thin Game Download" version), which come pre-patched to Version 1.1.641, the Origin retail copy is Version 1.1.610. By virtue of switching out the original SafeDisc copy protection for their own DRM, Origin altered the checksum of the game's executable, which prevents the EP1 Update 1 patcher--a piece of software they made--from running. This not only prevents the NAM from being installed, but leaves Origin retail copies with all the bugs that the developers fixed in 2003. It also prevents first-party content creation tools like the Building Architect Tool (BAT) from being installed. In effect, the Origin retail copy is unpatched and unpatchable.

The NAM Team recommends you contact Origin Customer Support about obtaining a refund, even after the return period has expired, as users have had success in this case. If you are among the users who are saddled with the unpatched and unpatchable Origin retail version, the team would also appreciate hearing from you, as we have a strong desire to see Origin give their customers a properly-patched copy of the game, and are trying to document just how many users are affected.

Strangely, copies obtained by redeeming an existing CD key at no cost with Origin Customer Support (Case C) are properly patched, despite what the same support team routinely tells those who bought copies and received defective Version 1.1.610 digital copies.

In short:

• Free copy from Origin Support for CD Key Redemption: Properly patched (1.1.641)
  


• Purchased copy from Origin Store/Origin Access: Unpatched and unpatchable (1.1.610)
  

For a more detailed assessment of the Origin situation, NAM developer Tarkus has written extensively on the subject at his blog, SimTarkus.

Aspyr recently issued an update to their port of SimCity 4 Deluxe for macOS, updating it from a 32-bit app to a 64-bit one on both Steam and the App Store, allowing it to be compatible with macOS Catalina (10.15) and later. This change has introduced a number of quirks, however.

Most notably, it has changed the key combination for cycling through TAB Loops under the NAM's various buttons. Instead of using TAB to move forward, and Shift-TAB to move in reverse, Mac users must now use Ctrl-TAB to move forward, and Ctrl-Shift-TAB to move in reverse. While TAB and Shift-TAB will allow one to move through the TAB Loop, these keys/combinations will cause some pieces under the buttons to be skipped.

Furthermore, the changes have also broken simmaster07's SC4MacInjector, which allowed DLL plugins--including SC4Fix.dll (which addressed the puzzle piece/TE Lot CTDs)--to run on macOS. As such, these fixes no longer work on Mac, and users should exercise caution when placing stations in the vicinity of static puzzle pieces.

Additionally, the installation procedure for the NAM varies depending on if one is using the Steam version or the App Store version.

With the Steam version, the NAM will install into the correct location by default: /Users/{username}/Documents/SimCity 4/Plugins/.

With the App Store version, after running the installer, move "Network Addon Mod" folder from the default install location to /Users/{username}/Library/Containers/com.aspyr.simcity4.appstore/Data/Documents/SimCity 4/Plugins/.

Instructions for All Users

When one initially opens the NAM package after downloading, there will be several items present, besides the document you are now reading: the installer itself is NetworkAddonMod_Setup_Version38.jar.

4gb_patch.exe is the NTCore 4GB Patch, the Controller Compiler folder contains the NAM Controller Compiler, the Documentation is loose in the folder (and in the "feature-guides", "images", and "old" folders-- this has not been substantially updated since NAM 36), and the Traffic Simulator Configuration Tool folder, which contains the Traffic Simulator Configuration Tool (TSCT).

NetworkAddonMod_Setup_Version38.jar is the NAM Installer, which you will need to run to install the NAM. If User Access Control (UAC) is enabled on your system, Windows may ask you to approve running the file with a simple "Yes"/"No" prompt. Click "Yes" to allow the installer to run.

In order to progress through the installer, simply click on each tab. Note that the license agreement must be agreed to before subsequent tabs can be accessed. The "Cleanup" tab allows one to remove any residual files from old NAM releases, and pre-NAM transit mods that might cause conflicts, and is loaded with the old Cleanitol list that shipped with NAM 36.

If you are upgrading from a previous version of the NAM, MANUALLY MOVE YOUR OLD NAM INSTALLATION OUT FROM YOUR PLUGINS FOLDER, INTO A SAFE LOCATION (note that this has changed from previous NAM releases). The NAM installer can no longer detect your previous installation options by reading the existing folder structure. It is recommended that you check your existing installation, to determine which features you presently have installed.

Generally speaking, the NAM Team makes every effort to ensure that new versions at least retain some form of "legacy support", such that cities built with any previous NAM version will continue to function well with the latest version.

If you have consolidated your NAM files using a tool such as SC4DatPacker or JDatPacker, please read the appropriate section.

The NAM Installer allows for many different types of installation--with the current NAM installation, custom installation is the only option, though the most common installation is set to be the default. Note that right-side driving (AKA RHD) and US textures are the default. A base Euro texture option remains available, and both the US and EU options are available for left-side driving (AKA LHD) as well.

While the NAM Installer, as noted above, has a series of checkboxes in Custom Installation relating to drive side, it is worth re-iterating that these boxes only change the compatibility files installed with the NAM, and do NOT change drive side. If you have an installation with Right-Hand Driving (RHD, vehicles driving on the right side of roads--this concept is NOT the same as the side one sits on when driving a vehicle) and wish to switch to Left-Hand Driving (LHD, vehicles driving on the left side of roads), this generally needs to be done either by adjusting the game's locale files, and then either editing the game's Windows registry entries, or by modifying the game's shortcut.

The new NAM Installer cannot determine default drive side of your installation, so make note of which side vehicles drive on in your game prior to installation. If you have changed your drive side by modifying the game's shortcut, instead of editing the Windows registry, then this would be the one and only case when changing the box checked here would be needed.

Due to changes in computer systems, and continued expansions of the NAM's main Controller file, in 2013, it was determined that many newer systems, particularly those with more than 4GB of RAM, and running 64-bit versions of Windows, need additional accommodation. To that end, the NAM includes a "4GB Patch", also known as a "Large Address Aware (LAA) Patch", which allows the game to access the full 4GB of RAM that a 32-bit application can read, instead of the default 2GB. The NAM's patch was designed by NTCore, and built into the NAM with permission, and users with systems that need the patch will receive a prompt during NAM installation to install it. The original patch can be found here.

The only thing this patch does is to switch the Large Address Aware switch, an accessible switch present in all Windows executables, from "off" to "on" for the game's executable. Patches like this are common in game modding communities, including those associated with Skyrim, Fallout, and Morrowind, and can be used to enhance any 32-bit application's performance on systems with 64-bit operating systems and a suitable amount of RAM.

The default directory for where SimCity 4.exe may be located depends on how and where you purchased your copy of the game.

• GOG.com: C:\GOG Games\SimCity 4 Deluxe Edition\Apps
  


• Steam: C:\Program Files (x86)\Steam\steamapps\common\SimCity 4 Deluxe\Apps
  


• Original Disc: C:\Program Files (x86)\Maxis\SimCity 4 Deluxe\Apps
  


• Origin*: C:\Program Files (x86)\Maxis\SimCity 4 Deluxe\Apps
  

*Note that only Origin copies acquired through Free CD Key Redemption (Version 1.1.641) are compatible with the NAM. Copies purchased through the Origin Store or accessed via Origin Access (Version 1.1.610) ARE NOT COMPATIBLE. See here for more details.

If you are an advanced user, and would like to trim down your installation of the NAM on the Mac platform, it is still possible to run the NAM Controller Compiler (a cross-platform application) after installing the NAM.

Extract/open the "Controller Compiler" folder, and double-click the file "NAMControllerCompiler.jar". Select the 'input' folder "Network Addon Mod/Controller/" from the current "Controller Compiler" directory, and the 'output' folder "~/Documents/SimCity 4/Plugins/Network Addon Mod/" inside your plugins. For the rest, follow the instructions of the compiler.

Programs to consolidate folders worth of SimCity 4 .DAT files, such as SC4DatPacker (Windows) and JDatPacker (cross-platform), are popular options known to improve game performance, given SimCity 4's preference to read a smaller number of larger files, instead of a larger number of small files--a fact determined by the BSC Team's "Miramba Experiment" of 2006. The use of "DatPacking" programs on one's NAM installation, however, is a controversial topic. The NAM Team's general advice is for Windows users to avoid DatPacking (unless one is extremely careful, while for Mac users, the use of JDatPacker is virtually required.

In general, if one plans to DatPack one's NAM installation, they should also save the pre-DatPacked NAM folder in a safe place, outside the Plugins folder beforehand. The reason for this is to avoid potential conflicts and issues, such as the "dual icon bug" and Controller file conflicts between new and old installations, as well as to make it such that one knows which options they have installed when upgrading to a new version, or re-installing the same version with different options.

In the case of the Aspyr port for the Mac platform (both App Store and Steam versions), it possesses a strange quirk in which exceeding a certain number of files or folders (regardless of size) in the Plugins folder can cause game slowdowns or even crashing-to-desktop (CTD). To this end, using JDatPacker after installing the NAM on a Mac is a necessity, in order to ensure proper game performance. Again, however, one should save their pre-DatPacked NAM installation in a safe place, outside the Plugins folder, to make for easy upgrades.

To uninstall the files, simply bulldoze every NAM item from this download in your cities and remove the files from the Plugins folder afterwards, which will be contained in Plugins\Network Addon Mod by default.

The NAM is a very expansive mod, with a substantial number of features, which may initially prove overwhelming to those not well-versed in its workings. The NAM Team anticipates that users, particularly those new to the NAM, may want to change the feature set they have installed, as they learn more about the mod's contents and capabilities.

To that end, we encourage users to keep the installer for the current version handy after initial installation. If you plan to change your particular set of options, you will need to remove your current installation. Moving it out of Plugins to a safe location is recommended, in case you want to keep your existing settings as a backup.

Users who are unable or unwilling to install Java can perform a manual installation of the NAM, something which the new file architecture introduced in 2020 makes far more possible than the previous "Monolithic" releases.

This method requires a file decompression tool capable of opening .jar files, such as 7-zip (Windows) or Keka (macOS). To begin, open NetworkAddonMod_Setup_Version38.jar using your file decompression tool.

The NAM's contents are located in the "installation" subfolder. The current installer uses a series of character flags at the start of directory names, in order to instruct the installer how to order the options, whether they're mandatory or optional, etc.

Numbers preceded by the dollar sign ("$"), i.e. "$1", "$2", etc., are merely being ordered with this flag.

Any directory with the caret ("^") in front of the name (or behind a "$" ordering flag) is mandatory.

Any directory with the exclamation mark ("!") in front of the name (or behind a "$" ordering flag) is not installed by default.

Any options where the equal sign ("=") and the dash ("-") are present are mutually exclusive--only one should be installed (the "=" option is the default).

The "$1^Core" directory is required. All other folders have options within them. With "4_Automata Controller#", "7_Texture and Drive Side Support", and "8_Traffic Simulator#", simply select one of the options inside and discard the rest, as these are straight up mutually exclusive one another.

The Automata Controller basically affects the display of the visual traffic in-game--Standard is going to be the lightest, while Radical is going to be the heaviest, Persistent makes the automata visuals last longer, and the 24-Hour modifiers handle whether the display is constant, or follows the data for the 24-Hour clock in-game.

The Texture and Drive Side Support includes four options, depending on whether you want to use US/North American textures or Euro/International Textures, and the drive side of your game (RHD or LHD, which should match your selection for the NAM Controller).

With the Traffic Simulator, these are ordered by the "$1" and the like in order of lowest capacity option to highest. Medium is the default.

With 5_DataView Options#, there's two subfolders. Both are just straight up options, with nothing mutually exclusive. You can probably just leave this one as is, unless you really don't like the Data View changes.

With 6_Miscellaneous, the two mutually exclusive options to watch out for are Extended Station Queries (there's four options in there--very subtle differences between them), and Maxis Transit Lots\Airport Capacity Adjustment#, which has three options (Default, Medium, and Large). And the Hole Diggers and Raisers are very much recommended--they have lots of use outside regular NAM usage, too.

With 3_Additional Transit Stations, this depends on if you want more transit stations beyond the game's default, and what the NAM adds by default for certain additional override networks. There should be no harm in either adding this one in whole, or leaving it out altogether, and if there's certain added stations you like/don't like, you can go in and customize this later.

2_Additional Network Features is by far the biggest area of the installer. This contains all the actual network feature addons in the mod. Most networks/network groups will have a "Base Features" folder, which really ought to be mandatory, as it contains a lot of the NAM's basic additions to each network, along with any Wide Radius/Multi Radius Curves and Fractional Angles, as well as Roundabout options for the various road-type networks.

The main "mutually exclusive" option to look out for here is with the Maxis Highways (there's two options--$1=Default Style, which keeps the Maxis Highways' default look and adds the NAM's additions for it, or $2-Maxis Highway Override (RHW-Style), which completely reskins the Maxis Highways, removes access to the default interchanges, and replaces them with RHW-style modular interchange functionality and a few new ploppable interchanges. Using the RealHighway (RHW) option is pretty much mandatory if you're going this route).

The other ones to watch out for are in Water Transport, where the Canal Addon Mod (CAN-AM) has two mutually-exclusive styles ($1=Callagrafx Style and $2-SimGoober Style), and there's also quite a few "non-default" options in Roads, One-Way Roads, and Avenues.

Those three non-default options are !Legacy Auto Avenue Turn Lanes (these are the old auto-turn lanes that appear on Avenue x Avenue intersections--largely considered "deprecated" now, as they can interfere with some newer functionality), !Legacy Semi-Auto Road Turn Lanes (the "semi-auto" replacement for the old auto-turn lanes on Road x Road intersections, which now appear by clicking over Road x Road + and T-intersections with the One-Way Road tool, also somewhat "deprecated" now), and !One-Way Road Arrow Plugins. These Arrow Plugins are mostly just a matter of taste, and, despite the folder naming, actually supposed to be mutually exclusive. "Elimination" gets rid of the arrows entirely, "Reduction" hides some of them (and actually impacts the base functionality of the OWR network to some degree), while "Single Arrows" replaces the default double arrows with just a single arrow (which looks nicer on the NWM networks).

The rest of 2_Additional Network Features is pretty self-explanatory, though micromanagement of these options is not recommended, since it is possible to produce a broken installation this way. RealRailway is the only/default option for Rail now, it's best to go all or nothing on RealHighways (RHW) and the Road, One-Way Road, and Avenue folder's "Additional Widths and Turn Lanes" option (which contains the Network Widening Mod and FLEX Turn Lanes).

If a feature has the word "Legacy" in the title, but it is not prefixed with "!", it is probably safest to install it, as it pertains to being able to keep certain older, deprecated content working, if you've built it with previous versions.