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FLEX Turn Lanes (FTL) and Related Projects - Development and Support

Started by Tarkus, August 01, 2009, 09:36:25 PM

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The FTL (FLEX Turn Lanes) system is a draggable and FLEX-based (pseudo-draggable) system for creating turn lanes and slip lanes for various road networks.  It was first prototyped by memo in January 2014, and is now the primary means of building turn lanes with the NAM as of the NAM Version 36 release. 

The now-deprecated predecessor of the FTL system was TuLEP, which stands for Turn Lane Extension Project(or Pieces). 

The initial idea behind this project came from two places: 1) an initial attempt at this sort of thing made by Chrno (the developer of the Avenue Wide-Radius Curves) with the existing NAM Avenue Turn Lane setup, 2) sheer necessity--I needed them to properly construct the SPUI Interchanges that were introduced in RealHighway Version 4.0.

TuLEPs Basic was first included as an option in the Network Addon Mod, beginning with NAM 28 (May 2010), officially labeled as the "Turn Lane Extension" in the NAM installer.  A TuLEP system for the 6-lane Avenue is also included in the Network Widening Mod (NWM).  The FTL system debuted in NAM 36 (September 2017).

An additional related project is SITAP--the Signalized Intersection and Turn Arrow Project, which uses a series of draggable overrides (and future FLEX pieces) to add signalized intersection support to the One-Way Road network, which lacked such support due to that network's hardcoded design features, in addition to turn arrows to the approaches.  The FTL system can also tie into SITAP intersections.

Post updated May 24, 2018

Both the new FTL system and the older TuLEPs are included in the main Network Addon Mod package, and are selectable as options in "Custom Installation".
None at the moment.

Optional Addons for the Old TuLEP System

NameAuthorRelease Date (M/D/Y) Description
TuLEP Cosmetic ModShadow Assassin05/16/2011Australian-style textures for TuLEPs, including dashed-line crosswalks and concrete dividers on Avenue TuLEPs.
TuLEPs Texture ModNego05/17/2011A North American-style texture mod which adds center crosshatching on TuLEPs transitions.
TuLEP ONLY Marking Cosmetic ModBlue Lightning05/20/2011Adds the word "ONLY" to the arrows on TuLEPs--now a full version including markings for Avenue TuLEPs.

The NAM Documentation features a detailed guide on using the FLEX Turn Lane (FTL) system and the Signalized Intersection and Turn Arrow Project (SITAP).  The guide can be seen online here, or can be found in the My Documents\SimCity 4\NAM Auxiliary Files\Documentation\feature-guides\turn-lanes folder after installing the NAM.

1. When is this getting released?
2. What networks are planned to receive TuLEP pieces?
3. How do TuLEP pieces work?
4. How many of these pieces are you guys going to make?
5.  How will the project be released?
6.  Are diagonals or curved turn lanes planned?
7.  Are FTLs and TuLEPs Left-Hand Drive (LHD) compatible?
8.  Will there be Right Turn Lanes?  Or Slip Lanes?
9.  Why are some of the pieces I've seen in this thread not included in the FTLs or Basic TuLEPs set?
10.  What is happening with Euro textures?
11. Will these turn lanes actually affect the functional capacity on my networks?
12.  Why are you using this approach rather than extending the original draggable Turn Lane functionality in the NAM?
13.  What about roundabouts?

1. When is this getting released?

The initial "basic" set of the original TuLEPs was been incorporated into the NAM as of the NAM 28 release of May 2010.  The new FTL system was introduced in NAM 36, released i September 2017.  The FTL system remains in active development, and is planned to receive expansions in future NAM releases.  The TuLEPs system, however, is now officially a legacy support item, and the once-planned "advanced" set of TuLEPs has been canceled. 

With regards to future turn lane content, like all other NAM Team projects, there is no release date or timeline for release.  (We tried the whole release date business once, with NAM 31--it didn't turn out too well.)

2. What networks are planned to receive TuLEP pieces?

Currently, the FTL system supports the following networks, with the types listed in parentheses.  Square brackets indicate override networks, and list the NAM component that contains them.

  • Road (Type 110)
  • TLA-3 [NWM] (Type 110)
  • AVE-2 [NWM] (Type 110)
  • ARD-3 [NWM] (Type 110)
  • Avenue (Types 120, 220
  • TLA-5 [NWM] (Types 120, 220)
  • TLA-7 [NWM] (Type 130)
  • AVE-6 [NWM] (Type 130)

Currently, TuLEPs only exist for the following networks:
-TLA-7 (in Network Widening Mod)
-AVE-6 (in Network Widening Mod)

Note: The Road and Avenue TuLEPs are designed in such a way that they can be used on the following networks in the Network Widening Mod:

The related OWR Signalization and Turn Arrow Project (SiTAP), also under this project umbrella, added lane control arrows to the base One-Way Road network in NAM 34.  All future turn lane content will be in the form of FLEX Turn Lanes (FTLs).

3. How do TuLEP pieces work?

The TuLEP puzzle pieces are part of a modular system that comprise different parts and configurations of turn lanes and lane control setups. These can then be assembled to create turn lanes of virtually any length.

Much like with the MIS Ramp Interfaces in the RHW mod, there will be different "Types" of TuLEP pieces (or "TuLEPs").  There will be several generic types that refer to the basic width/orientation of the turn lane setup on the network--i.e. Avenue Type 120, Avenue Type 220, etc.

The intersections for the TuLEPs are puzzle piece-based as well, and will be labeled such that you know which TuLEP pieces can be connected to it.  The intersections show "ghost arrows" as well, allowing for quick reference after you place the piece.  The pieces are intended to be functional rather than just strictly cosmetic, such that you can better control lane functionality in your cities.

Just place the TuLEPs over top of your existing networks and intersections.

The new FTL system is designed to use simple hybrid transition/starter pieces, which produce the base network out one side, and the turn lane setup out the other.  The turn lane overrides continue until reaching an intersection, at which point the intersection will override to match the turn lane setup.  The terminology for FTL setup types will be identical to that used for the existing TuLEPs.

4. How many of these things are you guys going to make?

Unknown at this point, but it can keep going for quite a long time.

5.  How will the project be released?

Both the FTL system and the deprecated TuLEPs Basic set currently exist as an optional plugins included in the NAM.  Contrary to popular misconception, TuLEPs Basic is not part of the NWM, though the TLA-7/AVE-6 TuLEPs are.

6.  Are diagonals or curved turn lanes planned?

Diagonals are planned for eventual inclusion.  Curved setups will be considered on a case-by-case basis.

7.  Are these turn lanes Left-Hand Drive (LHD) compatible?

Yes, they are.

8.  Will there be Right Turn Lanes?  Or Slip Lanes?

Yes and yes.  See Page 5 for the initial details.  Slip Lanes are included in the initial TuLEPs Basic set in the NAM, and now exist in draggable form with the FTLs.  Right Turn Lanes are planned for future development.

9.  Why are some of the pieces I've seen in this thread not included in the FTLs or Basic TuLEPs set?

These are prototypes for designs that at one point or another, were in development.  They may be brought back in some form in the future as part of the FTL efforts.

10. What is happening with Euro textures?

Both the FTL system and the TuLEPs have Euro texture options, which are installed as part of the NAM's Euro texture options. 

11. Will these turn lanes actually affect the functional capacity on my networks?

It depends on the configuration of the pieces and how they lay on the grid, but generally speaking, most will increase capacity of intersection approaches.  The setups are generally designed to as closely approximate the functional aspects of turn lanes (capacity and lane control) as feasibly possible within the constraints of SimCity 4 traffic simulation.

12. Why are you using a puzzle piece approach rather than expanding on the existing draggable Turn Lane functionality in the NAM?

Turning lanes, in real life, can vary greatly in length and lane control setups.  The system of network overrides used to implement the original draggable Turn Lane functionality for Roads and Avenues, while perhaps convenient, has limited control, requires an exhaustive and complex system of overrides and re-overrides in order to replicate just basic functionality of a fixed length (no more than 2 tiles) with considerable potential for instability, and can only be applied to intersections between two networks of the same type (Road/Road and Avenue/Avenue).  Additionally, the overrides and re-overrides entailed in the original draggable auto-turn lane plugins for Roads and Avenues created complications in developing the popular Network Widening Mod (NWM), which also later extended to the Draggable Elevated Road Viaducts and the Draggable Fractional Angle Roads.  "Workaround" systems were also tested, with limited success.

Given the options and limitations, a puzzle piece-based solution was originally deemed the most viable option to further turning lane functionality in the game.  However, as puzzle pieces have fallen out of favor as a viable implementation for most functionality in the current transit modding climate, and override technology has vastly improved, the these were swapped out for the draggable/FLEX-based system in the new FLEX Turn Lanes (FTL) system.  The FTL system does include a feature known as "QuickTurn", which will allow one-click placement of common intersection setups, with much greater variety than what existed in the old "auto" turn lane systems.

13. What about roundabouts?

There has been some talk of a TuLEP-style expansion for roundabouts, known as RABETs (Roundabout Extension Tiles).  However, aside from the large roundabouts added by MandelSoft in NAM 32, it hasn't progressed much beyond preliminary talk--there are presently no RABETs in active development, nor any plans to revive that project at present.

None at the moment.

Ramona Brie


This looks like it's going to be niiiiice...pretty! Can't wait to see it and RHW 4.0!



And a visual pun for a logo, no less.  Nice!   :D 

Overall, I think it's a great idea and a wonderful way to extend the versatility of the game even further.  :thumbsup:  And the only reason I say "overall" is that people are going to want me to make RTMT stations that fit all of these intersections...  ::)


Very, very nice! &apls

Will you be adding stop lights with turn arrows the? ;D


Not too shabby! Looks like another big project with some new possibilities! Now,if someone could make some working signals for some new lights! And its even more exciting since this can go hand in hand with the NWM!



Can't wait to see more of that project! Great work! &apls
Visit my MD, The region of Pirgos!
Last updated: 28 November


Fantastic stuff :o some awesome ideas you guys have :D

Copperminds and Cuddleswarms




Euro version is only needed for roads, since they have different textures here in Europe, and that means that they'll have to be incorporated in the Euro textures mod, which makes it Andreas' problem. Well, RHW-2 and 4 also need euro textures, making it the problem of the creators of those mods.

Question: Why are turning lanes needed for the RHW-4? They shouldn't have at-grade intersections, and there already exist puzzle pieces for the MIS-ramps.



Says who RHW-4 shouldn't have at grade intersections? How about one with a turning lane in the center, and you can cross the line of traffic to exit the road - you can't have a grade seperated interchange on every single country road, and it can save space. It's like a countryside avenue.

I don't understand fully the concept of the SPUI, but these pieces are needed for that puzzle piece also.
SimCity Aviation Group
I miss you, Adrian

Blue Lightning

Did someone say RHW4 turning lanes? Edit: Might as well stick the MIS one in too

And as Alex stated in his post, you can see that the top  3 segments can be reused (2+0+2 blank, 2+0+2 turn arrows, 2+0+2 x Ave (Left+Both+Right))

I still need to do some cleaning up (mainly with some blurring and seaming)


Though my main thoughts for RHW4 turnlanes is for limited access arterials, and at the terminus of one (thats why the TuLEP-MIS/RHW4 2+0+2  seen above is a T intersection)
Also known as Wahrheit

Occasionally lurks.

RHW Project

KoV Liberty

Oooooooooooh! Nice little project here Tarkus!

My new MD. Check it out if you wish.

Adrian, I miss you man.


Blue lightning, I suggest reducing the amount of turn-lanes on the MIS-version, to just two, one for each side.


Blue Lightning

Korot: Well a two lane version isn't under my coverage, but the reason I made it was for those "just in case" situations. (Edit 2: And now an example from a setup near me: here )  Also I plan on doing a MIS_TuLEP 1+0+1 to 2+0+2 transition. Though I do have a draft/unfinished 3 lane (1+1+1) texture right here:

Edit: Seems I forgot to crop it. Resized and added link.

Also known as Wahrheit

Occasionally lurks.

RHW Project


Ryan B.

Wow, this is great!  It also seems to be exactly what I've been designing signals for.

I think what I'm going to do is to make a vertically oriented signal set as well.  That way, everyone who isn't such a fan of the Texas-style horizontal signals I've done won't be left out.   :thumbsup:



Ah, it's for the SPUIs. I thought it was so the NWM could be released. Eh, 'scool anyway.


Well who says NWM networks won't be incorporated?  :P
NAM Team Member | 3RR Collaborater | Virgin Shores