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Cloverleaf and Cloverfold Interchanges

Started by Haljackey, November 26, 2011, 01:08:53 PM

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Section 4:  Cloverleaf and Cloverfold Interchanges

Cloverleaf interchanges are the arguably the easiest way to connect two RHWs with one-another. The use of four loop ramps as shown above resemble that of a four leaf clover, thus the name cloverleaf.

The cloverleaf section will be short because we can already make them with the Maxis Highways, and the fact that their design can cause weaving, something I don't like.  Additionally, they take up a monstrous amount of land using the RHW, even when you are going for a compact design.

4.1 Simple Cloverleaf Interchange
4.2 Complex Cloverleaf Interchange (with collector/distributor roads)
4.3 Partially Unraveled Cloverleaf Interchange
4.4 Simple Elongated Cloverleaf Interchange

Back to the Table of Contents


Section 4.1: Simple Cloverleaf Interchange (Created by Haljackey)

The simple interchange I am going to show you resembles some of the older, outdated freeway designs, minus the weaving lanes.

Drag out your RHW.  For this example I am using a RHW-4 with a 0 tile median.

Create your overpass.  Plop your RHW-4 to El-RHW-4 transitions right next to the underpassing highway.  Drag out your RHW from the overpass.
-You might want to make your overpass a bit longer if you are to widen your RHW or make weaving lanes in the future.

Plop 8 RHW style "B" ramps at the edge of the under/overpass.  Make sure they all face outwards.
-This example is the most compact design.

Then use the MIS to connect them up to form the inner loops. 
-This is the most compact form.

To give a more realistic appearance, try to elongate your loop ramps to make them more circular.

To make the junction more uniform, you can also move your style "B" ramps on the underpassing RHW further away from the underpass so it lines up with the overpassing RHW's ramps.

...And you can also elongate the ramps here as well. 
-I'm going to continue the guide with this example because it has the most circular loop ramps.

Drag four diagonal segments of RHW-2 right next to your loop ramps like so.  This will serve as a guideline as to where to plop your outer ramps.

Plop 8 more RHW style "B" ramps where the RHW-2 segments meet the RHW-4.  Part of the RHW-2 should now change into MIS.  Redraw your RHW-2 with the RHW tool and it should convert to MIS.

There you have it, a fully functional simple cloverleaf interchange!  Talk about a space hog eh?
-In fact, this junction is so large that the Maxis highway cloverleaf interchange nearly fits inside one of the loop ramps.  How's that for a size comparison?   :P

This also marks the first 4-way RHW-RHW tutorial in this guide! &dance I hope you found it helpful!


Section 4.2:  Complex Cloverleaf Interchange (Created by Haljackey)

Here I`ll be showing you how to make a more realistic, higher capacity cloverleaf interchange compared to the simple cloverleaf shown in section 4.1.  It shares many similarities with the junction Blue lightening (Vince) posted but has some distinct differences.

This page is getting flooded with images, so I have been making my images smaller to help minimize clutter and loading times.  Hopefully you can still clearly see what`s happening despite the size reduction.

To keep consistent with section 4.1, I will be using a RHW-4 with a 0 tile median for the main routes.

Note: Hole digging lots are required for this guide, and using a slope mod is strongly suggested.

Drag your RHW.

Plop some ground lifters on either side of the RHW, at least two tiles away.

Drag road from the ground lifters away from the RHW to create a slope.

Demolish the ground lifters and roads.  Use road stubs to even everything out.
-You`ll want a 4x1 segment of ground lifted, like so.  The road stubs are on the raised terrain.

Now drag your second RHW.  Create not only one on-slope overpass for the main route, but secondary overpasses as well.
-You`ll want a slope mod to create a smooth grade.

Plop 4 RHW-4/MIS splitters next to the adjacent overpasses.  There should be about 4 tiles between this junction and the underpassing RHW.

Complete your bridges. Drag RHW from one side to the other for all 4 overpasses.  Check to make sure the RHWs are facing the correct direction.  Drag MIS from the RHW-4/MIS splitters parallel to the RHW.
-Notice the weave lane?  This is an iconic part of cloverleaf interchanges. &blush Its also the reason designers hate it.  At least here we have the weave lanes separated from the main highway :P

Now its time to plop 4 RHW-4/MIS splitters next to the underpassing RHW.  They should be 3 tiles away from the overpass to keep the junction symmetrical.

Drag your new RHW and MIS segments parallel to the main route.  Check to make sure the RHWs are facing the correct direction under the overpass.
-See how this thing is starting to come together?  ;)

Carefully construct your loop ramps.  For best slope results, drag from the overpassing RHW's junctions.
-Depending on how restrictive your slope mod is, the size of your loop ramps may differ.  My loops may not be as circular as yours because I use a very restrictive slope mod.

Now its time to construct your outer ramps like so.  Drag from your MIS parallel to your RHWs as close to the loop ramps as possible, without draging over graded tiles.  (This will impact the slope of the loop ramps and your outer ramps will not be flat.)

Do that for all 4 sides.  When you're done that your junction should look something like this:
-We're almost there!  It's huge, isn't it?  $%Grinno$%

We need to connect those parallel MIS ramps with the main RHW now.  Select the RHW-4 type "C" ramp and plop 2 of them in each quadrant.
-Don't worry about the RHW glitches for now, it will be fixed in the next step.

Plop your RHW-6S to RHW-4 transition a few tiles away from the junctions.  I recommend at least 7 tiles for realism.  Use the RHW tool to redraw any glitched sections now, as they should revert back to RHW-4.
-The road stubs are here show 7 tiles.

...And you're done!  Here's the finished interchange.  What a beast!

Additional Images

You can also plop some RHW-4/MIS splitters where the two MIS sections meet.  This may look nice, but it isn't really needed because these ramps are already separated from the main highway and will make your junction even larger.

Shown here are two additional ways you can hook up your ramps to the main RHW. 
-The RHW heading east merges into one lane before merging onto the main RHW.
-The RHW heading west has separate lanes for each exit before breaking off the main RHW.
-The road stubs are here to show 7 tiles of merge space.

And there you have it, a complex cloverleaf interchange complete with weaving lanes! 

This design is slightly safer than typical cloverleaves because the weaving is taking place away from the main route.  However this design is more costly and takes up more space. 
-Nowadays cloverleaves are hardly ever built because of the danger weaving presents to drivers.  However in SC4, weaving doesn't make a difference to traffic capacity or speed, so its ok to use.  Still, I would suggest a design that doesn't contain any weaving that I may present later in future guides.


Section 4.3 Partially Unraveled Cloverleaf Interchange or Partial Cloverfold (Created by jdenm8)

This is a SC4-tailored design I built from a need to have a weave-less Half Cloverleaf, and I pretty much just applied the idea to a standard cloverleaf. The main traits are that weaving is eliminated on the lower highway, and it's significantly more compact than a standard SC4 cloverleaf (We're using FlexFly, it tends to do that).
However, the upper deck still has basic cloverleaf designs intact, so weaving isn't completely eliminated. We have to wait for HEMIS for that  &mmm
Now, this interchange, due to the density of puzzle-pieces, means that if you stuff up even once you may have to demolish the entire interchange and start over.

To my knowledge, no interchanges of this type exist in RL.

This interchange requires RHW 4.1!

Anyway, how to build it.

First, take your crossing motorways. As you know, you will have to use RHW-4 for the overpass, but any RHW should work underneath.

Measure out two tiles on both sides (we're leaving space for the ramps) and then place the ERHW-4 Type A offramp so the ERHW-4 starter stub sits beside the second measured tile, like in the below picture.

Next, we plop the RHW-4 to ERHW-4 transitions so that the ERHW-4 starters sit over the ERHW-4 starters of the Type-A exits.
Then we build the first looping ramps as shown below. (These can be on the same sides of the intersection if you want, I like it double mirrored) I dragged out seven tiles for deceleration for the loops.
Drag the MIS one tile past the overpass, then plop a starterless ON (for LHD) or OFF (for RHD) MIS to EMIS transition on the single tile stub.
Don't worry about the upper level, we don't need a starter stub there.

Now, we plop our A2 FlexFly loops (The one with the yellow line on the outside). This is why we don't need a starter stub on the upper level. Plop as shown in the pic, then drag MIS from the FlexFly ramps to connect them.

Your intersection should now look like this.

Next, we construct the other loop ramps. They're much the same, except they don't have a two-tile gap like the first ones, these have a one tile gap.
At the same time, build the MIS ramps on the ground level. These thread through the FlexFly on the tile beside the MIS to EMIS transition. Again, drag only one tile beyond the overpass. To connect to the motorway, you can use FAMIS or the Wide A-Type ramp for RHW-4. If you're not using RHW-4 underneath, the DRI Type-B ramp can sometimes work, but it's temperamental.

WARNING! The ERHW-4 likes to deconvert to RHW-2 at this point if you're dragging RHW-2 underneath to start with. Once you drag MIS through the new offramp, the overpass will pull itself back to ERHW-4. Until you drag MIS through, the overpass will not convert back to ERHW-4, so don't bother clicking all over the place.

Next, we plop the other type of starterless MIS to EMIS transitions, (OFF for LHD, ON for RHD) between the FlexFly piece and MIS on the new ramps.

Now, we've done the Looping ramps, the hard part, but now we need to connect the other four routes.
You can use FAMIS for this, but I used DRI Type-B ramps to save time.

Because we used FlexFly for the loops, you can be creative with the connections. By making the loops a tile wider, you can even fit the wide MIS curve puzzle piece in there!

Hope this helps guys. It's an unusual and slightly overweight bunny, but it looks very good when done and half of the weaving of a regular Cloverleaf is gone.


Section 4.4: Simple Elongated Cloverleaf Interchange. (Created by apeguy)

Okay, this tutorial will be showing you how to build a somewhat unique kind of cloverleaf interchange, and probably the biggest type out of the examples shown here, as you can fit an entire maxis cloverleaf inside one of the leaves. Although this junction, like all clovers, is free-flowing and is full access from all directions, this is relatively low-capacity due to the unique design of the slip roads. So this would probably suit a rural area, where two low-capacity highways meet and need full access in all directions, and space isn't an issue.

So, let's build this thing. Start off by dragging two highways across each other. I've used RHW-4 because it's the easiest to work with. In this example I have use EL-RHW4 for the overpass because you can build the slip lanes closer together than if you used hole digging lots to create a smooth, gentle slope. Although it's less realistic, this time we're going for simplicity.

The next step is to build 8 RHW4 style B ramps, as shown in the image below. It is best to build them all the same distance from where the two highways cross, in this case, 10 tiles.

Next you need to extend the MIS ramps out from the ramps. Make sure that you extend all the ramps out the same distance. Here you can see that I have dragged the MIS until there is four tiles between it and the highway. This is the bare minimum. You will see why later on.

Next, place an RHW2 Splitter style A at the end of every MIS ramp, With the RHW2 end at a right angle to the main highway. Next drag the other part of the splitter ramp up to the highway and then turn 90 degrees. Now you can see why you had to extend the diagonal MIS out at least four tiles from the highway. This makes sure that there is enough room for the other MIS to make that 90-degree turn. Any smaller and it wouldn't create that smooth 90-degree turn.

This should be your finished result. Now you can see its design is starting to differ from that of a standard cloverleaf.

Next you just need to add some RHW4 style A ramps to connect the remaining MIS ramps up. You're nearly finished now.

The final step is to just drag some standard RHW2 between the splitter ramps and you're done! You have a fully functional Simple Elongated Cloverleaf!

You can easily customize your clover, for example adding smoother curves to the slip lanes, or even adding accel/decel lanes, but this will require you to increase the overall size of the interchange, if it wasn't already big enough as it is. As mentioned before, this suits a more rural setting due to its low capacity, and as far as I know, no real-life versions of this clover exists. If someone can find one, that would be interesting to see.