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Dumbbell and Raindrop Interchanges

Started by Haljackey, November 26, 2011, 01:14:30 PM

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Section 5:  Dumbbell and Raindrop Interchanges

I wanted to devote a section of this guide for dumbbell and raindrop interchanges.  It shares many similarities with diamond interchanges (which are shownin section 1) but instead of having intersections where the on/off ramps meet the road, a pair of roundabouts are used. 

Ireland uses dumbbells a lot, particularly on rural, lower capacity roads.  This design is both compact and efficient because traffic does not stop, and they look pretty good in SC4 too.

It is also important to note that the RHW should overpass the road, not vice versa, because the road expands to contain roundabouts not far from the centre of the interchange.  You will see this in the guides to come.

There are a lot of difficulties to consider when building a dumbbell interchange for avenues.  The workaround: don't use roundabouts! Use a Raindrop Interchange! It is known as a raindrop interchange because in real life each side can look like a drop of water hanging from a faucet without the roundabouts.

5.1 Basic Dumbbell Interchange
5.2 Elevated Dumbbell Interchange
5.3 Sunken Dumbbell Interchange
5.4 Avenue Dumbbell/Raindrop Interchange

Back to the Table of Contents


Section 5.1: Basic Dumbbell Interchange (Created by Haljackey)

*Since we're already at page 6 of this thread, the starting picture will not be as basic as in earlier pages.  If you have trouble making the setup in the first picture, than I suggest looking at past guides for a detailed start-up.

Drag road.  Construct a RHW overpass over the road like so:

Construct two one-way road roundabouts directly next to the RHW overpass (0 tile gap).
-Refer to your NAM Readme file if you do not know how to construct a one-way road roundabout.

Plop 4 RHW-4 type "A wide" ramps at the edges of the overpass, facing toward the road/roundabouts:

Using the RHW tool, drag MIS from the ramps to the edges of the roundabouts.

Voila, you're done!  Pretty simple eh?  This marks the shortest tutorial in this guide!


Section 5.2: Elevated Dumbbell Interchange (Created by Haljackey)

This small guide will show you how to build a dumbbell interchange using an El-RHW.  These work best in tight urban areas because they are small, free-flowing interchanges.

Start out by dragging your El-RHW over a road.

Build 2 one-way road roundabouts on either side of the overpass. 
-Unlike the last guide, they do not have to be 0 tiles away from the RHW, but it helps to keep them close to conserve space.

Drag 4 segments of RHW-2 from the roundabouts so that they meet parallel to the El-RHW like so.
-Do not curve the RHW-2 immediately before it intersects the roundabout.  Leave an extra tile or two so the network overrides to on/off ramps correctly.

Plop 4 ground/elevated MIS transitions where the RHW-2s end.  Make sure the white and yellow lines on the MIS align with the El-RHW to ensure a proper connection.
-The RHW-2s should now change into MIS.

Finally, plop 4 El-RHW type "A" ramps where the El-MIS begins to complete the interchange.

...And that's it!  You now have a working, efficient elevated dumbbell interchange!


Section 5.3: Sunken Dumbbell Interchange (Created by Haljackey)

This one's a little more detailed, as you need to properly grade and slope your interchange.  It results in a very realistic looking interchange.

*Hole digging lots are required for this guide. In addition, using a slope mod is recommended.

Plop a couple hole diggers for sunken to create your trench.

Drag road from them to form the sunken route.

Demolish everything.  Place two road stubs in the sunken segment of land.

Continue to place road stubs to finish your trench.

Demolish the road stubs and drag RHW where they once were.

Drag your road.  Create an on-slope overpass over the sunken RHW.

At the edges of the overpass, create two one-way road roundabouts.
-Its best to leave a 0 tile gap here.

Time to place more road stubs :P.  Place them from the RHW out to the centre tiles of your roundabouts like so:

Demolish the stubs and drag 4 segments of RHW-2 from the roundabout to the sunken section.
-The remaining road stubs in this image shows where the RHW-2s are level with the RHW.  This may be closer to the roundabouts if you're using a slope mod that is not as restrictive as mine.

Begin to curve your RHW-2s toward the RHW.  This will indicate where to plop your entrance/exit ramps.

Plop 4 RHW-4 type "B" ramps to join the RHW-2s with the RHW.  They should now change to MIS near the ramp.

Redraw your ramps and fix your slopes to complete the interchange.

And you're done!  That's a realistic looking sunken dumbbell interchange! 


Section 5.4: Avenue Dumbbell/Raindrop Interchange (Created by Haljackey)

As mentioned in the above posts, there are a lot of difficulties to consider when building a dumbbell interchange for avenues.  The workaround: don't use roundabouts! 
-This guide will show you how to create such a junction.  It is also known as a raindrop interchange because in real life each side can look like a drop of water hanging from a faucet without the roundabouts.

I will show how to build this with a sunken route and on the ground level.

Fully Sunken Avenue Dumbbell Interchange

Here is step one.  Construct a sunken RHW and create two one-way road "on-slope" overpasses.  Be sure they are two tiles apart from one-another and everything is facing the right direction.
-See my earlier guides if you do not know how to create a trench for your RHW networks.

Set up your avenue/surface street.  Create a bulge in the gap between your one-way roads by dragging them an additional tile apart on either side.
-Leave 1 tile of uncurved one-way road in the middle.  This is where your on/off ramps will connect.

Connect your one-way roads with your avenue.  Make sure you create a connection between your one-way roads as well.  There are two ways to do this.



I am going to use the second connection style for this guide because, while not as direct, it gives the interchange a distinct, well rounded shape.

Take a pause for a moment to make sure everything is connected in the right direction.  You've now completed the overpass and setup for the ramps.


Now its time to make the ramps.  Drag 4 sections of RHW-2 from the one tile of uncurved one-way road you left.

Create some slopes for your ramps.  Use road stubs and drag parallel sections of RHW-2s to make it as smooth as possible.

Demolish everything but your connecting RHW-2s and curve them toward the RHW.

Plop 4 RHW-4 type "B" ramps to connect with the RHW-2s.
-This picture shows two of the four connections.

Redraw your RHW-2 networks to convert them to your on/off ramps.  Congrats, you completed the interchange!

Sunken to ground Avenue Dumbbell Interchange

This time the only part of the RHW-4 needs to be sunken to create the overpasses for the one-way roads. 
-If this was elevated, the one-way road overpasses would be longer and would make the bulge further away from the RHW.  This would dramatically increase the size of the interchange.
-The setup for the overpass remains the same.

Drag your RHW-4 back up to ground level.
-Remember, this time it is the RHW mainline that is being graded, so the smoother the slope, the more realistic.

Here's a smoother way to slope your RHW, use a bullet train line to create the smooth grade for you.
-The slope mod for the bullet train is one of the smoothest in the game.  It is built into the Bullet Train Mod (BTM), which you can download HERE.

The result is an extremely smooth, realistic slope.  Just compare this to the one made with the RHW slope mod two steps ago!

This time, drag 4 sections of one-way road from the one tile of uncurved one-way road you left diagonally towards your RHW.  Stop curving one tile away from the RHW.

Now, plop 4 RHW-4 type "A wide" ramp pieces where the slope on your RHW ends.  This will vary depending on the slope of your RHW.
-Drag the ramps from the ramp pieces to connect with your one-way roads.
-This picture shows two of the four connections.

Voila!  You're done.  Here's a shot of the interchange from far away:

Anyways, that's it for now.  I hope this guide has inspired you to make some avenue dumbbell/raindrop interchanges!  Their capacity is much higher than standard diamond interchanges and they don't take up much more space.