Stack Interchanges

Started by Haljackey, November 26, 2011, 02:14:42 PM

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Section 18: Stack Interchanges

Stack interchanges eliminate the problems of weaving and have the highest vehicle capacity among different types of four-way interchanges. However, they require considerable and expensive construction work for their flyover ramps. Stack interchanges are also widely considered to be an eyesore among residents of homes near existing or proposed interchanges, leading to considerable NIMBY opposition.

The four-level stack has one major road crossing another on a bridge, with connector roads crossing on two further levels. This type of interchange does not usually permit U-turns. Interestingly, the four-level stack creates two "inverse" dual-carriageways—the turn ramps crossing the middle section have traffic driving on the opposite side of oncoming traffic to usual.

18.1: Sunken Stack Interchange (Haljackey's Way)
18.2: Sunken Stack Interchange (McDuell's Way)

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Section 18.1: Sunken Stack Interchange (Created by Haljackey)

This is probably one of the most demanded guides out there. Building a true four-level stack interchange is not possible with the current RHW (Version 5.0 at the time this guide was written) but it is possible to 'cheat' by creating two sunken levels of tunnels for the main routes. The flyovers would be on the ground level and one level above that.

Before undertaking this guide, be sure you have the following:
-A good terrain elevation above sea level. With two levels of tunnels, you will need to dig deep into the earth.
-Hole digging lots.
-Slope mod (optional but highly recommended)
-A basic understanding of the RHW. This guide is not recommended for beginning users.

The first thing you will need to do is construct a few MIS ramps that have a setup similar to this.
-You will need at least a 4 tile gap between the two MIS spans.

Place your MIS-elevated MIS ramps in a mirrored version like so:

Now drag all 4 of your ramps towards the middle but leave the centre part free.
-You can also build your outer ramps now as well.

Use diagonal el-MIS over diag-MIS pieces in the centre of the junction. Be sure the lines match up correctly. (In stacks the flyovers run in the opposite flow of traffic so watch out!)
-Use filler pieces for the diagonal MIS and diagonal el-MIS to hook the central part up with the rest of your junction.

Congrats! You've now made the ramps for your stack interchange! Just take a moment to clean it up (I delete all MIS past the outer ramps)

Now time to build your tunnels. Place avenue hole diggers (14m) in the median like so:

Drag one avenue tunnel and place road stubs in the other trench of the other.

Drag RHW-4 from your avenue tunnels and place rail hole diggers (8m) in the trench where your road stubs were.
-Rail hole diggers lower the ground to 22m. Another avenue hole digger would lower it another 14m (28m total) which is a depth not needed.)

And drag avenue tunnel to create your second underpass.

Drag RHW-4 from your second avenue tunnel. Use the RHW-4 type A-wide ramps to connect your MIS ramps to the RHW where the RHW transitions to level terrain.

Do the same for the other RHW. The ramps will be a little further away due to the fact that the RHW has to climb out of a lower grade.

And congrats! You've created a basic sunken stack interchange! Looks good too eh?

Anyways hope you enjoyed the guide!

If you have any questions about this guide or any other, feel free to post in the support thread.


Section 18.2: Sunken Stack Interchange (Created by McDuell)

This section shows you a second approach for building this type of interchange.

If you want, put down some rail pieces in the center of the interchange to be built. While not necessary, they may help while placing the first puzzle pieces. You may bulldoze them after the next step.

Now, select the diagonal EMIS over diagonal MIS type 1/2 puzzle pieces and place them exactly as in the picture. It's important that the orientation of the pieces is correct. The yellow lines should be pointing outwards.

Here is the same setup with drawpaths on and the rails bulldozed.

Put down some single rail pieces to prevent the RHW from possible autoconnecting. Now draw the flyover lanes as shown.

When you are finished, it should look like this.

Place hole digger lots for building the tunnels afterwards. It doesn't really matter if you use Avenue or OWR tunnels. Just be sure to leave enough space for the terrain for auto-conforming to the tunnel entrances, as shown with the rail.
For best results, you can build the tunnels at different levels. In this tutorial, I used the -8 and -14m diggers.

Prepare the slopes for the tunnels. You might get different tunnel ramp lengths than me depending on your slope mod.

Bulldoze the digger lots and build the tunnels.

Put down MIS <-> EMIS transitions as shown in the next picture. Be sure that you use the one with the starters.

Place ground MIS starter pieces to build the curves for the other pair of 'flyover' ramps.

Bulldoze the end of the starter pieces.

Complete the left turn ramps with diagonal MIS and EMIS filler pieces.

Use the drawpaths cheat again to check if everything is correct so far.

Place RHW4 tpye E1 entrances and exits and connect the MIS gaps. Do this for all branches.

Connect all right turn ramps.

Put down RHW4<->FARHW4 outer ramps and seamlessly add RHW6S Type C2 exits and entrances. Again, we need this for all branches.

We're almost done.

Bulldoze any leftover helper network pieces and connect the missing RHW parts.

Finished! :)

It's redundant, it's redundant. (R.E. Dundant)