How to build a transit network just above the tunnel entrance?

[sneekypetepuma]

Lets consider that the ground level freeway is a tunnel.. is it at all possible to make a flyover ramp like the one pictured

[Ennedi]

First of all let's translate your problem to the SC4 language 

As I understand looking at your picture, we have 3 roads in total:
1. Ground highway - let's call it A - going from top to bottom of the picture;
2. Elevated highway - let's call it B - going from left to right;
3. The flyover - let's call it C (this is an exit, so I think it can be an OWR) on the left side, going down from A, crossing B, turning left, crossing A and then connecting with B.
(If I made any mistake or your problem is different, improve me please).

So we should have 2 flyovers:
F1 - C over B
F2 - B over A and C over A (in fact these are 2 flyovers going parallel one close to another, we will see how close , and I consider them as one complex engineering structure).

The answer is:
Of course it is possible to do, but you must remember about following things:
- B is a multilane highway on your picture. It can cause serious problems with both F1 and F2. So it would be much better if B could be a normal elevated highway.
- The minimum length of the tunnel is 3 tiles.
- The last section of C (going parallel to B) should be at least one tile away from B to make an onramp and enable traffic from C to B.
- Due to the SC4 limitations the whole junction probably will not be such elegant as on your picture, but it can be done quite good and functional

The solution should be showed on examples, but I must to ask you for some patience - now we have 7.31 AM in Central Europe and I'm preparing to go to work. I can make some examples for you today evening or tomorrow.

[rooker1]

This going to be great, I can't wait to see what Ennedi comes up with.   

Robin   

[Ennedi]

@sneekypetepuma,

Here is an example how to solve your problem.
Your question is a little off-topic here, because you don't need to make any tunnel and you don't need to drag any network just above the tunnel entrance. But it is interesting by itself and maybe my answer will be useful for you.

OK, let's go
Network names - as in my previous post.
Start: I make highway A (North - South). Then I'm raising the terrain along it using the Ground Lifter from the Hole Digging lots set. It raises the terrain by 15 m. This height is good for using network puzzle pieces and the projected flyover will be flat.



To drag the highway B (East - West) over A I will use a puzzle piece "Straight Highway on Slope", wchich comes with the new NAM. It is 5 tiles long. Using it we need a sunken area along A at least 6 tiles wide.



Now I drag B over A:



Why I didn't make all B as an elevated highway? Because I want to make a flyover C over B (left side of the picture) and an exit on B (right side). It will be much easier to have a ground highway to do it.

Now I make an exit. I use the Euro type highway exit (new NAM, under the "Custom Interchanges" button in the highway menu). This way I will have not only an exit from A to B, but also from B to A. Of course you can use One-Way Road 



Now I will build a road. I don't want to make a curve like below:



Instead of it I make a bit longer curve, it will look better:





Now I make the flyover (C over A) using Road Puzzle Pieces







Now I must build the next flyover, C over B. I'm raising the terrain



Drag a road



...And soften it



I make the curve (in the same way as earlier)



...And build the flyover



Now I make an exit on the A highway (A turns right as on the original picture)



And then I connect it with a road using wide curves



OK, the connection between exits on A and B is ready (of course if I would build a complete junction, I would need 3 roads more, or 6 OWR more - but it is only a question of proper planning and the available space. There are many possible ways to do it, we could also use Big Dig pieces, Marrast Underpasses and so on).
Now I want to finish this area using walls. I choosen the Japanese Walls Set (MAS71) - Wall No. 4. But we have a problem here - diagonal walls look bad:



It's an interesting side theme, because it is a common problem with making diagonal walls.
So we will make a little diggression: How to avoid these stupid walls?
The answer is: We must make the wall higher (by raising it's top or lowering the bottom).
How high should be the wall? About 30 m - you will know that it is done when you will see the rock texture
Look at terrain levels on pictures below:







My highway is ready, so I can't raise the top, I must lower the base



( I use an ingame lowering tool set as Shift+1, Shift+F2 - look at my tutorial here

OK, it's enough (highway level 282 m, base level 251,4 m, the difference is 30,6 m)



I had to be careful, the sea level is 250 m 
To make a wall 30 m high you can also use the Ground Lifter or sunken tool (2 times, 15 m each time)
...And the wall is ready



Now we should only flatten unnecessary hills and make walls. And here is the final effect:









Of course you can do the same thing using One-Way Road. The only difference will be at exits, you must do something with the free end of the OWR



You can build here a service road, parking etc.

End notes:
1. You can make larger curves here



And here



But you will need more space in this case.

2. You can make a tunnel here instead of flyovers:



In this case you will need only 2 tiles wide space instead of 6 and all junction will be smaller. But think about it first, this space along A can be useful when you will make other exits.

3. Edit: I checked your posts at the "Compendium of Interchanges" thread. I see our first question was: It is possible to make a flyover over an elevated highway?
The answer is: No (not yet ), but you can make on an elevated highway a short part of ground highway, and then make a flyover in this place. You can make it practically invisible - it's only a question of creativity and some experiments
Good luck!

[RippleJet]

You're an excellent tutorial maker, Adam!

[Ennedi]