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Diamond Interchanges

Started by Haljackey, November 26, 2011, 01:00:51 PM

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Section 1:  Diamond Interchanges

To quote from Mightygoose's Compendium of Interchanges:

Quote"A very simple design involving two carriageways, usually perpendicular to each other however other angles are perfectly possible, of different grade (grade being quantity of traffic usually handled). The major grade carriageway in a diamond is referred to as the surface road, as it is customary that the road with higher usage has the least deviation from the horizontal. The minor grade carriageway is reflected to in this case as the street. The street may go either over or under the surface road but it will clearly undergo a greater elevation change if both routes intersect on level ground.

Diamonds are the simplest 4 ramp interchanges. They are often used in where there is a very large grade difference in the carriageways such as highways passing through inner boroughs of cities. However they scale up badly. At the ramp/street intersection, unless the street is very low grade, there must be lights. This slows down traffic, and if the street is high grade, cause congestion. Furthermore if the majority of traffic is using only one ramp of the interchange then efficient light timings are going to cause congestion on the street, especially if it is cross-carriageway turning (a left turn in the US or a right in the UK)."

Simply put, a diamond is a simple, space-saving low capacity interchange between a highway and a road.  All the road/highway interchanges Maxis included for the elevated and ground highways are diamonds and follow this concept. 

1.1: Standard Diamond Interchange
1.2: Elevated Diamond Interchange
1.3: Left Exit/Entrance Diamond Interchange
1.4: FLUP Diamond Interchange
1.5: FLUP Left-Exit/Entrance Diamond Interchange
1.6: Fractional Angle Diamond Interchange.
1.7: Video of a Realistic Diamond Interchange.

Back to the Table of Contents


Section 1.1: Standard Diamond Interchange (Created by Haljackey)

This is almost a direct copy of the RHW Readme file, showing how to make a RHW.  I will make a 4-lane RHW with a 1 tile median to keep things as simple as possible.

Place your starter pieces...

Drag the RHW using the RHW tool...

(Optional) Delete the starter pieces to create a RHW without any overrides.

And drag the stable network over it.

Voila!  You have a RHW!  Now lets make some diamond interchanges for it!

Standard RHW-type "A" diamond interchange.

From this part forward, the pictures will do most of the talking.  Note, this is just for reference, and your results can be different than mine!

Build your overpass.  For this example, I will use a simple road overpass using the NAM raised road pieces.  You can use proper land grading to create a much better looking, realistic result.

Get some RHW-2 action going now.  Drag your ramp setup at the ends of the overpass.

With those RHW-2s placed as visual examples, you now know where to plop your RHW type "A" ramps:

Connect the edge of the ramps up with the RHW-2s, and they should override to create the MIS ramps. 

All right!  You have made your first diamond interchange!

The same setup can be applied for type "C" Ramps.  Just make sure you leave enough room next to the RHW for accel-decel lanes (RHW-6S).

Standard RHW-type "B" diamond interchange.

This setup will make the ramps intersect the RHW at a 45 degree angle, which will result in a smaller, better-looking diamond interchange.

Do all the steps used in the first guide up to here:

Now, instead of plopping the RHW type "A" ramps, plop the RHW type "B" ramps.

Now, connect the edge of the ramps up with the RHW-2s and you should get your MIS ramps working.

There you go!  Another RHW diamond interchange!

Standard "Space-Saving" diamond interchange.

Up to now, all the examples I showed were possible with RHW 2.0.  Well, RHW 3.0 is out now, allowing for even more possibilities!  Here is one example.

You'll need to construct the overpass a bit differently this time, putting the new RHW/MIS 4-way intersection piece on either side of the RHW.

Use the ground to elevated MIS pieces on all four corners of the intersections you first built.

And then just use the type "A" RHW ramps to connect everything together.

Now, that's quite a space-saver eh?

The same setup can be applied for type "C" Ramps.  Just make sure you leave enough room next to the RHW for accel-decel lanes (RHW-6S).

Sunken Diamond Interchange

Two things you should get before we get started: hole-digging lots and a slope mod.

I am going to use both of them for this tutorial.  The end result will look similar to the sunken highway tutorial, but with the RHW!

Place your hole-digging lots.  (Hole diggers for sunken.)

Drag a road over each to create your hole.

Plop road stubs to level the ground properly.

Once stable enough, delete the hole digging lots and the road segments.

Dig yourself a trench.  Use road stubs for the length of your sunken segment.

Once complete, delete the road stubs.

Now construct your RHW inside the trench.  Use the steps at the very beginning of this guide for best results. 

Create your sunken overpass.

Here's where things get tricky.  Extend the sunken segment and create a sloped RHW-2 connecting the road to the sunken segment.
-Your results will probably be different than mine!

Repeat, 3 more times.

Delete any remaining road stubs and level any remaining rugged ground.

Plop the new type "A" RHW ramps that separate the RHW and MIS with a 1 tile gap in the remaining sunken areas.

You're done!  You can now rest easy.

The same setup can be applied with the "space-saver" concept displayed above.

Anyways, that will do it for now.  Have fun making some diamond interchanges for the RHW!


Section 1.2:  Elevated Diamond Interchanges. (Created by Haljackey)

The El-RHW is a real beaut when it comes to making diamond interchanges.  In this guide, I will show you how to build 3 more diamond interchanges with the El-RHW, using the El-RHW type "A" ramp and ground-to elevated MIS transitions.

Getting the basic stuff out of the way

For this guide, I will construct a El-RHW with a 0 tile median.  This makes sense as it gives the appearance that the entire highway is one structure, and because the El-RHW can easily be used in dense urban areas, a place where having a multiple tile median is rarely seen.

Place your starter pieces...

Drag the RHW using the RHW tool...

(Optional) Delete the starter pieces to create a RHW without any overrides.

And drag the stable network over it.

Congrats!  You now have a El-RHW!

Standard El-RHW Diamond Interchange

This setup is probably the easiest and most common type of elevated diamond interchanges, and is quite a space saver!

Drag a road under your El-RHW:

Place 4 ground-to elevated MIS transition pieces on each corner:

Plop your El-RHW type "A" ramps.
-Currently, this is the only El-RHW ramp.

Drag the MIS on the ground to intersect with the road and connect to the other side.

And you're done!  Pretty simple eh?  Looks great too!

Higher Capacity El-RHW Diamond Interchange

A downside to diamond interchanges is that they have a low capacity.  When space is an issue, diamond interchanges will be placed in dense cities, creating a lot of traffic problems if overused.  This setup will be better to use in those areas because it contains an extra lane at the intersection and traffic lights for better flow.

Because this is going to be higher capacity, lets put an avenue underneath instead of a road.

Drag one-way roads on either side of the RHW to create intersections.  Continue to drag them for at least one tile on each side of the intersections.

Place 4 ground-to elevated MIS transition pieces on each corner, just like we did in the last guide:

And again, plop your El-RHW type "A" ramps.

Now, drag the MIS on the ground to the one-way roads.  The ramp will widen to two lanes, allowing for dedicated right and left turn lanes and giving the appearance that it is of higher capacity.

All right!  This should work perfectly for any urban setting.

Now for something different

This guide is made for ultra-dense cities where interchanges need to consume as little room as possible.  It may not be the best looking interchange, but it will get the job done while conserving space.

Place a elevated highway/avenue interchange in the middle of the junction.  Then drag El-RHWs up to the elevated highway, leaving one tile vacant between the elevated highway and the El-RHW.
-You can also use the elevated highway/road interchange too.

Now, cycle through the raised avenue puzzle pieces tab until you find the raised avenue-elevated highway transition puzzle piece.  Place them on either side of the elevated highway in the one tile you left vacant to create a working connection.

And that's it!  The raised avenue-elevated highway transition puzzle piece can be used whenever you want to connect a El-RHW to a elevated highway.

I hope you find this guide useful!  The El-RHW is a fantastic addition, and its very useful for making interchanges!


Section 1.3:  Left Exit/Entrance Diamond Interchanges. (Created by Haljackey)

Made by request(s), I will show you how to make some diamond interchanges using the new left exit/entrance ramps included with RHW 3.0.

Getting the basic stuff out of the way

For this guide, I will construct a RHW with a 2 tile median.  You will need to have a RHW with a median of at least 2 tiles in order to get use left exit/entrance ramps for diamond interchanges.

Place your starter pieces...

Drag the RHW using the RHW tool...

(Optional) Delete the starter pieces to create a RHW without any overrides.

And drag the stable network over it.

Ok, your RHW is now set up.

Standard RHW left exit/entrance diamond interchange

Again, I will use a road as an overpass this time.  Make sure you put two 4-way El-MIS/raised road intersections in the median tiles, and make sure they are facing the right direction!

Plop 4 ground-to-elevated MIS transition pieces next to the intersections you made in the RHW's median.

...And then place the left RHW type "A" ramps next to the MIS ramps.

And you're done.  That's an odd looking diamond, eh?

High Capacity RHW left exit/entrance diamond interchange

This higher capacity interchange will not take up any additional room than the standard RHW left exit/entrance diamond interchange, and will look more at home in urban areas.  Like the higher capacity El-RHW diamond interchange, it will include an additional lane at the intersection and add traffic lights.

I will use an avenue for this diamond.  Place a 4-way raised avenue intersection in the median of your RHW.

Now use the ground-to-raised avenue puzzle pieces inside the median like so:

Place the left RHW type "A" ramps next to the avenues in the RHW's median.

Then all you have to do is drag the MIS coming from the ramp to the avenue to create a working connection.

And there you go.  Kind of a mini SPUI for those who know what I'm talking about.

After I made this guide, I decided to play around with my new interchange for a bit.  I ended up making this interesting creation:

Click for full resolution!

This 8-ramp monster handles traffic traveling in all directions.  The new outer 4 ramps handle right turns while the original 4 left ramps handle left turns.  It is truly amazing what you can make with RHW 3.0, there's just so many possibilities! 

Anyways I hope you enjoyed this guide.  That will just about do it for diamond interchanges I think.


Section 1.4: FLUP Diamond Interchange (Created by gooper1)

This interchange utilizes FLUPs (instead of overpasses) to create a space-saving interchange able to have 2-lane (RHW-4) on/off ramps (though a plain MIS is shown in this guide) for higher capacity. This interchange is best suited for urban areas.

First, put down 2 underground road (FLUPs) ramps 4 tiles apart like this:

Then, put down 2 one-way road FLUPs ENTRANCE ramps like this: (For those of you who drive on the left, use exit ramps.)

Put down 2 one-way road FLUPs EXIT ramps opposite the entrance ramps like this: (Left-hand drivers, use entrance ramps.)

Put down your RHW-4 starters and drag them out for a few tiles each way.

Place an "Underground Route under RHW-4" puzzle piece like this. You will find this piece under the road/RHW interface menu.

Now put in 4-way junctions in the gap. I used a 4-way junction with a transparent surface. It will now look like this:

Place 4 MIS style-A ramps as close as you can to the ramp. It should look like this: (close-up of one ramp)

Drag your MIS-ramps so they connect to the one-way roads. Again, a close-up:

You're finished! Your interchange should look like this:

If you want, you can use Style-C ramps or even RHW-6S>dual RHW-4 splitters in place of the type-A ramps, or an avenue in place of the road. This will give you a more efficient interchange.


Section 1.5: Compact Left Exit/Entrance Diamond Interchange with acceleration lanes (Created by gooper1)

Here is a tutorial of a left-exit/entrance diamond utilizing FLUPs (though overpasses could be used also) and the RHW-6C>RHW-4 transition with center ramps. This allows for  (in fact it must have) an accel/decel lane (unlike the existing Left-exit/Entrance Diamond tutorial), and is also more compact than the existing tut.

Put down 2 FLUPs underground road ramps like this (1 tile apart):

Put down 2 more road ramps 1 tile away from the gap between the ramps placed earlier. It should look like this:

Put down a "RHW-6C>RHW-4 Transition with Center Ramps" puzzle piece (this is found with the MIS-ramps menu, not with the other transitions) as close as you can to the ramps you put down in the first step. Then drag your RHW-4's across the gap. When that's finished, it should look like the bottom picture.

Put down a 4-way FLUP junction in the gap between the two on/off ramps. I used a 4-way junction under a pedmall. Then, put two "Straight underground route under RHW-4" pieces (make sure the lines line up) in the remaining gaps between the 4-way junction and the ramps for the intersecting road to finish your interchange. A closeup of the finished interchange:



Section 1.6: Fractional angle diamond interchange. (Created by FMK)

Here i would like to show you how to make diamond interchange with fractional angle puzzle pieces. You will need slope mod and hole-digging lots for this.

First drag the RHW-highway (i used RHW-6S), then use ground lifters to make 15m high hills. Place them 1 tile away from the RHW on each side. Drag road to set up the slope, then everything on your new hills so it looks like this:

Place "FAD-44 Type A Full" intersection on both sides (should be at least 3 tiles from your highway) and finish the overpass:

Create a gradual ascent, using the slope mod (i suggest you to make it 6 tile gradient):

Place road stubs in the end of the descent to make it look smooth:

Place "FAMIS to FARHW-4 transition B" (or continue with FARHW-4 if you want to make taper), then build FAMIS down to the highway:

Connect your loop to the RHW via any FARHW ramp (type C and type F):

You can build acceleration/deceleration lanes with some cosmetic puzzles if you want:

Finally place TULEP puzzle on the intersection:

Here is a view of completed interchange, you can place signs, lights, sound walls and other beautification  to make it look better:

I hope you will find this guide useful!


Section 1.7: Video of a Realistic Diamond Interchange. (Created by Samerton)

In this tutorial I will show you how to create a basic diamond interchange and beautify it by using narrow exit lanes and smooth curves.


Thanks Haljackey for letting me post this here.