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8-Way Intersections Measured and Compared
By RichAntDav
This guide is an accompaniment for the recent video I made comparing a number of different 8-way Intersections.
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Created by
RichAntDav
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Category: Modding or Configuration, Secrets, Workshop
Languages: English
Posted
Updated
12 Oct, 2020 @ 3:17am
1 Jan, 2021 @ 2:50am
5,035 Unique Visitors
59 Current Favorites
Guide Index
Overview
Introduction 
1. "Standard 8-Way, no Traffic Lights" 
2. "Standard 8-Way, Traffic Lights" 
3. "Large Roundabout with slip lanes" 
4. "8-way magic roundabout" by "Tremor" 
5. "8-way Double-Roundabout" by "RichAntDav" 
6. "8-Way Highway Interchange" by "RobinSinouh" 
7. "8 way snowflake interchange #2 (double cloverleaf)" by "3nƒ0я¢3я" 
8. "8-Way Quad Roundabout v2" by "RichAntDav" 
9. "8-way Ultra Interchange" by "bubbac2005" 
10. "8-Way Double Cloverleaf" by "RichAntDav" 
11. "8-Way Highway Intersection" by "Jazumojo" 
12. "8 Way Highway Interchange" by "FightBiscuit" 
13. "8 Way Interchange" by "General Grievous" 
14. "Four 3-Way and one 4-Way intersections" 
15. "Four 4-Way intersections" 
Also Check out. 
Conclusion 
Comments
Introduction
I made this guide and this accompanying video:
to show some work I've been doing recently on testing different 8-way intersection designs to see what the trade-offs are in size, cost, complexity and traffic flow performance. I also looked into whether combining smaller intersections together can be a viable alternative.

To do this testing, I created an intersection testing map which has lots of small towns around the edges and can easily be made to funnel most of the traffic through a central intersection. Intersections perform differently under different conditions so I developed 3 traffic "scenarios", namely, "light", "Moderate" and "Heavy" traffic conditions.
I used various mods, including the Network Extensions 2 DLC, Mass Transit, Traffic Manager: President Edition (TMPE) and a small custom mod I developed myself which counts and logs the number of vehicles passing over a road section.

So lets look at the intersections...

1. "Standard 8-Way, no Traffic Lights"
  • video: 0:15
  • Size: 10 x 10
  • Cost: 6,400
  • Levels: 1
2. "Standard 8-Way, Traffic Lights"
  • Video: 0:59
  • Size: 10 x 10
  • Cost: 6,400
  • Levels: 1
3. "Large Roundabout with slip lanes"
  • Video: 1:30
  • Size: 58 x 58
  • Cost: 18,240
  • Levels: 1
4. "8-way magic roundabout" by "Tremor"
5. "8-way Double-Roundabout" by "RichAntDav"
6. "8-Way Highway Interchange" by "RobinSinouh"
7. "8 way snowflake interchange #2 (double cloverleaf)" by "3nƒ0я¢3я"
8. "8-Way Quad Roundabout v2" by "RichAntDav"
9. "8-way Ultra Interchange" by "bubbac2005"
10. "8-Way Double Cloverleaf" by "RichAntDav"
11. "8-Way Highway Intersection" by "Jazumojo"
12. "8 Way Highway Interchange" by "FightBiscuit"
13. "8 Way Interchange" by "General Grievous"

14. "Four 3-Way and one 4-Way intersections"
  • Video: 11:11
  • Size: 72 x 72 (just intersections) or 130 x 130 (total)
  • Cost: 199,750
  • Levels: 2
15. "Four 4-Way intersections"
  • Video: 12:17
  • Size: 80 x 80 (just intersections) or 150 x 150 (total)
  • Cost: 237,240
  • Levels: 2
Also Check out.
Before I get to the conclusion, please feel free to check out my related guides:



Conclusion
The best 8-way intersection overall is no.13 the "8 Way Interchange" by "General Grievous", it performs slightly better at the "heavy" traffic scenario than the larger intersection (no.s 11 and 12).
None of the small (64 x 64 and smaller) intersections performed well in the"heavy" traffic scenario, but the best performing at the "moderate" level seems to be the "8-Way Quad Roundabout v2" by "RichAntDav" (disclaimer, that's me).

The most interesting part for me is the two alternatives, namely, no.14 and no.15. Getting good traffic flow in an 8-way intersection means having to use a large and expensive intersection, but you can get similar performance from multiple smaller intersections as long as there is sufficient space between them.

.
8 Comments
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e90 14 Oct, 2021 @ 7:38am 
Love it!
Conclsuion could include highest throughput, and highgest bang for buck (lowest cost per car)
Keep up the great work !
RichAntDav  [author] 1 Jan, 2021 @ 2:46am 
Thanks Fatal Justice, that reminds me, I should make it easier for people to find by including links on all the Guides :-)
Fatal Justice 31 Dec, 2020 @ 3:40pm 
Oh my goodness---you have more of these. I just found the 5 way intersection one and now this!!!
RichAntDav  [author] 23 Oct, 2020 @ 2:23am 
Hi Sasquatch, some of the intersection shown here were designed to use wider highways than the ones I used, so in that way, they may have been impacted. But from the tests I ran, the impact was quite small, however, when it comes to 6-way and smaller intersections, the effect becomes greater because I'm trying to force the same amount of traffic through a smaller number of connections. This is why in my follow-up 6-way comparison, I ran the tests using 3-way and 4-way highways.
Sasquatch 21 Oct, 2020 @ 3:33am 
Do any of these use lane mathematics? That could make a huge difference in efficiency.
RichAntDav  [author] 15 Oct, 2020 @ 1:02am 
Thanks for the comments.
Good point about the TMPE rules, some of the intersections took a lot of TMPE tweaking to get them to run run smoothly. I think it's too late for me to add them for the 8-way intersections, but I'll keep it in mind for my next video.
me22ca 12 Oct, 2020 @ 7:51pm 
8-level interchange? :steamfacepalm: I'd definitely go with 14 or 15 and just make the hole in the middle even bigger and put stuff in it -- maybe a bunch of industry and incinerators.

Amazing work! Cool to see actual data about it.

Maybe put an appendix with the TMPE rules you used on them? (Like "Hugo"ing the merge points, yield vs enter-blocked-junctions control on the ones with roundabouts, etc.)
Ｓｕｐｅｒ_Ｊ 12 Oct, 2020 @ 7:20pm 
11. is a monstrosity.:steamsad: