On-ramp traffic (experienced player)

[azuarc]

You'd think after over 1000 hours in the game, I'd know how to manage my traffic, but lately my cities have been falling apart based on issues with on-ramp traffic. Example: https://steamcommunity.com/sharedfiles/filedetails/?id=2908448760

This shot isn't bottlenecked, but it highlights what I'm experiencing -- drivers getting on the highway instantly swing out at the first node to whatever lane they want for reaching their destination. In many cases, this is partnered by drivers deciding that they *then* want to be in the outer lane and veering out to prep for the next exit.

This happens regardless of lane math. This happens regardless of proximity to the next exit. And it doesn't happen at every highway entrance -- some go out one late at a time like they're supposed to -- but when it does, it can create some ridiculous back-ups that absolutely crush the entire build. What's the magic here?

[azuarc]

Better example:
https://steamcommunity.com/sharedfiles/filedetails/?id=2908456524

[OneJasonBradly]

Originally posted by azuarc:

Example: https://steamcommunity.com/sharedfiles/filedetails/?id=2908448760

This shot isn't bottlenecked, but it highlights what I'm experiencing -- drivers getting on the highway instantly swing out at the first node to whatever lane they want for reaching their destination. In many cases, this is partnered by drivers deciding that they *then* want to be in the outer lane and veering out to prep for the next exit.

This happens regardless of lane math. This happens regardless of proximity to the next exit. And it doesn't happen at every highway entrance -- some go out one late at a time like they're supposed to -- but when it does, it can create some ridiculous back-ups that absolutely crush the entire build. What's the magic here?

I Think the ramp has an improper angle or lane arrow to it making it a priority to the highway.
The clip below explains better the issue and the cure.
https://steamcommunity.com/sharedfiles/filedetails/?id=1936489145

[OneJasonBradly]

Originally posted by azuarc:

Better example:
https://steamcommunity.com/sharedfiles/filedetails/?id=2908456524

The interchange to the left (west bound):
Between the ramps you use a two lane highway. Return that back to a three lane and inspect what happens. Also the off ramp just past the interchange (again westbound) should be remove too. I think that traffic wanting that exit are waiting to the last node to switch to the exiting lane causing collisions and further slowing of the volume.
The issue on the left side I think is due to a lack of nodes between that exit and the ON ramp just before it (to the right) as traffic travels west. though in this case the extra node along the highway may not be enough. I think the ramps are too close together. I say let the offing traffic use the interchange instead of that exit there.

[azuarc]

Unbelievable. You're telling me the reason why the game won't let you build on-ramps at shallower than 35 degrees is because it needs to interpret the onramp as "turning right?"

Now, here's the odd part. That second save I showed you, where it was incredibly backed up? (More than that pic alone shows. It was nasty.) I let the simulation run for a while and it actually all cleared out. I didn't do a thing to the city. Only thing that changed is I disabled Improved Lane Connections, a mod that I had installed a few weeks ago to address a different problem within the game (the way the game prioritizes left turns over right with lane math, which results in right turns getting dedicated lanes first). Seems someone else was in the comments section recently with a vaguely similar problem, so that's probably why this suddenly became an issue for me.

Still, I have had this happen before and never understood why, so that explains it. I guess I'll have to avoid legitimately smooth on-ramps from now on. I rebuilt the onramp from the top pic, and now it actually merges correctly. So thank you for explaining this game quirk that's always frustrated me.

[azuarc]

Originally posted by OneJasonBradly:

Originally posted by azuarc:

Better example:
https://steamcommunity.com/sharedfiles/filedetails/?id=2908456524

The interchange to the left (west bound). Between the ramps you use a two lane highway. Return that back to a three lane and inspect what happens. Also the ramp just past the interchange (again westbound) should be remove too. I think that traffic wanting that exit are waiting to the last node to switch to the exiting lane causing further slowing of the volume.

Yeah, I'm sure there's some things I could have done to set that up better. That intermediate ramp was needed at one point as an escape valve, but I can probably axe it now. I don't believe that's singularly the issue, though, considering I have a similar set-up elsewhere without the extra ramp, and it's backing up there, too. This was just a nice spot to get two interchanges onto the screen at once.

[azuarc]

Okay, so after tweaking a few on-ramps, here's what I think is happening:

1) Your explanation is spot-on, and information I never had. Straight vs right is a massive difference in how the on-ramp behaves.
2) The mod I had tweaks lane connections, and I think one thing it did was influence how straight vs right was being determined at some of those nodes. I suspect the angle for getting a right arrow needed to be sharper, probably for reasons that make sense on local roads, but screw up the highway entrances.

It's possible I can go back to using the mod if I'm very mindful of what you introduced here. I'll need to inspect a little more closely. But you definitely helped me get to the root of the problem, so thank you. Many headaches in the past could have been prevented if I had only been aware.

[OneJasonBradly]

1) Very pleased you tested the claim.
2) Yes again. roads and highway have different rules to them and the ramp lane piece has rules of it's own too. You can mix and match all the pieces but they have their behaviours.
Hears another issue that mods don't fix but is easy to remedy or exploit.
https://youtu.be/sPcfHZgTBMM

[azuarc]

https://steamcommunity.com/sharedfiles/filedetails/?id=2912316254

Still having issues. ><

[caseyas435943]

Originally posted by OneJasonBradly:

1) Very pleased you tested the claim.
2) Yes again. roads and highway have different rules to them and the ramp lane piece has rules of it's own too. You can mix and match all the pieces but they have their behaviours.
Hears another issue that mods don't fix but is easy to remedy or exploit.
https://youtu.be/sPcfHZgTBMM

Or just don't build things so close together:)

Highways ramps at least 4 nodes between if not more.

You didn't really have a lot of traffic. It those were a high traffic area you'd have a nightmare. Cims and I don't care how many modes you have love to wait for that last node to change. More times than not.

Lower traffic your plan works. High traffic it won't.

Like roundabouts. You work in low traffic not high traffic.

Nice video thou. High traffic the cars would be jumping every node. So, 6 times it no road length at all. Not the bad idea. Low traffic you don't care.

[OneJasonBradly]

Originally posted by caseyas435943:

Originally posted by OneJasonBradly:

1) Very pleased you tested the claim.
2) Yes again. roads and highway have different rules to them and the ramp lane piece has rules of it's own too. You can mix and match all the pieces but they have their behaviours.
Hears another issue that mods don't fix but is easy to remedy or exploit.
https://youtu.be/sPcfHZgTBMM

Or just don't build things so close together:)

Highways ramps at least 4 nodes between if not more.

You didn't really have a lot of traffic. It those were a high traffic area you'd have a nightmare. Cims and I don't care how many modes you have love to wait for that last node to change. More times than not.

Lower traffic your plan works. High traffic it won't.

Like roundabouts. You work in low traffic not high traffic.

Nice video thou. High traffic the cars would be jumping every node. So, 6 times it no road length at all. Not the bad idea. Low traffic you don't care.

Correct in heavily congested traffic it has issues just like it would in real life. The idea is sound and works on congested traffic. I have been using this idea since 2017 in everyone cities where lane jumping occurs and it works very well. If you have a large volume of traffic and they are jumping all about then the traffic is trying to point you to something. They are in a panic state and don't understand the roadwork you have made. Or it doesn't follow their rules so they ignore the rules and try to get to point "B". which results in single lane traffic behaviours. It is that simple. The point I was expressing IS YOU NEED NODES TO CHANGE LANE TO OR THEY WILL LANE JUMP. If there is no other issue present.

[OneJasonBradly]

Originally posted by azuarc:

https://steamcommunity.com/sharedfiles/filedetails/?id=2912316254

Still having issues. ><

This shows lane forcing or lane reservation rules being enacted. This (Your) issue is not here but further down the highway.
Here's some example of that behaviour.
https://youtu.be/sQrw31QzJxw
and the repair or the beginning of the repair to the roundabout
https://youtu.be/HUQRCl5SD-Q
This traffic is stuck in the far left lane like yours.
https://youtu.be/y6pl3i7O5FI
https://youtu.be/ShMGOKBUut4

[OneJasonBradly]

Originally posted by azuarc:

https://steamcommunity.com/sharedfiles/filedetails/?id=2912316254

Still having issues. ><

If you can't figure where this issue is I would suggest you to share the town so that we/I may inspect it for you and help explain what happened better. If not we will keep at it here. Nice and very descriptive screenshot you posted, thanks. Though it is showing the symptom and not the cause. To get closer to the cause follow this left laning highway traffic to the point where they stop using only the left lane. Most likely at a ramp. That's a shot I would be interested in seeing. Just like in the highway repair video I posted here.

[azuarc]

It is indeed at a ramp. A single lane ramp when there are three to choose from, and plenty of nodes in-between. I see no reason why the middle lane would be vacant.

I dislike uploading saves because i get self-conscious about my city's design, but https://steamcommunity.com/sharedfiles/filedetails/?id=2912602053 is the file.

Looking at it, yes, it's reserving two lanes. The in-bound traffic isn't using the middle lane, but the existing traffic that wants to get off is sliding into the middle lane and hopping to the right immediately before the exit. I don't understand why, though. TBF, it's a temporary interchange because I haven't activated 81 tiles and this is the edge of 25. I intend to build a better interchange Some Day (tm) if I get that far with the map. But when stuff like this happens, I lose interest in the save.

Further edit: I played with adding lanes for the hell of it, so 4 before and 3 after the offending exit, and the traffic eventually cleared. It's still very much disregarding the second lane from the right.

[OneJasonBradly]

of course I can open Rennes but not this.

[OneJasonBradly]

They ignore the middle lane?
It's the interchanges. Possibly
https://steamcommunity.com/sharedfiles/filedetails/?id=2912316254
https://steamcommunity.com/sharedfiles/filedetails/?id=2908456524
The sections that have been reduced to two lanes highways bring them back to three lanes.
Instead add a four lane before or leading up the only the OFF ramps.
Because of the placements of the two lane highway pieces it is reserving most right lane as exit and the middle lane for the next exit forcing through into the left.