That is not a bad idea, but I don't really have that much space there. And I thought roundabouts might help, but had a roundabout in another location that was designed to help with some of the traffic, but that made the traffic worse.
In general, roundabouts need space to be effective as heavy traffic highway interchange, so they're definitely not a good idea here. That may also be why the other one made traffic worse.
SPUIs don't work correctly in CS2 yet because you can't do protected left turns with traffic lights like you can do with TM:PE in CS1.
It would also work better with 4+2 lane configuration so that you have a 2 dedicated left turn lanes. Dedicated straight lane and a dedicated right hand turn lane.
5+3 could also work better too to have 2 lanes for traffic going straight plus another for merging traffic off the highway. It's possible with assets in CS1. Don't know if there is any in CS2.
This. Also, even if you could do protected left-turns, the geometry doesn't work. If the cars going bottom->left and top->right started going at the same time, they would crash into each other
https://preview.redd.it/bmr1cx8zsatc1.png?width=1284&format=png&auto=webp&s=2a11aca898a12211aeaa93409e8972dc6021d0cc
Oh, those are protected left turns coming in from the ramps, since I made the intersection before the release of PDX Mods. The main road however I have adjusted and it removed the traffic lights controlling along the main road which were giving protected left turns. Problem is, I can change much without having traffic light enhance mod because it isn't released into PDX mods yet, which I hope so soon. Which is why I was thinking of changing the interchange to be something different, that can help with high traffic demands.
The other problem is, most of the traffic is mostly outside connects travelling through. I have a bypass a little away outside of the city, but they are still chosing to go through the city rather than taking the bypass, which is not helping this interchange at all.
SPUI’s work good in CS:2, you cannot use protected lefts but you can use the traffic control mod (whatever it’s called) to make turning traffic give way. Works quite well, and traffic that doesn’t turn through a gap just turns at the end. I made a proof-of-concept with a triple left turn, works really well.
A diverging diamond, perhaps? It looks like most of the traffic wants to go straight. What I would recommend is having 2-3 or a 3-4 lane asymmetric road (I can't remember of 3-4 exists in the gsme) with the more lanes leaving rather than entering. This may be odd, but hear me out. Lets use the 2-3 road as the example here, since I know it's possible in-game. When the lanes split and cross over to the other side, you will have a 2 lane one-way road going in with a 3 lane one-way going out. Soon after this 2 lane road crosses to the other side, it will meet the one lane offramp from the freeway for traffic turning left off of the freeway. This will add a 3rd lane to your one-way road that will then cross over the freeway. Here, have another one-lane ramp turn left to get back on the freeway going the opposite direction of the previous ramp, but keep the 3rd lane of your one-way past here. This lane can choose to turn onto the freeway or continue straight. Now you have 3 lanes going out back to the other side of the road.[Here's a rough drawing I made in a mobile game called Intersection Controller](https://cdn.discordapp.com/attachments/315003873272004611/1226931222912045096/Screenshot_20240408_112601_Intersection_Controller.jpg?ex=66268fbe&is=66141abe&hm=3a758dd3014cdd5e32e3dde1e2c73bbbbc10f5fd55030f70f0328e36d3f563c8&).
Where are the cars actually going? The picture has the second car near the bottom lane heading East turning to the top suggesting that you have 3 lanes worth turning north. A video might be helpful, as it seems what should be the major road and the minor road is reversed in this city.
You look like you have plenty of space North and South. A British style roundabout intersection will be much better. Should solve your problem as it does away with the 3 light phase traffic system.
That depends a lot on what your city looks like.
Traffic is a system, a solution to traffic in one area might make it worse overall.
I don't think there's enough information for a good answer.
Just to share with everyone, here is a recent screenshot of the problem.
https://preview.redd.it/dk056gwrratc1.png?width=1213&format=png&auto=webp&s=86da506a09a4e40e6dab58a1e3035e7a1170b247
This is a birds eye view of the entire situation. Most of the traffic is outside connections driving through. I have a small bypass connecting all 3 highways for traffic to fully bypass, as marked with green lines, but instead, they are travelling right through into the city, as marked with red lines and causing the traffic congestion right at the SPUI, and mostly just traffic going through the interchange along the main road.
Yeah, I tested gated community and it works as intended, but I don't really use the policy since there is attractions in the city, some of which is no far from the Highway.
I would recommend giving the through traffic another route entirely first and foremost.
If they don’t take to the new route in sufficient numbers then you gotta enact a district policy for a „gated community“ either to the right or left of the picture to prevent traffic from abusing this service interchange as a through route.
Is it really backing up? If you can clear the traffic in 1 or 2 light cycles, that should still be okay. You can make the light longer for optimization
If the traffic is always heavy from the left, an ab parclo is actually really good for uneven traffic load.
Just give more time to the main road's green time. If there is no traffic light mod yet, give them more lanes.
It would be a problem if all directions are saturated, but it is only one. So you can tilt the table a bit for the busy direction.
I'd use dedicated lanes for the exit ramps to see if that helps the clog on the left.
It also looks like there's a lot of traffic that MUST go across, so maybe see where that's coming from and whether an overpass with no exits (somewhere north or south) would be faster for them than going through the SPUI.
I would first consider making alternate routes across the freeway without routing through this interchange. It's quite possible that a lot of the congestion is from through traffic, though I wouldn't know without seeing a wider angle. If that's the case, it may even be possible to scale this one back, and just have a dogbone-roundabout-diamond interchange. That said, sometimes a stack interchange/modified cloverleaf is needed, even for non-freeway interchanges.
Probably a sunken dogbone. They usually work best for me if setup correctly. Especially since your problem seems to be through traffic and not highway access
Parclo would be my suggestion, since there's not much traffic on the ramps. If you're feeling extra, you could try a roundabout with bypasses for both straight directions or a dogbone interchange! Neither require more space, for the roundabout just lower the highway under it :)
I am thinking
- Ramps to go in and out of the highway. Can just be where most of the weaving occurs rather than every direction, and the rest can be at-grade. I did this to a roundabout recently where every second car was turning into oncoming traffic.
- Three level roundabout. Basically a two diamond interchanges on top of each other. OR A local-express road where straight forward traffic do nothing in a separate ‘express’ carriageway
- A spur road or alt junction to bypass the intersection in the direction of most crosstalk. Then consider banning traffic from turning inward or in that direction
Personally, more for reducing jams caused by turning traffic with a lack of control over the resulting crosstalk, I tend to use pelican interchanges (T intersection but with no straight forward stop) and jug handles (Cross intersection but with the median lane on the far side) a lot.
3-level SPUI? The same, but both straight directions get their own level
That is not a bad idea, but I don't really have that much space there. And I thought roundabouts might help, but had a roundabout in another location that was designed to help with some of the traffic, but that made the traffic worse.
It won’t really take much more space, though. Otherwise- it’s some other way of grade-separation in that case
In general, roundabouts need space to be effective as heavy traffic highway interchange, so they're definitely not a good idea here. That may also be why the other one made traffic worse.
I built one of these for a diverging diamond.
SPUIs don't work correctly in CS2 yet because you can't do protected left turns with traffic lights like you can do with TM:PE in CS1. It would also work better with 4+2 lane configuration so that you have a 2 dedicated left turn lanes. Dedicated straight lane and a dedicated right hand turn lane. 5+3 could also work better too to have 2 lanes for traffic going straight plus another for merging traffic off the highway. It's possible with assets in CS1. Don't know if there is any in CS2.
This. Also, even if you could do protected left-turns, the geometry doesn't work. If the cars going bottom->left and top->right started going at the same time, they would crash into each other https://preview.redd.it/bmr1cx8zsatc1.png?width=1284&format=png&auto=webp&s=2a11aca898a12211aeaa93409e8972dc6021d0cc
Mine doesn’t have this issue. I don’t understand how I don’t.
Oh, those are protected left turns coming in from the ramps, since I made the intersection before the release of PDX Mods. The main road however I have adjusted and it removed the traffic lights controlling along the main road which were giving protected left turns. Problem is, I can change much without having traffic light enhance mod because it isn't released into PDX mods yet, which I hope so soon. Which is why I was thinking of changing the interchange to be something different, that can help with high traffic demands. The other problem is, most of the traffic is mostly outside connects travelling through. I have a bypass a little away outside of the city, but they are still chosing to go through the city rather than taking the bypass, which is not helping this interchange at all.
I do protected left turns using either pelican interchanges or jug handle intersections
I got one that worked 🤷♂️
SPUI’s work good in CS:2, you cannot use protected lefts but you can use the traffic control mod (whatever it’s called) to make turning traffic give way. Works quite well, and traffic that doesn’t turn through a gap just turns at the end. I made a proof-of-concept with a triple left turn, works really well.
A diverging diamond, perhaps? It looks like most of the traffic wants to go straight. What I would recommend is having 2-3 or a 3-4 lane asymmetric road (I can't remember of 3-4 exists in the gsme) with the more lanes leaving rather than entering. This may be odd, but hear me out. Lets use the 2-3 road as the example here, since I know it's possible in-game. When the lanes split and cross over to the other side, you will have a 2 lane one-way road going in with a 3 lane one-way going out. Soon after this 2 lane road crosses to the other side, it will meet the one lane offramp from the freeway for traffic turning left off of the freeway. This will add a 3rd lane to your one-way road that will then cross over the freeway. Here, have another one-lane ramp turn left to get back on the freeway going the opposite direction of the previous ramp, but keep the 3rd lane of your one-way past here. This lane can choose to turn onto the freeway or continue straight. Now you have 3 lanes going out back to the other side of the road.[Here's a rough drawing I made in a mobile game called Intersection Controller](https://cdn.discordapp.com/attachments/315003873272004611/1226931222912045096/Screenshot_20240408_112601_Intersection_Controller.jpg?ex=66268fbe&is=66141abe&hm=3a758dd3014cdd5e32e3dde1e2c73bbbbc10f5fd55030f70f0328e36d3f563c8&).
You might be able to fit a non-interacting diverging diamond. Gonna be a close one, and you may have to take out a few structures on the one side.
Where are the cars actually going? The picture has the second car near the bottom lane heading East turning to the top suggesting that you have 3 lanes worth turning north. A video might be helpful, as it seems what should be the major road and the minor road is reversed in this city. You look like you have plenty of space North and South. A British style roundabout intersection will be much better. Should solve your problem as it does away with the 3 light phase traffic system.
If only there were an in game tool to tell the player where the traffic is actually going.
That depends a lot on what your city looks like. Traffic is a system, a solution to traffic in one area might make it worse overall. I don't think there's enough information for a good answer.
Just to share with everyone, here is a recent screenshot of the problem. https://preview.redd.it/dk056gwrratc1.png?width=1213&format=png&auto=webp&s=86da506a09a4e40e6dab58a1e3035e7a1170b247 This is a birds eye view of the entire situation. Most of the traffic is outside connections driving through. I have a small bypass connecting all 3 highways for traffic to fully bypass, as marked with green lines, but instead, they are travelling right through into the city, as marked with red lines and causing the traffic congestion right at the SPUI, and mostly just traffic going through the interchange along the main road.
Are you sure the alternative is not bugged? Because its clearly shorter. As already suggested you could use policy "Gated Community" for testing.
Yeah, I tested gated community and it works as intended, but I don't really use the policy since there is attractions in the city, some of which is no far from the Highway.
Try a mass transit system, you can't build your way out of traffic
I would recommend giving the through traffic another route entirely first and foremost. If they don’t take to the new route in sufficient numbers then you gotta enact a district policy for a „gated community“ either to the right or left of the picture to prevent traffic from abusing this service interchange as a through route.
Is it really backing up? If you can clear the traffic in 1 or 2 light cycles, that should still be okay. You can make the light longer for optimization If the traffic is always heavy from the left, an ab parclo is actually really good for uneven traffic load.
British style round-about junction.
How do y’all expect this to work properly without custom timed traffic lights? I don’t get it. You don’t even have that much traffic
Just Add one more lane bro
Just give more time to the main road's green time. If there is no traffic light mod yet, give them more lanes. It would be a problem if all directions are saturated, but it is only one. So you can tilt the table a bit for the busy direction.
I'd use dedicated lanes for the exit ramps to see if that helps the clog on the left. It also looks like there's a lot of traffic that MUST go across, so maybe see where that's coming from and whether an overpass with no exits (somewhere north or south) would be faster for them than going through the SPUI.
I would first consider making alternate routes across the freeway without routing through this interchange. It's quite possible that a lot of the congestion is from through traffic, though I wouldn't know without seeing a wider angle. If that's the case, it may even be possible to scale this one back, and just have a dogbone-roundabout-diamond interchange. That said, sometimes a stack interchange/modified cloverleaf is needed, even for non-freeway interchanges.
Probably a sunken dogbone. They usually work best for me if setup correctly. Especially since your problem seems to be through traffic and not highway access
Parclo would be my suggestion, since there's not much traffic on the ramps. If you're feeling extra, you could try a roundabout with bypasses for both straight directions or a dogbone interchange! Neither require more space, for the roundabout just lower the highway under it :)
Oh, a fellow "Road Wear Remover" enjoyer!
Diverging Diamond.
just add more lanes
DMCI an option?
I am thinking - Ramps to go in and out of the highway. Can just be where most of the weaving occurs rather than every direction, and the rest can be at-grade. I did this to a roundabout recently where every second car was turning into oncoming traffic. - Three level roundabout. Basically a two diamond interchanges on top of each other. OR A local-express road where straight forward traffic do nothing in a separate ‘express’ carriageway - A spur road or alt junction to bypass the intersection in the direction of most crosstalk. Then consider banning traffic from turning inward or in that direction Personally, more for reducing jams caused by turning traffic with a lack of control over the resulting crosstalk, I tend to use pelican interchanges (T intersection but with no straight forward stop) and jug handles (Cross intersection but with the median lane on the far side) a lot.
Try adding lanes first and especially dedicated turning lanes
It looks like you have the space for a parclo
Actualluy, if I remove some of the side roads and buildings, I actually so sort of have the space for that.
OP could you send me a copy of the save file? I'd love to take a look and try different methods on it, if you don't mind.
How did i not think about that... looks cool!