Tips for Managing highway traffic?

[no one]

Hi all,

I am experiencing very severe traffic jams on my highway near my downtown area. I have a major industrial area just up the highway from the majority of my residential/commercial buildings, and to help prevent trucks from driving through neighborhoods I have designed the highway as the only way in/out of the industrial area (there is a tollbooth that also bridges industry/the rest of the city but not too many trucks use it which is ideal for me). I have multiple overpasses with on/off ramps to help trucks leave the industrial park and then to also get into the city proper, with the road leading directly into intersections in downtown or adjacent areas to try and help dillute the traffic flow. On/Off-ramps are controlled by stop lights - otherwise I try to minimize lights/stop-signs as much as possible for fastest traffic flow. Things were never great but they were tolerable for a long time until now - my city is a lot bigger and the highway/exits are overwhelmed with bumper-to-bumper traffic. I am using four-lane highways (can't remember if it's a mod but they're useful!) and two-lane highways as off-ramps.

How do you guys structure your highways and road construction for good traffic flow? I am not using any traffic mods (yet). I am pleased with my current city as I have been more careful with road planning and making better use of four- and six-lane roads, and it paid off nicely up until now, so I think it's time for me to go back to the drawing board and learn some more techniques before I make things worse.

Thanks in advance!

Edit: Screenshots showing progress:

Start: https://steamcommunity.com/sharedfiles/filedetails/?id=1616304792

After building underground highway roundabout under Downtown: https://steamcommunity.com/sharedfiles/filedetails/?id=1619216573

After building highway exit roundabouts for the industrial park: https://steamcommunity.com/sharedfiles/filedetails/?id=1619689749

[gingerboyz4]

u should post pictures or the save

[no one]

https://steamcommunity.com/sharedfiles/filedetails/?id=1616304792

Originally posted by gingerboyz4:

u should post pictures or the save

Here you go

[Philip]

In my (perhaps limited) experience, there are many things that can affect traffic flow, and part of the fun is playing around with it to see what works.

One general rule I've found is that to get high traffic flow, you want everything to flow without interruption. In fact, flowing without interruption seems more important than having more lanes. Stoplights and turns that cross opposing traffic both cause interruptions.

So in your case, the first thing I'd look at is the overpasses, which have both left turns and traffic lights. You could try replacing the overpass intersections with either a roundabout (better) or a cloverleaf interchange (even better).

A different problem that might be affecting you is that I've noticed the default game has very poor AI for selecting lanes on highways, causing traffic to back up in ways that aren't reasonable. The TM:PE mod has capabilities to fix that (I think it calls it "intelligent lane selection" or something like that).

[mbutton15]

I wouldn't suggest going down the TM:PE route. Instead, look to change your on/off ramps to the base game highway ramp. The reason for doing this is found in the 'Traffic 204 - Getting On the Highway ' section of this guide: https://steamcommunity.com/sharedfiles/filedetails/?id=522776740

You also mention traffic lights near you highway intersections. Whenever I do work around my highway exits I make sure there are no traffic lights close to the exit. The reason it to allow as much traffic to flow uninterrupted off the highway as possible.

For info, the 4 lane highway is not part of the base game, but is part of the Mass Transit DLC. I believe it's also available in the Network Extensions mod, which pre-dates the MAss Transit DLC.

[no one]

Thanks guys, this gives me some ideas on how to restructure my highway exits. Also thanks for posting the guide, it will be useful!

[Ferdiepip [NL]]

There are too many exits IMO. Try to make more secondary routes so not all the trucks have to use the highway.

[Lt. William L. Calley]

way to many exits and on ramps. when the AI come onto high way it will slow down many other AI cars. so by having this many exits and on ramps this is going to happen all along the highway

[Stealthy]

Also, don't build so many ramps. They disturb each others, especially if you don't got at least one, rather 2 node points in between as cars only change lanes in node points and no node means no lane change.

https://steamcommunity.com/sharedfiles/filedetails/?id=1582868192

[no one]

Okay, so I thought about how to tackle the issue and decided to try building an underground highway roundabout. For starters I put one access road bridging the highways and the roundabouts, one access road going from the roundabout back onto the main highway, once access road into/out of downtown, and one into/out of Downtown's adjacent district. After letting the traffic settle in it seems to actually work quite well. I'm still not sure how I'll tackle the industrial area but I have at least one idea on how to tackle that.

[Tatanka]

this doesnt help
https://steamcommunity.com/sharedfiles/filedetails/?id=1618745422

[alexUnder]

Please show up the results. I have same problems from time to time. And I am personally interested what exactly will work out for you.
PS. I did not know that too much ramps disturb each other

[scpool1986]

Originally posted by Alex Ros:

Please show up the results. I have same problems from time to time. And I am personally interested what exactly will work out for you.
PS. I did not know that too much ramps disturb each other

It reduces the merging distance between the on ramp and following off ramp. This is one of the few times the game follows a “real life” example. There’s an interchange about 10 miles from where I live where they have an on ramp actually dumping onto the freeway less than 500 feet before an off ramp, giving cars getting on or off almost no room to merge, resulting in 20-30 accidents a month in that one area with 90% of them either being “side swipe” (one vehicle hitting the side of another while merging) or where traffic exiting the freeway runs someone getting on the freeway off the road. The whole area was so poorly designed that if they were to fix it they’d have to give up on having an on ramp at that location. In the upper right side of the freeway I have circled is where the problem area is in the picture.

https://1drv.ms/u/s!Ar8wliG4u6V0irVGoZksESqqbiP55g

Loading a stretch of highway with on ramps and off ramps will lead to a lot of merging traffic and I’ve noticed that traffic in the game doesn’t really change lanes except for at nodes, otherwise it just stops and lets traffic back up behind it while it waits for the traffic to clear out of its original path.

[alexUnder]

+27 is what I see on your screenshot. Here in Russia its -13 (celcius)

[Stealthy]

Originally posted by Alex Ros:

Please show up the results. I have same problems from time to time. And I am personally interested what exactly will work out for you.
PS. I did not know that too much ramps disturb each other

They disturb in 2 ways.

As lane changes happens only in node points, limited amount of nodes pushes all lane changes to same place. If that even exists, which causes then its own issues as cars can't change lane where they would like to meaning alternative routes, too much traffic packing to one lane etc.

Another thing is that traffic tries to avoid the right lane around ramps, to give space for traffic leaving or joining the highway. Lot of ramps in line pushes traffic permanently to left lane and causes again erratic behaviour.

City up to say 150k people doesn't need more than 2 ramps, possibly 3.

[no one]

Update:

I intentionally did not save my last attempt at making an underground highway as it did not come out right and I bulldozed some stuff I didn't think I needed to at the time.

After a couple hours of playing with roads and trying to get the on/off exits to look symmetric, and checking/rezoning areas, I have finally gotten traffic flow up around 10% (give or take).

https://steamcommunity.com/sharedfiles/filedetails/?id=1619216573

As far as industry goes, I forgot to set some landfills/snowdumps I have right by the highway to empty before I started working on Downtown, so those will have to wait a bit.

I will update again if I can fix industrial traffic.