How to fix traffic congestion?

[rovas117 6]

I feel like I've got a good grip on the game now. I've managed to build skyscrapers and whatnot. What I'm struggling with now is the traffic and attracting $$$ sims.

Should I abandon the grid system for something else? 

How is commute time computed? Is it based on the DISTANCE the sim has to travel to their job? Or is it based on how many busy intersections they have to go through? 

I've been scouring Simtropolis for any in depth guide on how to deal with traffic/road layout and I can't seem to find any.

[TheMurderousCricket 5,042]

5 hours ago, rovas117 said:

I've been scouring Simtropolis for any in depth guide on how to deal with traffic/road layout and I can't seem to find any.

Have you tried the Prima Guide?

Around 30 chapters of solid (sometimes even too detailed) knowledge.

  Edited July 3, 2022 by Cyclone Boom  
Added Prima Guide link.

[rsc204 21,804]

Bear in mind the Prima guide doesn’t reflect the NAM traffic simulator’s changes.

One of the key benefits of the NAMs changes here is that you can pretty much build however you like, in game terms it will work. Sims are much more likely to find a job, even if they have to travel far to get to it. Provided of course your city/region has the right mix of zone types and jobs for the sims you have, things like education and wealth of sims matter here. Of course sims prefer shorter commutes and the simulator is designed to try and find the quickest route for all when determining which job each sim takes. So whilst a gridded one way system would probably be more efficient (quicker), it’s still very possible to build roads in a much more free-form manner without breaking anything. 

[CorinaMarie 29,556]

4 hours ago, rovas117 said:

How is commute time computed?

You might find this interesting: Tutorial:Understanding the Traffic Simulator

[rovas117 6]

Can someone help me understand how to properly design and layout my city?

I'm like following the proper rules of road hierarchy but it seems that my city still has filled to the brim with congestion. Mind you, this is a fresh new city and there's only one highway connection entering it. These like 15 minutes in thus far--development is fast because the demands are already super high from other cities in the region. I

What should I do? Can anyone point me to tutorials on how to properly design? The grid layout isn't working out either and commute time is just super high.

[matias93 7,535]

@rovas117

I would say that your main problem here is the lack of redundancy: each of those sectors is currently connected to the others by a single road, so no matter the capacities of the other networks, you are poised to get a bottleneck on that intersections. The same problem replicates at lesser scale on the other intersections, because for each residential or industrial lot that is sending sims or cargo elsewhere, there is a single viable route.

I will go on a limb and say that you took too strong of a concept of road hierarchy. The point of road hierarchy is to allow different travel strategies by road capacity, but always allowing the commuters (or the simulation, in this case) to choose freely the most efficient route. Here, you aren't giving the simulation any chance to choose based on efficiency, but forcing a single option for everyone. Certainly, some of your sims would use the routes you built anyway, because for their specific positions and preferences, it is the most efficient one, but not all, and with this design, you are making all the ones that would prefer different routes to congest the only available one.

If you want, you could experiment with this and try to continue the grid in a way that the simulation gets alternatives, but keeping the road hierarchy intact: in your scheme, roads can intersect with both streets and avenues, but streets and avenues cannot directly, so you could extend the avenues to intersect once again, and connect the roads of each section among them. That should ease congestion significantly.

Using your image as reference, this is a possible option: streets are in white, roads in yellow and avenues in orange.

[rovas117 6]

Alright. I'm going to try that strategy.

The issue I have with that was that I wanted to limit the amount of intersections I have, thus limiting problems with traffic. Is it possible for me to see your city so I can copy and learn from your design?

[CorinaMarie 29,556]

@rovas117

I've split the traffic congestion part of your Quick Question posts into their own topic so it'll be self contained.

Are you using NAM? That helps a lot and parts of the Traffic Simulator can be adjusted with the TSCT. I'm personally not keen on dealing with congestion so I've used the TSCT to tweak my settings way above both the Maxis and NAM defaults.

Here's how mine looks:

[matias93 7,535]

9 hours ago, rovas117 said:

Alright. I'm going to try that strategy.

The issue I have with that was that I wanted to limit the amount of intersections I have, thus limiting problems with traffic. Is it possible for me to see your city so I can copy and learn from your design?

The congestion you are seeing from intersections is normal, just cars, trucks and buses lining before a traffic light. Obviously, it will be heavier if the rest of the road is more congested too, but overall is not an issue, just the NAM traffic simulator working as intended.

Here is an example of one of my cities, which showcases the road hierarchy applied in a fairly typical way: in an orthogonal grid. The streets are most of the networking and collect local traffic, conducting it into the roads, then avenues and boulevards, and eventually, to the mass transit stations.

The way on which you can direct the traffic to follow the hierarchy is by controlling the zoning density and the position of mass transit stations. Note that I'm only zoning commercial and high density residential on roads and avenues, not on streets, to avoid overloading them, and to promote sims to travel to the biggest networks for work. Also, note how I didn't put bus stops on streets, but only on roads and avenues: I want buses to only go through roads and avenues, and sims to walk a couple of blocks from their house to the nearest bus stop, instead of taking the bus directly in front of their house. For rail networks this is even more marked: this site is a big intersection between a rail line and a subway line, but there aren't similar parallel lines for at least half a kilometre away, because they are the top of the transit hierarchy and are very expensive to build and run: sims should arrive to them by taking a bus first.

Here is a more didactic example, with the next train station on the same line, but now showing congestion levels. Note how also intersections and the tiles before intersections are the most congested parts of my networks: is the same principle at work. As you can see, the main roads and avenues are more loaded, while the closest streets are somewhat quaint: that's how road hierarchy looks in practice: you can be at a few blocks from a huge train station, but your local street is mostly silent and has barely any cars going through (I can testify this by experience, because I live at 3 blocks from a huge subway combination in crossing avenues, but here you can only hear birds and dogs).

Now, check this data views for the same city:

1. Pedestrians

2. Cars, buses and trucks

3. Buses only

Note how the road hierarchy shows: pedestrians use all streets, roads and avenues almost indistinctively, because walking is the main means to arrive to a transit stop. Road traffic is a bit more selective, concentrating on the main roads but still using some streets when located conveniently. Buses, by effect of only having their stops on the main roads and avenues, are only used on them.

[rovas117 6]

9 hours ago, matias93 said:

The way on which you can direct the traffic to follow the hierarchy is by controlling the zoning density and the position of mass transit stations. Note that I'm only zoning commercial and high density residential on roads and avenues, not on streets, to avoid overloading them, and to promote sims to travel to the biggest networks for work. Also, note how I didn't put bus stops on streets, but only on roads and avenues: I want buses to only go through roads and avenues, and sims to walk a couple of blocks from their house to the nearest bus stop, instead of taking the bus directly in front of their house. For rail networks this is even more marked: this site is a big intersection between a rail line and a subway line, but there aren't similar parallel lines for

Thank you so much! 

This is exactly what I need. I never figured to do that. I guess I never really put that much thought into the game on how to zone properly. I just like having numbers go up so I ended up zoning everything into medium-high density when I could, not really understanding that it'll overload the streets.

With that said, I'd like to know: how far along should bus stops be placed then? I keep trying to find this number and everyone gives me different answers.

I've been wanting to know, how far should transit stops be spaced out from one another? Like how far are Sims willing to walk?

[rovas117 6]

12 hours ago, CorinaMarie said:

@rovas117

I've split the traffic congestion part of your Quick Question posts into their own topic so it'll be self contained.

Are you using NAM? That helps a lot and parts of the Traffic Simulator can be adjusted with the TSCT. I'm personally not keen on dealing with congestion so I've used the TSCT to tweak my settings way above both the Maxis and NAM defaults.

Here's how mine looks:

Yes, I do have NAM and I will be copying these settings to see how it goes. X3

[matias93 7,535]

It depends on how your traffic simulator is configured, but I use this as an easy rule: given square blocks of 6 game tiles, you need a bus stop each 2 blocks, and a rail-based transit station each 5 blocks on their length. Those distances might be reduced on the city centre, where you have more density, and extended on the suburbs, where less density and more car-oriented designs might prevail.

In any case, sims do walk to get to their jobs, sometimes quite long distances, but 3 or 4 blocks is a reasonable expectation of walking distance. Consider, too, that distances in the game are ultimately measured orthogonally, so you should count distances as south-north and west-east displacements, not as a straight radius around a given point.

[rovas117 6]

4 hours ago, matias93 said:

It depends on how your traffic simulator is configured, but I use this as an easy rule: given square blocks of 6 game tiles, you need a bus stop each 2 blocks, and a rail-based transit station each 5 blocks on their length. Those distances might be reduced on the city centre, where you have more density, and extended on the suburbs, where less density and more car-oriented designs might prevail.

Is this the type of design you mean?

A bus stop every 2 blocks and a train station every 5 blocks. I'm assuming that you can only do this grid two layers deep like this because the people in the middle would opt to use a car if they were any farther from the bus stops, right?

[rovas117 6]

18 hours ago, CorinaMarie said:

@rovas117

I've split the traffic congestion part of your Quick Question posts into their own topic so it'll be self contained.

Are you using NAM? That helps a lot and parts of the Traffic Simulator can be adjusted with the TSCT. I'm personally not keen on dealing with congestion so I've used the TSCT to tweak my settings way above both the Maxis and NAM defaults.

Here's how mine looks:

I've tested these settings out and it almost feels like cheating given that I'm actually making a profit out of using public transport. I love the fact that everyone is using mass transit but the income I generate is insane. XD

[Lucario Boricua 7,026]

Let's be fair. This rule @matias93 is recommending is mainly based of the old habits from traffic simulators prior to the creation of Traffic Simulator Z (the standard and only NAM traffic simulator family for the last 13 years or so). Back then, the pathfinding was very much not optimized and the resulting trips would be overwhelmingly direct, mostly ignoring routes which prioritize less direct but faster routes. With Sim Z, you could double the spacings you were recommended and still get a significant level of mass transit usage, albeit with a lower share of transit use associated with increased spacing. This spacing, while traditional and easy to remember, will lead to a very high transit use, which is realistic for very dense cities with robust transit services. Otherwise, it may be excessive.

Keep in mind as well that the traffic simulator can be tweaked through the Traffic Simulator Configuration Tool (provided as part of the NAM download package) by changing the Mass Transit Usage strategy values, if you feel the transit use provided by the default configuration does not match your desired operation. You can set up 9 values, corresponding to a 3x3 array of resident wealth level (R§, R§§, R§§§) and commute strategy (car preference, mass transit/pedestrian preference, faster mode preference). Perhaps the most powerful of these values are those corresponding to the faster mode preference. You can make your sims highly responsive to the transit supply and quality if you increase the share of sims of each wealth level whose use the faster mode preference. Or, if you clearly know you prefer an overwhelmingly high or low share of the population using a particular travel type, increase the car or mass transit trip preference values, this will make the sims commute more predictably. Make sure each wealth level's values add up to 100.

 

[CorinaMarie 29,556]

4 hours ago, rovas117 said:

I've tested these settings out and it almost feels like cheating given that I'm actually making a profit out of using public transport.

Oh yes, indeed! It is a cheat the way I do it.   My settings show the extreme works perfectly and from there you can tweak downward for what feels right to you.

For me personally, not having traffic issues allows me to focus on all the parts of the game I enjoy.

[matias93 7,535]

13 hours ago, rovas117 said:

Is this the type of design you mean?

A bus stop every 2 blocks and a train station every 5 blocks. I'm assuming that you can only do this grid two layers deep like this because the people in the middle would opt to use a car if they were any farther from the bus stops, right?

That's how I tend to do it, but as Luc says, a correctly tuned simulator should be more lenient. I kept with those old references because I like my cities dense and transit-based.

In any case, this is a general model, not something you should necessarily have to repeat continuously in all your cities. Having diagonals and curves and whatnot is perfectly possible if the underlying grid sticks loosely to the same principles, scaled at need.

[TheMurderousCricket 5,042]

On 4.07.2022 at 1:38 PM, CorinaMarie said:

I'm personally not keen on dealing with congestion so I've used the TSCT to tweak my settings way above both the Maxis and NAM defaults.

I basically feel the same way about traffic, but since I'm a bit more ambitious than Cori I like to deal with some challenges while playing, I use the "High" preset available in NAM, which, as far as I can see, is significantly lower than the values Cori uses.

I have several policies that I usually use when trying to deal with high traffic in the city:

1. Building mass transit stations close to residential zones in any areas that are frequented by cars. First, I use the route query tool to identify the roads where cars are dominant form of transportation. Then, I try to reach these areas with some form of public transport. When the car-driving Sims notice that they pass a public transport stop on their way to work, they are likely to switch to that transportation mean the next day. This, in turn, reduces the number of cars coming from this-such street and the traffic on any roads across the city that these cars have previously used.

2. Changing the percentage of Sims using public transport through TSCT, just like @Lucario Boricua has correctly suggested. This is especially useful in any settings when you are after a real-life-ish regions like Europe which traditionally enjoy high ridership numbers on their public transport.

3. When a piece of network is almost at full capacity or beyond capacity, I just upgrade it to a higher-capacity network. Street becomes road. Road becomes a two-lane road. Two-lane road becomes a three-lane road. Three-lane road becomes a vanilla avenue. Vanilla avenue becomes a three-lane avenue, etc., etc., etc. I'm not sure if upgrading a standard intersection to a roundabout improves anything... but I guess it should! At least it does work IRL.

4. I make overpasses or underpasses on busy intersections. Careful though - you don't want to deny the drivers an opportunity to turn left or right in a place where an intersection have previously existed. You need to offer a road turn before your commuters actually enter a viaduct. Otherwise they'll be stunt-jumping off of the overpass to get to the road they need.   You can also bypass the intersections by converting them to tunnels. Note that tunnels and overpasses work best if you have high numbers of commuters who just drive straight through the intersection from perpendicular directions (N/S vs. W/E). If you notice that many commuters actually take a left or right turn on an intersection, it's probably better to leave the intersection as it is...

5. I never hesitate to bulldoze an area or a zone if I see that running a road through a given piece of land could be a good option to deescalate traffic problems. I just lay down the road and demolish what has to be demolished. Many players consider already developed zones as sacrosanct - they never bulldoze or redevelop them in any way. Personally, I prefer to sacrifice some of the buildings rather than watch my city suffer from dense traffic and clogged intersections. Divide et impera! Of course, any demolitions should be reasonable as well... If you have a group of single-family houses in your way, it's probably no big deal to remove them. If, however, laying down a new high-capacity route involves destroying three CO$$$ skyscrapers that you have worked very hard at developing, then you should probably find another spot for your new road...

 

[matias93 7,535]

On 7/7/2022 at 9:29 AM, TheMurderousCricket said:

I'm not sure if upgrading a standard intersection to a roundabout improves anything... but I guess it should! At least it does work IRL.

Depends on the roundabout, but in general, the bigger the intersection's footprint, the lower the congestion in it, unless all the traffic moves in a single direction, in which case it's about the same.

With avenue roundabouts, there's an issue with how they were modded originally, that makes of them somewhat of a bottleneck. Luc is working on a somewhat quick fix to it, and considering potential plans for expanding the roundabout set with newer curved pieces, but that's all on the drawing board yet.