NAM Traffic Simulator and Data View Help

[z]

Whenever I've changed simulators in established cities (especially large ones), it has taken several game years to 'balance' out and get the paths correct. Might try to let it run to see if it helps...

This is well-known behavior, intentionally built into the underlying traffic simulator by Maxis.  In some places this is referred to as anti-herding behavior.  The idea is that if you change simulators, or simply make changes to crtain key parameters in your simulator, a lot of Sims need to change their routes to work.  Many cities are laid out so that they would all flock to a few "best" routes.  Congestion that would result from this is not considered when the routes are chosen; it is only considered after it has occurred, at the next running of the simulator.  The next time the simulator ran, it would notice that these "best" routes were now all congested, and it would redistribute traffic to second-best routes.  But the next time the simulator ran after that, these next-best routes may be congested, or in any case, the original "best" routes would no longer be congested, and the simulator would reroute the Sims back to them.  So there would be massive changing of routes back and forth each time the simulator ran, with no equilibrium being reached (at least not for a very long time), and the whole behavior would seem very unrealistic.

Instead, the traffic simulator has the anti-herding behavior implemented.  What this does is to limit the increase in traffic on a particular route during a given run of the traffic simulator; this limit appears to be raised about once a year.  Under normal circumstances, it will take about five years for the traffic distribution to reach equilibrium.  You can see this as a stair-step pattern on the Traffic Volume Graph.

Meanwhile, you will tend to see traffic drop off sharply in the Traffic Volume Graph about a year after switching traffic simulators, just before the stair-step pattern begins.  Traffic actually isn't dropping off at all; it's just that the routes of the Sims that are affected by this change are indeterminate until the equilibrium is reached.  So they're still getting to work, and you need not worry about them; it's just that their routes and modes of transportation are undefined.  It's a little bit like the Sim equivalent of the superposition of states in quantum mechanics, where a particle's position is undefined until the collapse of the wave function.  I'm sure that's what Maxis had in mind.   

[CaptCity]

Z...

You know you've just explained and connected every type of odd behavior I've ever seen concerning the traffic patterns of those rascally Sims - thanks! (Please don't tell me it's been posted somewhere else - I'd be totally embarrassed...   )

...the superposition of states in quantum mechanics, where a particle's position is undefined until the collapse of the wave function.

Oh my, I actually understand that... Guess those those four years of schooling weren't a waste after all... 

I'm sure that's what Maxis had in mind.   

Don't know about that one... 

[nataus]

Hello! I have a little problem. Since I installed the new NAM (June 2009), I've been getting black holes showing the game's background on some lots each time I was entering the subway building view (that's just an example picture):

You can see it under the windmill or whatever it's called in english.
Then, after hours and hours of fighting with it, reading and rereading all the NAM readmes, I discovered that deleting the "volume data view" file solves the problem.
I've been trying with different volume data view files, according to different traffic simulators installed at each time, of course. And always the same thing happened.
I don't believe there was a conflict with other plugins, because I also tried this with NAM only in the plugins folder.
In the installer, there's no option "installing or not installing" the volume data view file, so I want to ask how important it is. Does it have any hidden function in the game? Is it important for the proper functionality of NAM? Simply: can it be safely removed? I want to keep the NAM, I've been using it for years and I can't live without it, but I don't want it to harm my game Will it still work without volume data view file?

[z]

Hello! I have a little problem. Since I installed the new NAM (June 2009), I've been getting black holes showing the game's background on some lots each time I was entering the subway building view (that's just an example picture):

Yes, the new NAM introduced a new Subway Building View, and these "black holes," as you call them, occasionally show up in this view; they appear to be a game bug.  As you notice, they disappear when you leave this view.

I discovered that deleting the "volume data view" file solves the problem.

Yes, the new Subway Building View is embedded in the volume data views.

I've been trying with different volume data view files, according to different traffic simulators installed at each time, of course. And always the same thing happened.
I don't believe there was a conflict with other plugins, because I also tried this with NAM only in the plugins folder.
In the installer, there's no option "installing or not installing" the volume data view file, so I want to ask how important it is. Does it have any hidden function in the game? Is it important for the proper functionality of NAM? Simply: can it be safely removed? I want to keep the NAM, I've been using it for years and I can't live without it, but I don't want it to harm my game Will it still work without volume data view file?

There is no conflict with other plugins, and the rest of the NAM will work without the new volume data views.  However, the old ones are essentially useless with the current traffic simulators, which is why the new ones were introduced.  Also, the new Subway Building view gets around the longstanding problem that in the standard Subway Building view, even moderately tall buildings blocked the view of the streets enough that it was quite difficult to accurately plop new subway stations.  Removing the volume data views brings this problem back.

So to summarize, the purpose of the new volume data views is to see the volume of the different types of traffic in a realistic way (using the Traffic Volume Data View), to be able to build subway stations without having your networks hidden by buildings, and to be able to see your subway volume when building subways.  Removing the volume data views disables all of these features.  However, the rest of the NAM will still work fine.

[nataus]

OK,
Thank you for dispelling my doubts. It's good to know that you know about this problem, I was a little worried, because I coudn't find the information anywhere.
And thank you for waht you do to help us, simple players, to make the game even better

[gtaki]

hi z

I have mentioned this effect shown in nataus' pic...
And it seems it takes longer loading time when switching from subway building view to normal view.

is this normal ?

[z]

I have mentioned this effect shown in nataus' pic...

As I mentioned, it seems to be a game bug.  Specifically, it seems to be caused by displaying the Zones view without buildings but with props.  The props do seem to be very helpful for orientation, though, and people like them; furthermore, they make it easy to identify transit stations (which in cases such as RTMT, consist entirely of props).

And it seems it takes longer loading time when switching from subway building view to normal view.

is this normal ?

I haven't seen this, nor heard this before.  But it's easy to guess what's happening here, and there's an easy fix.  The new Subway Building view is actually based on the Zones view instead of the Subway view.  (You may have noticed that it's almost identical to the new Zones view.)  I would imagine that you are used to waiting a long time to return from the Zones view to the normal view, and I would also guess that you have a lot of plugins.  The fix is simple:  datpack your plugins.  (Leave out frequently updated packages such as NAM and RTMT.)  Not only will SC4 start up faster, but returning from Zones-based views to the normal view will once again proceed quickly as well.

[doorknob60]

In my cities the Sims use the Subway TOO much. It's getting out of hand recently. My previously full highways (9000 sims) are now deserted (700 sims) and I didn't really change anything in the city. Looking at the traffic volume map, it looks like 80% of the sims use the subway. That's not all that realistic. The two cities I'm noticing this in is a large tile with ~1,180,000 sims and subways/GLR with RTMT on all roads and avenues for the most part, and the other one is a more suburban large tile with ~200,000ish sims (don't remember) with also the same style of Subway placement. This didn't happen before, what simulator/difficulty would you recommend. Also, is it a bad idea to use so much subways?

This is the smaller city (actually 131,000). The red looking line is just the exact same number of pedestrians and subways.



The bigger city is the same thing with just 10x more people and not quite as bad, and also they actually use buses sometimes in that one (they stopped using buses in the small one). I use high, should I switch to medium or low maybe? I'll get pics of the big city too.

All the road congestion on the west side is from T-RAM, I use T-RAM over there and Subways on the east side and in the middle.

[z]

As Chris101 pointed out at ST, the Sims are using the subways simply because they're faster.  First, keep in mind that the game's population figures have been determined to be many times higher than they would be in an equivalent real city - in many cases, they're 10 times as high, according to a reliable study here.  If you look at your smaller city, you'll see that it looks like it has a population of well under 100,000.  Normally, cities that size don't have any subway lines at all, although they often have a main highway or two running through them.  But your little city has a subway density greater than that of Manhattan.  No wonder the Sims use the subways so much!  Now it's true that in the past, you often had to put an unrealistically large number of subways in your cities to get them to function properly at all - I noticed this going all the way back to SC3K.  But Simulator Z makes this unnecessary.  If you build a city with a realistic distribution of highways, subways, and other mass transit, you'll get a realistic distribution of travelers on these networks, and the Sims will be able to get to their jobs without problems.  But if you put in lots of subways, the Sims will use them - they're much faster for getting to work than roads.

Also, subways do come at a cost - literally.  For technical reasons, it's difficult to raise the cost of a subway tile without creating dependencies with too many other things in the game.  But projects like subways aren't paid for all at once, anyway.  So what I did was to multiply the monthly cost of subways by a factor of six.  (This is still way too small, but raising the cost much higher than that would break too many existing cities.)  This extra monthly cost can be considered payment on interest-only bonds that were issued to pay for the subways.  And now, subway maintenance cost is no longer inconsequential.

You have a couple of options here.  You ask, "Is it a bad idea to use so much subways?", and I have essentially answered "Yes" to that question.  You can demolish a lot of the subway lines, which will help your budget a lot, and it will also cause usage of all other forms of transportation (including buses) to increase.  Or you could move to a lower capacity simulator.  To get a real difference, you would need to move to the Low capacity.  At least in your large city, your subways would start to get congested, their speed would drop, and at least some Sims would move to other forms of transportation.  A fully congested subway (one that shows up red) has a speed just a bit less than an uncongested road, so there's a potential for quite a shift by doing this.

[doorknob60]

Thanks for the detailed reply, z I'll mess around with it...as soon as I get a new motherboard

[woodb3kmaster]

I'm considering switching from the easy version of Simulator A to Simulator Z, and I have a couple of questions. First, for a city that has a lot of mass transit in place (which BTW isn't getting used all that much), which version of Simulator Z would you recommend that I switch to, at least initially? Second, what kind of changes should I expect to see in traffic volume during the five-or-so years that it will take the simulator to reach a new equilibirium? I know that Simulator A increases the distances Sims are willing to walk/drive/whatever, and it seems from reading your earlier replies that Simulator Z effetively eliminates these limits altogether, if I'm understanding your posts correctly. Will this change have a noticeable impact on the appearance of the nefarious no-job zots, which seem to come and go in certain parts of my cities for no apparent reason, and if so, in what way? Apologies if you've answered similar questions on previous pages of this thread.

[z]

If you have a lot of mass transit, and your city isn't huge, I'd say try the Low simulator first.  You can always move up to a higher capacity simulator if you need it.  Of course you could just start out with High or Ultra; it all depends on how much realism you want in your city's traffic congestion.

You will find that under Simulator Z, your mass transit gets used a lot more than under Simulator A.  It almost appears that your Sims are getting smarter, which is effectively what's happening.  Most, if not all, of the no-job zots should disappear, assuming that you have enough jobs to be filled.

As for the behavior of the traffic volume during the first five years after switching traffic simulators, please see this post for an in-depth explanation of what happens.

[woodb3kmaster]

Thanks! My central city is pretty big, with about 670K residents and 425K jobs, so perhaps Medium would work better for me than Low? If that doesn't result in as much of an increase in mass transit usage as I hope for, I'll try switching to Low.

[z]

A lot of this depends on how much rapid transit you have; this is essentially rail lines, including subway.  With enough subway lines, you can run cities with several million Sims quite well with the Low simulator.  On the other hand, if your mass transit is mainly buses, you may need to use Medium, or even High.  Whatever your choice, though, you should see your rapid transit usage increase significantly.

[GoaSkin]

Hello,

is there a way to create a traffic simulator that makes commuting to neighbor-cities more attractive even if the ways are very long? In some rural areas of my landscape, I use big cities just to build a town that covers a small part of the area only - all the other parts of it is just used as functional biosphere. In the result there is allmost no commute to neighbor cities because the streets are many kilometers long without any house.

[z]

s there a way to create a traffic simulator that makes commuting to neighbor-cities more attractive even if the ways are very long?

Not without changing the source code, which we can't do.

[GoaSkin]

Do you need some informations from the source code? I can examine it but not everything is easy to understand.

[z]

It wouldn't help, as it's not legal for us to change it.

But how do you have access to the SC4 source code?

[SC4BOY]

from other thread for reference

...As you guessed, the change in bus behavior is a traffic simulator issue, and occurs only in Simulator Z, which I gather you're using. ..explanation..

Basically, the traffic simulator works much better if you're able to let it count buses as contributing to traffic.

.. too much congestion using Simulator Z, there are two ways to alleviate it: 

[..a..] a higher capacity version of the simulator
[..b..]build [more] subways.  In any case, it should be possible to reduce congestion to any level you like.

..further questions about Simulator Z, I'd be happy to answer them, but you're right, they would belong in another thread, specifically [..this current thread..]

hmm.. Well with this approach why use buses at all? They just become cars. I don't have much problem moving to higher capacity simulators.. just seems rather a stretch for the solution.. well I guess the real rub is that buses look like cars.. just isn't logical.. regardless of the capacity simulators. With higher capacity simulators, then the cars become insignificant.. but I'll play with it a bit to see what I think... I mean introducing subways into cities of 30-70k seems a bit far-reaching for solutions. This approach basically makes cars=buses and subways="new buses" that don't have to travel roads. Do you have a link to your detail analysis on ST? Thanks.

Do you know if "customer count" for commerce counts subways, buses, cars, pedestrians, etc equally? I assume not subways since they are undergound, but perhaps as they pass through stations, etc. Do trucks play a role at all? ie are they just another "customer"? The region I'm currently playing I specifically set up for two reasons.. to check out CAM and to try out a "no commuter loop" network design that forces as much as possible traffic to go through commerce centers rather than just wandering around the periphery. I don't spend a lot of time on it, but its fun for playing around..

Glad to see you've become deeply involved in the simulations.. always nice to see folk discovering or re-examining the "guts" of the game.

[z]

The reason for having buses is to simulate the role of buses in a real city.  Like everything else in SC4, this is oversimplified, and so buses don't behave like real buses.  Then again, no vehicles do.  The vehicles you see in SC4 - the automata - generally don't reflect at all what's really happening.  Just scratch the surface a tiny bit, and you discover the following:

• Vehicles don't stop at stoplights, stations, or anywhere except their terminating stations.
• Sims never have to wait for vehicles.
• There actually aren't any vehicles anyway.
• Sims don't commute to and from work every day.
• There isn't any traffic.
• There are no vehicular accidents.

This is just the beginning.  You can find an explanation of these points in this post in the thread "TE Lots, Transit Switches, and You," which gets rather deep into how the traffic simulator actually works.  (The article at ST actually doesn't contain any other information relevant to this discussion.)  We are limited by how the underlying traffic simulator is implemented, which makes it impossible to implement buses (or any other vehicle) realistically.  Experiments have shown that Simulator Z comes the closest of all the traffic simulators; you can see some of the most crucial experiments in this post in the Traffic Simulator Z Development thread.

Sims will still use buses, which are slower than cars (as in real life) because the traffic simulator says that a certain proportion of them should where possible, and this proportion varies by wealth level.

What it comes down to is that Simulator Z tries to make the best traffic simulation possible given the limitations of the underlying simulation engine.  Although I think I've got the major issues taken care of at this point, there's always room for improvement; I'm currently looking into making the simulator make Sims wait for buses, trains, etc., instead of having these vehicles appear immediately.  This should result in an even more accurate traffic distribution.  In the next few weeks, I'll be releasing a trial version of this simulator; if you'd like to try it out, keep an eye on the development thread I mentioned above.

As for customer count, all travel types play an equal role, except for trucks and freight trains, which carry only freight.  The freight plays an important part in the game, but it just doesn't contribute to customer count.