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NAM Traffic Simulator Development and Theory

Started by z, August 02, 2008, 05:07:50 PM

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z

Quote from: redraider147 on August 26, 2008, 02:43:36 PM
ok so lets bring some of my test results to the public....

1. one interesting side effect that i've been able to reproduce over and over again is that my game and cities load twice as fast (if not faster) than before when i was using the NAM traffic simulators...curious...it was the only thing changed.

I have no idea why this is happening.  There is nothing in any traffic simulator that I know of that would cause this, so I can't take credit for it.

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2. while commute time dropped only slightly over NAM simulator AP, traffic volume decreased, congestion decreased, and population increased. how if all my transportation volume categories decreased is my population rising?

3. my population is increasing, but the amount of abandoned buildings is increasing (all due to commute time)...weird...and commute times are decreasing from before...

This all makes sense if you understand how the game works.  Commute time decreases because I'm using a more efficient pathfinding engine than Simulators A or B.  But you have to go by relative commute times, because the absolute numbers aren't scaled correctly in all the simulators.  I'll send you a version that has commute times scaled correctly in actual Sim minutes for this simulator.

Congestion is greatly decreased because network capacities are larger, and pathfinding is better.  Add all of these things together, and the result is less traffic (which to some extent, further reduces congestion).  The Sims are traveling shorter and often faster routes, and spending less time on them.  Since there's less traffic, there's less traffic noise and less pollution, both of which increase residential desirability.  So your population starts increasing.  The system has extra capacity built into it, so you still have less traffic than you started with.  But now you have more Sims.  Where are they going to work?  Max commute time is set very high, so your Sims can get to work almost anywhere.  So there are two possibilities I know about that could explain your building abandonment:  1) You don't have enough jobs for your larger population, so you'll run out the commute time clock, no matter how high it's set, before they find jobs, because there are no more jobs to find.  Or 2) You may have hit the CAM Demand Bug, which will produce the same results.  This bug is being fixed in CAM 2.0, which should be entering beta testing soon.

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4. one curious thing i noticed is that my sims take the freeway to work, but not home...ramps are exactly the same on both sides as i use the feeder road system. they all want to take avenues home from work...

This is completely normal behavior for Sims.  As long as routes get them to or from work in similar amounts of time, they aren't too picky about which ones they take.

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5. is there a park and ride aspect that i might be missing? that seems like it should be my problem...it looks like what happened when i installed the AP simulator and hadn't placed parking garages and lots...

The version I sent you is not a Park and Ride version.  And to answer Brian's question, the AP simulator is Simulator A with Park and Ride enabled.

Quote from: The_Wind on August 26, 2008, 05:30:06 PM
hmmm this sounds very intresting, i hope i can see it realesed.

I assure you that at some point it will be released, either here, on the STEX, or both.

The_Wind

i have a question, what will this do for inter0tile commute times? in somecities while using simulator a or b i would have area's that would addandone dew to commute times, when my commute time was say around 60+ max. is this normal? or rare? And what would you simulator do for that?

b22rian

Quote from: z on August 26, 2008, 05:59:33 PM

2) You may have hit the CAM Demand Bug, which will produce the same results.  This bug is being fixed in CAM 2.0, which should be entering beta testing soon.



Z,
Ive seen you mention about this bug before.. Can you explain exactly what it involves, or direct me to a thread
which explains about it when your not too busy ..

Thanks Brian

z

#23
@b22rian: Who better to explain this bug than RippleJet himself?  You can read his explanation at http://sc4devotion.com/forums/index.php?topic=2488.msg159401#msg159401.  If you want the full context of the discussion, you need to start at the last post on the previous page.

Quote from: The_Wind on August 26, 2008, 07:01:36 PM
i have a question, what will this do for inter0tile commute times? in somecities while using simulator a or b i would have area's that would addandone dew to commute times, when my commute time was say around 60+ max. is this normal? or rare? And what would you simulator do for that?

One of the main design goals of my simulator was to improve intercity commuting.  Simulators A and B simply don't have a high enough max commute time to support large scale intercity commuting.  As for your commute time number, the number you see in the graph is in itself not too meaningful, because it's not scaled correctly in Simulators A and B.  Using the Maxis scale of 64 squares = 1 km, the maximum one-way commute time in these two simulators is 8.5 and 12 minutes, respectively.  That's large enough to accomplish the commute goals jplumbley describes, but for longer commutes, it's just not sufficient.  My simulator supports much longer commute times, which leads to far less abandonment due to commute time.  Theoretically, it should eliminate abandonment due to commute time if the rest of your city and region is played properly (not an easy task), but the aforementioned CAM Demand Bug will have to be fixed before I can see if that actually happens.  In the mean time, make sure you have enough jobs of the proper type for your Sims.

Whether abandonment is normal or rare depends on many things.  It is quite possible to use Simulators A or B on a large tile and have little or no abandonment; xxdita has a thriving city of eight million Sims using one of these simulators.  But you have to be careful about the way you plan and lay out your city.

redraider147

The CAM bug appears to be the problem...this is my first region with it and this is the largest city i'm having problems in. if this is the case, to accurately see the affects of the simulator, one must remove the mod, or wait for it to be fixed....i'm not about to remove it as i have many buildings in my city from the CAM. plus the face that i am trying for a simlympic bid with a city that wasn't created for a city journal, and i seem to see my city developing naturally the way i was hoping it would, i likely will wait til v2.0 is released.

z

I agree - I certainly wouldn't recommend removing CAM.  I think what's happened to you is very similar to what happened to me - namely, this simulator improves traffic flow to the point where the CAM demand bug becomes a much more significant obstacle to growth.  For this reason, I'm going to hold off any general release until this bug is fixed, which shouldn't be too long.  A working fix has actually been demonstrated, and it's just a question of getting it automated and wrapped into the CAM 2.0 release.  Part of this may actually be done already.  I'll keep everyone informed as to progress in this area.

b22rian

thanks Z,

for providing me with the thread of the cam demand bug..
I havent noticed any problems with my city (residential pop is close to 1 million now..)
But by examining my city i see why I havent..its because i have about double the job supply compared
to the work force in my city.. I always play having a large commercial job supply because i like having
a dense commercial district with lots of high rises in my cities..But I had a look at my CRF version 2 and
currently demand for R $$$ is actually higher than either R $$ or R $... Although compared to your example
city you had in the cam thread i have a little less % of the population being R $$$ compared to what you
showed maybe about 8- 9 % compared to the 10 %..you showed.. My current tax rate for R $$$ is actually
higher than the other 2.. R $$$ is 6.4 % compared to 5.5 % for both R $$ and R %.. which is interesting..
But the main reason i think I currently have such a high demand for R $$$ is the amount is huge CO $$$ and
CO %% high rises i have which is a lot !, thus a high work supply.. for R $$$ residents..

so I was just lucky, its really my style of play which compensates for the demand bug with Cam you found..
But I do understand your guys frustrations with it, because prolly you dont want so many job zones in your
city.. Especially you Z i understand because your trying to replicate Chicago as accurately as you can..
Hopefully as you said at least a beta release of cam 2.0 will come out soon..

Also sorry I'm drifting away from the subject matter of this thread which is supposed to be about your new
traffic sim.., But I think.. like you guys, best for me would be to start a new city with your new traffic sim , Z and
hopefully cam 2.0.. although it sounds like I may have to change my playing style a bit with the way i build too
much commercial zoning.. Although I think it would be interesting for testing purposes still at some point to use
your new traffic sim with my current city, and than we can make another useful comparison such as red raider
posted..?  Since my largest city is quite large and uses a wide range of transport networks..

My apologies, Brian

Diggis

Quote from: z on August 26, 2008, 08:49:30 PM
One of the main design goals of my simulator was to improve intercity commuting.  Simulators A and B simply don't have a high enough max commute time to support large scale intercity commuting.  As for your commute time number, the number you see in the graph is in itself not too meaningful, because it's not scaled correctly in Simulators A and B.  Using the Maxis scale of 64 squares = 1 km, the maximum one-way commute time in these two simulators is 8.5 and 12 minutes, respectively.  That's large enough to accomplish the commute goals jplumbley describes, but for longer commutes, it's just not sufficient.  My simulator supports much longer commute times, which leads to far less abandonment due to commute time. 

I may be wrong, but as I understand it once the commuters reach a city limit their commute is reset.  This is due to the cities being autonomous and one not checking another cities files.  All they do is see X commuters coming in from city A, but not how far they have travelled before getting to the city border.  If they find a job closer to their point of entry than another city border then they'll stop there.  If the commute time is long enough to cross one full city, then won't it be enough to cross more?   ()what()

Shadow Assassin

QuoteIf the commute time is long enough to cross one full city, then won't it be enough to cross more?

It depends on what's going on in that city tile...
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z

Quote from: Diggis on August 27, 2008, 04:04:25 AM
I may be wrong, but as I understand it once the commuters reach a city limit their commute is reset.  This is due to the cities being autonomous and one not checking another cities files.  All they do is see X commuters coming in from city A, but not how far they have travelled before getting to the city border.  If they find a job closer to their point of entry than another city border then they'll stop there.

This part is definitely true.

QuoteIf the commute time is long enough to cross one full city, then won't it be enough to cross more?   ()what()

Here's where things get interesting.  It appears that this is true, but only in cities beyond their original city.  Through numerous experiments I have found that if Sims start out in one city, their chances of being able to cross a border into an adjacent city are directly related to how far they'll be able to travel in that new city on their current network.  So, for example, as you raise the Commute Trip Max Time property in the simulator, you see more and more intercity traffic by rails (typically subways for me), which are the fastest form of transport.  (This assumes you have sufficient demand in your adjacent city.)  But cars still don't cross the border very often.  If you raise Commute Trip Max Time enough, cars start streaming across the border in large numbers as well.  So since I want to support intercity commuting, I've raised Commute Trip Max Time to this latter point, which is more than an order of magnitude higher than that used in Simulators A or B.

As to what happens to these Sims when they enter the second city, they definitely seem to have enough commute time to cross the whole city, and I've seen them enter a third city.  So from the data I have so far, it seems that if they have enough commute time to make that initial crossing, they should be able to continue traveling through cities until they find an appropriate job.

The_Wind

#30
hmmm thank you for awnsering, this simulator you are planning sounds very nice, hope for the best :thumbsup:
also i can be a tester if you need, seeing as im just starting up a new region.

z

#31
In an earlier post, I said I was going to hold off releasing any version of my traffic simulator until the CAM demand bug (exlplained above) had been fixed.  I have decided not to wait until then for three reasons:  1) The effect of the CAM demand bug is not that great; it's simply slightly more visible in this simulator than in others because of the increased maximum commute time.  But even in the worst cases, I find that that for large cities spanning multiple tiles, this simulator works better for me than Simulators A or B.  2) I've received reports back from my single tester, who has also encountered the CAM demand bug, but still prefers this traffic simulator to any other.  3) I keep getting numerous requests to release this simulator.

Finally, for many people the CAM demand bug will not be very visible, or will not be visible at all - especially if you don't use CAM!  So I have decided to release an alpha version of this simulator.  Although it is an alpha version, I have been running it for months on my system with no problems at all.  So there are no known bugs.

As I've mentioned in previous posts, this simulator uses values for many parameters that are very different from those in Simulators A and B.  The main criterion in picking these parameters was to make them as close to what is found in the real world as possible.  I have gone into detail about a number of these parameters in an earlier post; I will finish that post when I have more time.  (Right now, I'm working on getting the next version of RTMT finished; I'll have the necessary time when that's done.)  My tester says that he sees "a much more realistic traffic pattern" with this simulator; that is my experience as well.

Right now, there is only one version of this simulator; additional versions (as with the current simulators) will be available later in the development process.  This version should work fine in all sizes of cities.  It is completely compatible with NAM, CAM, RHW SAM, etc.  The simulator is compatible with most of the NWM roads, except for the TLA and OWR-5 roads.  These roads will still work; they will simply be very heavily congested in highly trafficked areas.  But NWM is not released yet; by the time it is, there will be a version of this simulator that works perfectly with all forms of NWM.

As this simulator uses high capacity networks, it requires high capacity mass transit stations for optimal performance.  I would recommend the current version of RTMT for this purpose.  When installing, I would recommend using the CAM capacity setting.  If you do this, then after the install, replace the Stations file with the identically-named file in the attached zip archive; it is specifically tuned to this simulator.  If you already have RTMT installed, you can still replace your Stations file with the one in the archive.

To install this simulator, first remove any other traffic simulator you are using, as well as any version of my Traffic Volume View.  Also remove the file NetworkAddonMod_Congestion_Data_View.dat if you have it installed.  Then extract the first two files in the archive into your Network Addon Mod folder.  You can switch to this simulator in an existing city or in a new city; it doesn't matter.  If you try it and don't like it, you can switch back to your old simulator.

As this is an alpha release, there is limited support available for it, largely due to my lack of time.  But comments in this thread are welcome, and I will answer those questions which seem to be most important.  So here it is - enjoy!

EDIT:  This version of the traffic simulator has been superseded.  You can get the current version here.

MassHelper

So can u list the capacity changes from this new traffic plugin???
SC4 Modders' Assistant and Adviser

z

Quote from: MassHelper on October 04, 2008, 03:47:57 PM
So can u list the capacity changes from this new traffic plugin???

A very reasonable question, indeed.  Network Traffic Capacity was the next section I was going to add to my post on implementation details, so I decided I might as well do it now.  You can find the section on Network Traffic Capacity at the bottom of this post.  The reason I am not just listing the numbers here is that they are not directly comparable to those of other traffic simulators, for reasons which I explain in the post.  So by reading the new section, you'll see all the numbers, but you'll also see the context in which they work.

MassHelper

Hey, Z thx for the notice....

Is the value for the cap in street 15K....??? I hope the 1,500 is not a typo... (That cap would be over in a day in the simulation)...
SC4 Modders' Assistant and Adviser

z

No, the 1,500 is not a typo.  This capacity is an eighth of the road capacity; in the original Maxis traffic simulator, streets were a tenth of road capacity, so this proportion is fairly close.  If you look at the difference between streets and roads in real cities, I think you'll see that this proportion is pretty reasonable.

MassHelper

Oops...

Anyway... Is this simulator compatible with Simulator A or B in Apr. 08 NAM???

;) Mass
SC4 Modders' Assistant and Adviser

MassHelper

So... wat's the final outcome???  :-[

Should I use Z's simulator add-on or keep on using Simulator A/B???

:) Mass
SC4 Modders' Assistant and Adviser

z

#38
Quote from: MassHelper on October 05, 2008, 10:38:36 AM
Anyway... Is this simulator compatible with Simulator A or B in Apr. 08 NAM???

;) Mass

If you take a city you've built with Simulator A or B and drop in this new simulator, everything should work fine.  If you continue building your city the way you had been with Simulator A or B, then you can switch back to that simulator at any time with no ill effects.  I have verified this through testing.  Is there anything else you mean by "compatible"?

z

Just to make things clear:  No one's talking about running multiple simulators at the same time.  My installation instructions specifically state that any other traffic simulators need to be removed first.  And at the top of my previous post, I use the word "switch" when addressing the compatibility issue.  I had assumed that MassHelper was talking about the ability to switch back and forth between simulators when he asked about compatibility.  If he (or anyone else) wants to run multiple traffic simulators simultaneously, obviously, you can't do it.