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April 29 Seminar Transcript

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(20:39:40) god_donut: Okay, so we all know traffic engineering in this game is entirely different than traffic engineering in SC4
(20:40:06) god_donut: not just because proper smooth curves and free-form roads are possible, but because the entire simulator has been re-written to be more life-like
(20:40:37) god_donut: but, as most players have found out, and as we're going to find out in this seminar, life-like is quite relative because the default simulator still has its shortcomings
(20:41:18) god_donut: however, even though the game has only been out for a little over a year, the community has built a suite of mods that, when used together, is essentially the equivilant of the NAM
(20:42:06) god_donut: before continuing, it is important to know what mods are used, and which mod does what
(20:43:29) god_donut: the most important mod that will be referenced is Traffic Manager: President Edition, found on the steam workshop - this mod provides a very wide range of features which allow for traffic management and engineering far beyond the scope we see now or will ever see possible with SC4.
(20:43:54) god_donut: but perhaps the best thing is that it takes the default traffic simulator, which is already an improvement over SC4, and builds on that
(20:43:56) Darvince: i have that one :D
(20:44:17) god_donut: there are other mods as well, I will have a list of them as well as links when the seminar is done
(20:45:02) god_donut: some of the features of this mod include setting timed traffic lights, speed limits, stop and yield signs, and restricting vehicles from accessing networks
(20:46:07) god_donut: these won't be covered in great detail, we'll instead be looking at the new simulator and how it functions, and how it can be utilized to solve traffic issues and create very realistic life-like city highway traffic
(20:46:34) god_donut: first, we'll look at the default simulator
(20:47:19) god_donut: when comparing SC4 traffic management to C:S, perhaps what stands out the most for C:S is how the simulator determines vehicle routing
(20:47:35) god_donut: as we know, in SC4, vehicles are inclined to choose the shortest route in terms of distance
(20:48:04) god_donut: now here is where C:S differs - routes are chosen based on network speed
(20:49:02) god_donut: in SC4, suppose you had two individual residential or commercial/office areas and a highway as well as an avenue connecting the two
(20:49:32) god_donut: and suppose that the highway took some unusual path that ultimately resulted in the total length of the highway being longer than the avenue
(20:49:56) god_donut: your sims would take the avenue simply because the distance was shorter, even if the highway would still be faster
(20:50:25) god_donut: the same scenario in C:S would mean that most residents would choose the highway over the avenue because of the higher speed limit, and more technically, decreased trip time
(20:50:52) god_donut: this means that, effectively, unlike SC4, residents are programmed to actually use the highways you have set up
(20:51:10) god_donut: however, the default simulator has some problems that can make highway traffic management a pain
(20:51:45) god_donut: one that has received many complaints but no real solution is that they will all attempt to use just one lane on the highway
(20:52:27) god_donut: another is that they do not follow proper rules for merging and exiting, meaning that you will have residents crossing 3 lanes of traffic immediately after entering the highway, or using a right lane exit ramp from the middle or left lane
(20:53:18) god_donut: what the TM:PE mod does is provides a new set of merging and exiting rules for highways
(20:53:22) god_donut: *TM: PE
(20:54:09) god_donut: we'll use some images to compare pathing in the default simulator and pathing with the TM: PE simulator
(20:54:24) god_donut: first, we have a simple entrance ramp with a merging lane:
(20:55:18) god_donut: in the new simulator, traffic will use the merging lane to enter the highway, and as the merging lane ends, move into the lane immediately to the left (or right for left entrances) and later on, change lanes if necessary (this will be covered later)
(20:56:40) god_donut: in the event that the merging lane continues or is a part of a de-acceleration lane further down the road (on american roadways this would be an exit denoted with an "EXIT ONLY" banner), traffic will simply move into the next lane before the next exit
(20:56:50) god_donut: as we see in a real life scenario (most of the time)
(20:57:04) god_donut: now here is what the default simulator will attempt to do:
(20:57:21) god_donut: the graph is confusing, yes, but so is the simulator itself :P
(20:57:41) god_donut: first we have traffic using the entrance ramp merging into whatever lane they choose straight out of the gate
(20:57:56) god_donut: and not only that but we have traffic in the right lane ahead of the entrance trying to enter the merging lane!
(20:58:18) brian54[seminar]: the automa in sc4 does the same
(20:58:24) god_donut: in real life this would be a dangerous scenario, and in C:S this leads to severe traffic congestion
(20:58:42) god_donut: brian54[seminar] the first or second example?
(20:59:02) brian54[seminar]: well the automa ins c4 has some general tendencies
(20:59:12) brian54[seminar]: but as u know its quite limited when compared to CS
(20:59:18) brian54[seminar]: and what your now describing
(21:00:10) god_donut: in any case, with TM: PE's highway merging/splitting rules enabled, there are two fundamental guidelines to follow, as demonstrated
(21:00:36) god_donut: 1: each inbound lane SHOULD have exactly one outbound lane
(21:00:49) god_donut: this means if you have a two lane ramp on a two lane highway, the result should be four lanes
(21:01:11) god_donut: 2: each outbound lane must have one inbound lane
(21:01:38) god_donut: here is a demonstration of how this works:
(21:02:16) god_donut: we have one inbound lane (the entrance ramp)
(21:02:24) god_donut: which continues into a merging lane (the outbound lane)
(21:02:43) god_donut: however, with the new simulator, traffic will only exit into the two lane ramp from the rightmost lane
(21:02:57) god_donut: this is because we only have one inbound lane
(21:03:20) god_donut: if we wanted traffic to use both lanes on the exit ramp, we would have to add a fourth lane
(21:03:41) god_donut: the following demonstrates what we would WANT this setup to do:
(21:04:11) god_donut: provide a merging lane for the inbound ramp, and allow main lane traffic to use the exit ramp without having to move into the weaving lane first
(21:04:32) god_donut: we could add a fourth lane as such:
(21:05:34) god_donut: however, as you can see, traffic from the entrance ramp would be forced to cross two lanes of traffic quickly, ad we would still have weaving patterns prevalent in not only one but two lanes of traffic
(21:06:14) god_donut: the truth is, there is no real solution to this conundrum
(21:06:39) god_donut: what we should instead is used braided ramps
(21:07:30) god_donut: braided ramps simply place an exit over an entrance or vice versa in a braid pattern
(21:08:08) god_donut: this means that there will be no conflicting traffic between traffic entering the highway and traffic attempting to exit in a short distance
(21:08:20) god_donut: this DOT graphic shows a braided ramp concept:
(21:08:24) brian54[seminar]: are u referring to different elevations ?
(21:08:35) god_donut: brian54[seminar] exactly
(21:08:41) brian54[seminar]: u r :)
(21:08:56) god_donut: on the left side, the yellow is an entrance, and the red is an exit
(21:09:07) god_donut: and vice versa on the right side - red is an entrance and yellow is an exit
(21:09:29) god_donut: what this does is eliminates dangerous weaving patterns that also contribute to traffic congestion
(21:10:13) god_donut: this DOT graphic also shows a weaving pattern:
(21:10:34) god_donut: (highway traffic would be moving toward the right)
(21:11:04) god_donut: we have a 3 lane entrance and a 3 lane exit sharing merging/exit lanes
(21:11:25) god_donut: in any given lane, drivers are both entering and exiting the lane simultaneously
(21:11:52) god_donut: braided ramps solve this problem by placing the exit ahead of the entrance, thereby removing all conflict
(21:12:17) god_donut: as I mentioned of course, the concept of weaving lanes isn't entirely accurate with the default traffic simulator
(21:12:30) god_donut: but generally the same idea
(21:13:18) god_donut: anyways, we'll look at one more merging/splitting habit before moving on to how lane choice differs between both simulators
(21:13:41) god_donut: here is how exit ramps work with the new simulator:
(21:13:56) god_donut: traffic enters the exit lane (or de-acceleration lane)
(21:14:07) god_donut: and all traffic in that lane must use the ramp
(21:14:34) god_donut: while traffic that does not wish to exit stays in their lane
(21:14:44) god_donut: default simulator:
(21:15:05) god_donut: what happens is traffic will enter the exit lane
(21:15:18) god_donut: and traffic that isn't exiting will just try and move back into the right lane and not use the ramp
(21:15:48) god_donut: and what I forgot to include on there is that traffic in the right main lane will try to use the exit ramp even though they are not in the merging lane
(21:15:56) god_donut: also contributing to traffic congestion
(21:16:39) god_donut: okay, so that covers highway merging/splitting fairly well
(21:16:47) god_donut: were there any questions or anything before continuing?
(21:16:54) brian54[seminar]: well
(21:17:12) brian54[seminar]: the traffic sim z
(21:17:19) brian54[seminar]: is based on commute time
(21:17:29) Ceafus88[SR4]: You are doing a great Job :D
(21:17:39) Ceafus88[SR4]: No questions, I am just following along :)
(21:17:44) brian54[seminar]: the orginal sc4 traffic sim was based on distance as u said
(21:17:51) god_donut: brian54[seminar] correct
(21:17:52) brian54[seminar]: so just that comment i think
(21:18:02) brian54[seminar]: nice collection of pics by the way u used
(21:18:46) brian54[seminar]: one q though
(21:18:46) ChatBot: Omni logs into the Chat.
(21:18:49) brian54[seminar]: if i may
(21:18:52) god_donut: sure
(21:18:55) brian54[seminar]: omni welcome
(21:19:02) brian54[seminar]: were in the middle of cs seminar ok
(21:19:12) brian54[seminar]: well so the automa in cs traffic ok
(21:19:29) brian54[seminar]: u feel than its very representative of actual traffic issues ?
(21:19:41) brian54[seminar]: so as i said in sc4 there is a vague relationship only
(21:19:45) Omni: I can't stay I'm on mobile sucking up data
(21:20:00) god_donut: not entirely as you saw with the splitting rules
(21:20:03) brian54[seminar]: if u see what i mean
(21:20:08) brian54[seminar]: right
(21:20:11) god_donut: but generally, it's closer yes
(21:20:20) brian54[seminar]: but i get the sense its a better correlation
(21:20:25) brian54[seminar]: is that a fair statement ?
(21:20:31) god_donut: yes
(21:20:38) brian54[seminar]: ok carry on :)
(21:20:47) ChatBot: Omni logs out of the Chat.
(21:21:14) god_donut: okay so as I mentioned at the start, with the default simulator, traffic likes to try to pile into only one lane on the highway
(21:21:50) god_donut: this is sometimes in part caused by poor planning as you sometimes see on real highways within cities
(21:22:38) god_donut: however, the default simulator has most or all incoming traffic use one lane intentionally regardless of the highway design
(21:23:01) ChatBot: Hika logs into the Chat.
(21:23:07) god_donut: what the TMPE simulator does however, is causes traffic to space out across the entire highway
(21:23:29) god_donut: and as in real life, when a vehicle approaches its exit, the vehicle will begin moving toward the right
(21:23:47) brian54[seminar]: that is awesome :)
(21:24:23) god_donut: unfortunately however, the TMPE simulator does not increase the speed of vehicles in the left lane or decrease their speed in the right lane
(21:24:33) god_donut: but that part is covered by a separate mod
(21:24:50) god_donut: advanced vehicle options includes a feature for that
(21:25:02) god_donut: however it's been a while since I've used that mod so it may have been removed
(21:25:24) god_donut: but there is a TMPE alternative which i'll briefly discuss toward the end that introduces this capability as well
(21:26:03) god_donut: that effectively covers highway traffic I think
(21:26:14) god_donut: and the bulk of what this seminar was about
(21:26:25) god_donut: but I want to cover a few other things that aren't entirely highway related
(21:26:33) brian54[seminar]: sure
(21:27:07) god_donut: first will be what TMPE calls "priority signs"
(21:27:45) god_donut: C:S is a european game so priority signs use a set of rules similar to those in the US
(21:27:53) god_donut: priority is basically another term for "right of way"
(21:28:43) god_donut: by default, at uncontrolled intersections (intersections without a traffic light), traffic does not stop or yield at all
(21:28:55) god_donut: which can result in traffic congestion or motorists being cut off by other motorists
(21:29:45) god_donut: this is where priority signs are useful for intersections that have a particularly severe problem with this or are busy but not enough to warrant a traffic light
(21:30:16) god_donut: at a typical 4 way intersection, there is a main road and a secondary road
(21:30:38) god_donut: the secondary road would have a stop sign at the intersection in both directions
(21:30:55) god_donut: the priority sign feature allows you to set these stop signs
(21:31:16) god_donut: that function just like a real stop sign does - traffic stops, and if clear proceeds, if not waits until traffic is clear
(21:31:33) god_donut: but that doesn't solve another issue on the main road: left turns
(21:32:13) god_donut: in this case, i've found that setting yield signs in both directions on the main road will cause left turning traffic to wait for traffic in the opposite direction before turning but not stop entirely
(21:32:25) god_donut: and will not cause traffic that is continuing straight to give way unnecessarily
(21:32:55) god_donut: however, it is possible to give a roadway in an intersection absolute priority
(21:33:22) god_donut: this sign is found across europe and looks like this:
(21:33:45) god_donut: the same sign is found in TMPE's priority signs feature, and will exempt all traffic with the sign from stopping or yielding
(21:34:09) god_donut: however, it is important that other traffic in the intersection has yield or stop signs set to avoid conflicts
(21:34:26) god_donut: that covers priority signs, next we'll move into timed traffic lights
(21:35:34) god_donut: european traffic lights, believe it or not, also feature yield signs and priority signs
(21:36:24) ChatBot: Hika has been logged out (Timeout).
(21:36:24) god_donut: traffic at a controlled intersection (one with a traffic light) that has a priority sign may proceed without having to yield (typical only for straight and right-turn traffic)
(21:37:42) god_donut: however, at a T-intersection, the roadway turning left onto the secondary street features a yield sign, equivilant to the flashing yellow arrow seen on many american intersections, or solid green without an arrow at older intersections
(21:37:59) god_donut: is there a way to recreate this in C:S?
(21:38:04) god_donut: unfortunately, not yet
(21:38:13) brian54[seminar]: :)
(21:38:42) god_donut: by default both sides of an intersection on either the main or secondary road will have the green light in C:S
(21:38:52) god_donut: but left turning traffic does not yield to oncoming traffic in the opposite direction
(21:38:59) god_donut: this effectively forces oncoming traffic to stop
(21:39:15) god_donut: the solution to this is TMPE's ability to set up timed traffic lights
(21:40:07) god_donut: to solve left turn issues at a controlled intersection, the first thing that must be done is to ensure that the intersection has dedicated left turn lanes
(21:40:24) god_donut: TMPE also has a feature to change lane arrows, which will be looked at next
(21:40:39) god_donut: then what you can do is one of two things:
(21:41:05) god_donut: for a specified time, set a red light for left turn lanes and green for straight and right-turn traffic in both directions
(21:41:28) god_donut: and then add an entry to stop straight and right-turn traffic, and allow left turns in both directions
(21:42:14) god_donut: it is also possible to set a green light for all lanes in one direction of the roadway and a red for the other, and cycle to the next direction
(21:43:04) god_donut: this method solves conflicting left turn traffic very well, however, on an unprotected left turn traffic will simply continue to force oncoming traffic to stop from the other direction
(21:43:32) god_donut: anyways, finally, one more concept
(21:44:25) god_donut: the mod allows you to change which direction a specific lane may take at an intersection
(21:44:53) god_donut: generally this should work the same as the highway merging/splitting rules
(21:45:05) ChatBot: Darth has been logged out (Timeout).
(21:45:29) god_donut: each lane at the opposite of the intersection should have a corresponding straight arrow
(21:45:42) god_donut: and "extra" lanes used for left or right turns
(21:46:20) god_donut: it is also possible to use a dual left/straight, however this does not work well when you stop left turn traffic while thru traffic proceeds in both directions at a timed intersection
(21:46:41) god_donut: because a vehicle wishing to turn left in the dual left will hold up traffic in the same lane that is proceeding straight
(21:47:33) god_donut: one thing to note is that emergency vehicles will completely disregard lane arrows
(21:47:46) god_donut: and will also disregard traffic lights and priority signs
(21:48:18) god_donut: while changing lane arrows, there are also three other options for controlling traffic at the intersection
(21:48:34) god_donut: the first allows vehicles that are going straight to change lanes in the intersection
(21:48:48) god_donut: the second allows u-turns, and the third allows vehicles to block an intersection
(21:49:21) god_donut: by default, traffic will not attempt to block an intersection, instead will wait until there is a clear path ahead
(21:49:31) god_donut: normally this is what you would want, but there are some exceptions
(21:50:01) god_donut: suppose you have two intersections within a few units of each other, and traffic slows down to turn left at the second intersection
(21:50:25) god_donut: this will cause traffic to back up on the other side of the first intersection as there isn't a clear path ahead due to slow-moving left turn traffic
(21:51:17) god_donut: the solution here is to either space the intersections out more, or allow vehicles to enter the blocked junction, keeping traffic moving
(21:52:03) god_donut: if you choose the latter, be sure that you don't end up causing a total gridlock in your system simply due to vehicles blocking intersections in succession
(21:52:15) god_donut: as seen in this conundrum:
(21:52:42) god_donut: TMPE has two other features: the ability to set speed limits and disable vehicle despawning
(21:52:51) god_donut: I won't explain those in detail because they're very straightforward
(21:53:13) god_donut: the former simply allows you to change the speed vehicles travel on a road segment in kilometers per hour
(21:53:47) god_donut: by default, vehicles or pedestrians will simply vanish if they don't reach their destination in a timely manner
(21:53:58) god_donut: the disable despawning feature removes this
(21:54:23) god_donut: this can make for a very difficult traffic management challenge as ALL vehicles will remain on the road from the time they depart to the time they reach their destination
(21:54:31) god_donut: anyways, that's about it

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Very insightful seminar @god_donut :D I really enjoyed learning this, as transit is probably my worst area in city building games. D: Excellent Job! :D 

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I don't think I've indicated to you that I have learned a great deal of information through this seminar. I was always sketchy on certain parts about the behavior of traffic in C:S because I never got around to reading up about it. Thank you for posting this!

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