Dig It: Cities Skylines Adds Tunnels

this is the steepest slope possible, not representative of ALL tunnels

Soon, you’ll be able to add tunnels to your urban creations in Cities: Skylines [official site]. Even before the game had been released, Colossal Order had told me that tunnels were the one big feature they had been hoping to include at launch. I think the eventual outcome was the best possible scenario – the game was lovely at launch, mods instantly started to make it even lovelier, and now the tunnels are arriving in the form of a free update later this week.

I don’t know what frightens me more – the inevitable video of an engineering mastermind’s metropolis with perfect traffic flow enhanced by an entire underground transportation layer, or the inevitable video in which somebody manages to inexplicably divert every hearse into a tunnel that has no exit-point.

I’ve been working on a recreation of Salford and Manchester – two cities in one! – and while I can’t think of any particularly important tunnels to include, I might pop one under Whitworth Park just for kicks.


  1. Kefren says:

    Pop a tunnel under Picadilly Gardens (so-called). Might collapse the prison-like walls along one side as Strangeways invades the centre.

    Or if you do one in Salford then you could turn it into Dungeon Keeper, and build a central chamber in the subterannean bits. That would work as Salford has no heart. Then it would at least have a Dungeon Heart.

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      Adam Smith says:

      I fear that there’s already some kind of bunker underneath the ‘Gardens’. The big wheel is actually the only visible part of some dread subterranean machinery.

      And Salford is full of heart! I mean, sure, it’s covered in scabs in places but there’s heart underneath it all!

      • Kefren says:

        Remember the little park that used to be in front of the town hall, which always seemed to be locked up? I’d pass it on the metro and see those swings and slides, devoid of children like some mini-Mancunian version of Pripyat. Well, I got told that was actually the entrance to the nuclear bunker for the councillors.

      • Kefren says:

        The big wheel theory of yours could be true. It’s so overpriced that it must be hiding something.

      • Kefren says:

        The heart/centre comment was based on Nikolaus Pevsner who wrote about Salford in 1969) “There is not much walking to be done. Salford has no centre. Of the medieval centre nothing is left, and today‚Äôs centre is one long street, shattered by traffic.”

        (Sorry, Manchester and Salford have been an obsession of mine for years; the main character in my latest novel includes someone obsessed with Manchester music, often connected to Salford [Joy Division, New Order, Tony Wilson, The Happy Mondays, Tim Burgess, Mark E. Smith…]. Also Salford Scallies appear in one scene based on a real encounter in The Shakespeare.)

  2. cpy says:

    Those tunnels looks way too steep for my liking.

    • mrwonko says:

      It’s the steepest one possible, apparently. Like with elevated roads the slope should be adjustable.

    • Gap Gen says:

      I once followed a truck up an onramp with the first person camera and it was like riding a rollercoaster. Cities seems to be pretty lenient with the gradients you can throw down.

  3. Gap Gen says:

    I want to push a bunch of my highways underground to give more liveable space above ground, so this is good news!

  4. ulix says:

    I have come to the conclusion that the game (aka Cities: Traffic Simulator) is more or less unplayable with its current traffic simulation. I know why it happens, and I now it would be computationally expensive to solve it any other way…

    But by god, tiny little cars, just change the fucking lane if you’re in a traffic jam!

    Maybe use one of the FIVE other lanes, you know, the lanes that are completely empty, instead of standing in a jam that’s kilometers long on that one lane? Just an idea.

    It can get really annoying, and you really have to build your traffic around this annoying quirk, which is sometimes possible, sometimes isn’t. But if you do it, you sure as hell won’t have an intersection resembling anything feasible in reality. So this means it’s not a simulation anymore, more of a “work around the weird game systems” kind of thing.

    It’s even more hopeless without the “Traffic Manager” mod that let’s you change lane-designations etc.

    • Windows98 says:

      If your traffic isn’t flowing properly it may not be the game’s fault. You may just need to analyze your traffic more. Read this.

      link to steamcommunity.com

      • ulix says:

        If the cars don’t change lanes, IT IS the game’s fault. As I said: it becomes an excercise in working around the games faulty systems, instead of being a simulation where you can build streets that actually make sense.

        I know more or less how to work around the game’s shortcomings. I just don’t want to. I want to play a simulation.

        • matnym says:

          They don’t change lanes because they calculate their route before they leave. That way they only have to do one calculation per journey instead of 100. Might not seem like that big of a deal with just one car, but with 10,000+ it’s pretty much vital for performance.

          If you have a long traffic jams then it’s most likely because they are all heading the same way. Changing lanes is not going to improve traffic flow if everyone has to turn right. They’ll just end up blocking another lane which would be used by cars heading some other place.

          Before you blame the simulation I suggest you try to figure out why there’s a jam in the first place. Where are they heading? Do I have enough exits (because the AI will use multiple exits)? Did I build a massive commercial district with poor road connections (they attract a lot of traffic)? Is my industrial district right next to my residential district and do they have to share the same roads? Do I have enough public transport? Is my harbor in the wrong end of the city? Do I have any bottlenecks (e.g. busy intersections right after a highway exit)?

          I’ve yet to come across a single traffic jam that couldn’t be fixed with some simple redesigns. A bigger roundabout here, another highway exit there, a metro station over there etc.

        • Gap Gen says:

          The cars are doing what they should – if you all want to take the left exit because that’s where you want to go, then you have to queue up there or be the dick who uses the wrong lane then waits for someone to let them merge again. There’s another link that I’ve now lost that illustrates this very well. The solution is to figure out ways in which you can allow the cars to get where they want to go without all trying to use the same crossroads, get jammed behind lights, etc. Often actually removing infrastructure and making things harder to get to actually helps – it removes choke points, allows traffic to diffuse, etc. My rail network and industrial hub traffic was completely choked up, and my solution was to remove a bunch of accessible cargo stations and put only one further down the highway, meaning that now all trains had to go to one place rather than queuing everywhere and trucks were flowing evenly rather than jamming in one point.

          In the case where everyone wants to go left, consider what’s blocking them and try to remove those blockages. Turn two-way roads into one-way roads flowing away from the blockage, which has the double effect of removing intersections with lights. Make more intersections that divide traffic rather than merging them, and re-merge later in less crowded places, so that cars and trucks don’t back up. Divide industrial and heavy commercial into subsections so it doesn’t just all merge into one hellish gridlock, and keep both away from residential (offices make a nice buffer zone as they don’t generate much noise or traffic). It’s also possible to build a city that becomes one big gridlock such that you have to heavily rezone or just start again with a better traffic plan. It is true that Cities is very heavily based on transit compared to other aspects of cities, but then that’s the nature of the beast.

          Long story short: the simulation is just fine, and fixing problems with your traffic flow is a deep and non-trivial thing.

          • herpderp says:

            Actually, there are cases where the AI should use two/three lanes but instead all block one lane. A simple 50/50 split over the lanes might resolve problems and would be a cost-effective (CPU) route calculation solution.

            Case in point: highway -> 6-lane one way -> intersection to 6/4-lane -> 4-lane / smaller roads
            When turning right, the AI always chooses the rightmost lane, even if they could use the other lane to turn right (depending on where they turn next intersection, depending on how close it is)

          • Gap Gen says:

            Huh, interesting, I haven’t seen this before (although again, it is possible to avoid queues with good planning and some foresight, and yes, I did royally screw up my first city and have to restart)

      • Dread Quixadhal says:

        It’s a problem with the agent AI and the way it evaluates the path costs.

        Specifically, it appears to only use distance and not traffic delays into the edge cost, or perhaps it only uses overall road traffic costs. What the AI *should* be doing is factoring in lane traffic costs when evaluating each route, and basically treat every lane as if it were a distinct road (for THAT purpose).

        If it did that, you’d see traffic spread out and switch lanes far more often, because if there were 12 cars in the shortest lane and only 2 in the adjacent lane (which can still make progress), cars would shift. The downside is you would get merge issues closer to the intersections, where cars would start having to merge back into the backed up lanes to turn. THAT is a problem solved by redesigning the road system though.

        Basically, people are frustrated because it doesn’t ;pass the “makes sense” test. All of us driving on the road in real life know that it’s a gamble to switch to the next lane over if we have to turn, but also that if it’s a long enough line, it might be faster… unless the jerks refuse to let us back in. :)

        • Gap Gen says:

          Yeah, all you’re doing by using the wrong lane and then hoping that someone else will let you cut in line is blocking another exit for someone else and the blockage point that everyone is trying to use is still the limiting factor. It’s like buying a bigger sink rather than unblocking the drain.

    • Nosada says:

      Sounds like they should rename the game to “Belgian traffic simulator”. Huzzah for the idea that everyone deserves the right to endanger the lives of thousands, as long as it’s done with tonnes of steel at 80+mph.

  5. pitfallfritz says:

    I wish they added trams, though. That would be so lovely!
    As it is, the railway is not a very useful tool to build a public transportation system.

    Imagine the tiny little trains in the streets!

    • Gap Gen says:

      So what you can do is download the Rural Station asset mod, which gives you a smaller station. I used it to make a tram network. Granted it doesn’t run along streets (but it can cut parallel to them), but I ran it between my raised highways and then connected it via pedestrian paths to the districts along the highway. I think at some point they were considering putting in trams, though, and it was mainly a question of time before release.

      • Gap Gen says:

        Some tips: you can lay down train routes like bus and metro routes (I guess you might have already found this). Also be wary of linking the tram line to your main line, otherwise you might get intercity trains clogging up your commuter line and vice versa. Similarly, I decoupled my cargo line from my passenger line at a single point on the line running out of my city and it really improved my train circulation, which can easily get backed up as soon as you begin expanding your train services.

  6. RedViv says:

    Tunnels AND a European city tileset! FOR FREE? What in the world is this!

  7. DoktorV says:

    Once subways are in the game, Magnasanti mk2 will be doable.