Oh wait this is i-30 in Dallas.

2 way traffic on all four exits!

  • PeterPoopshit@lemmy.world
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    11 months ago

    If you make 90% the area of your city dedicated to roads leaving only 10% buildings, you can barely just get traffic under control trust me. Just like in real life.

  • Creat@discuss.tchncs.de
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    11 months ago

    The point is to avoid left turns when merging onto or leaving from the smaller road above. Keeps the traffic on it flowing.

    • Garbanzo@lemmy.world
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      11 months ago

      That only explains half of the WTF going on here. Why is there a freeway in the freeway?

      • Vent@lemm.ee
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        11 months ago

        Texas has big access roads on almost every mile of highway, and it’s glorious. If there’s one thing Texas does right, it’s highway infrastructure. Except for its obsession with tolls.

        • dejected_warp_core@lemmy.world
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          11 months ago

          Hard disagree there. Driving on the interstate south of San Antonio, there are these overpasses that are, inexplicably, on the highway itself. These are artificial hills that are steep enough at highway speeds, that your visibility is made shorter than your stopping distance. You can’t see past the top until you’re there, and they completely obscure the entire highway on the other side because it’s so straight. Obstructions, stopped vehicles, pile ups, anything could be on the other side and you wouldn’t know. Anyone on cruise control or driving a semi has their trip peppered with these possibly lethal moments at regular intervals.

          Everywhere else I’ve been in the lower 48, (slower) local roads pass over freeways, because it literally takes less dirt to make that safe.

          • Vent@lemm.ee
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            11 months ago

            I’ve never seen a highway with a hill so steep that your visibility is less than stopping distance. There’s an exception to every rule, but I’d wager that it is at most exceedingly rare. It’s definitely not regular.

            Texas has u-turns at basically every highway intersection, with exceptions like this photo. The u-turns bypass the stop sign/lights so that it’s just a yield. I’m not sure if any other states do that at the same frequency. With that design, it’s probably easier to just raise the highway since it’s a straight road rather than raise an intersection. I’m sure it also depends on which road was there first.

            The huge access roads also typically stop at intersections, unlike in this photo. In order to support that and have the smaller road use an overpass, the access roads would either need to be built much further away from the highway or curve out and in at every intersection in order to reduce the grade of the overpass’s slope. The overpass would need to be longer too since it’s crossing more lanes.

            If the smaller road goes over the highway, it’s pretty common that the highway actually goes down so that the smaller road needs to be raised less.

            I’m sure there are plenty of other positives and negatives, but I’m not a structural engineer. I’m just pointing out that it’s not an arbitrary decision and it comes with some benefits like robust access roads and u-turns.

        • Garbanzo@lemmy.world
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          11 months ago

          Are you being serious? I can’t tell because you didn’t provide any clue what the benefit is. It looks pretty god damned stupid, so good luck dispelling that impression.

    • elgordio@kbin.social
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      11 months ago

      The difference being the use of frontage roads. The entrances and exits from the main carriageway onto the frontage roads will be between this exit and the next.

      • eric@lemmy.world
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        11 months ago

        Yeah. That’s how cloverleafs look. Is this the first time you’ve ever seen one? In case it is, they’re incredibly common and the most efficient and safe way to allow cars to go all directions without any stoplights at an intersection of two highways.

        • SpaceNoodle@lemmy.world
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          11 months ago

          No, most cloverleaves use single lanes, and the resultant curves make them resemble the leaf of a clover.

          • eric@lemmy.world
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            11 months ago

            Yes, it is more common to have them be in a single direction, but the extra lane and bidirectional traffic doesn’t make it look any less like a leaf of clover.

        • Everythingispenguins@lemmy.world
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          11 months ago

          They are actually pretty dangerous because they force traffic weaving. You have high speed traffic exiting the highway crossing low speed traffic entering the highway. In times of high volume traffic they get very hard to navigate and tend to cause a big choke point. That is why you will find many cloverleaf interchanges are being replaced.