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Comment by dmurray | Hacker News Reader

The article doesn't deal with what happens when the queue gets bigger than one. It looks like a second car would queue on the main road, blocking traffic.

To eliminate this you could turn the buffer into a whole extra lane with room for say 5 cars to queue, but this would compromise on the nice feature where the partially turned car gets to completely turn and have great vision of the cycle lanes in both directions.

It's an interesting article, but from a systems design perspective I'd be much more interested in how they handle a change in requirements like "there are now five times more cars turning left here than the intersection was designed for".

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Build more bike lanes.

To an extent, it's a self-solving problem. If you have great non-car transport options and an increase in traffic makes car driving less appealing, then more people will use those non-car transport options rather than joining the queue.

And an often forgotten point: this benefits people who have to drive cars too, since there are less cars on the car road!

ebikes mean you dont need to be that fit (or sweat) either.

> Build more bike lanes.

The problem is that you may not have the room for it. The US might often have more room to retro-fit bike lanes, due to their roads be generally pretty wide. European cities, like Copenhagen have a massive issue as more and more people get things like cargo bikes and electric bikes. The bike lanes needs to be expanded to accommodate them, but there's no room. You'd have to remove cars from large parts of the city, which sounds great, except you do need to have the option to drive, either due to distances, public transport or deliveries. You can't do parking and have people walk, because there's also no room for parking.

For some cities I also don't see bike lanes as solving to much. Some cities, again often in the US have a huge area and millions of people. Distances in cities like Houston, New York, Los Angeles or Atlanta are just insane, taking up enough space to cover half of a small European nation.

At least where I live, such a type of intersection is used when a residential street branches off a large main road. You do not have a high volume of traffic going into this residential street, and "waiting for a crossing cyclist" does only take 1-2 seconds. So a buffer size of 1 is usually enough.

The backpressure is a feature and ensures people like me take a bike and train to work instead of driving

> when the queue gets bigger than one. It looks like a second car would queue on the main road, blocking traffic.

Without the buffer, a single car wanting to turn that way when there is a cycle in the lane would block traffic, unless of course the car takes priority and just expects the cyclist to deal with them cutting in front (which is my experience too often at junctions with or without cycle lanes…). In either case, with or without this design, the car slowing down to turn is going to create some back pressure if the road is busy, there is no avoiding that and this design might even actually slightly reduce that issue.

Looking at the picture I assume that most vehicles are going to be going straight on, and when someone is turning the only extra delay is when their need to turn coincides with there being cyclists or pedestrians in range of crossing, so it is likely that none of this back pressure is a problem the vast majority of the time.

If that happens rarely, then the cars just have to queue for a few seconds, no big deal.

If it becomes structural, say the neighbourhood becomes larger and substantially more cars will go there now, then the intersection will be redesigned. Money isn't infinite of course, but this sort of thing is a big part of planning new development.

Ideally more density leads to more public transport.

It leads to more traffic of all types, I guess.

I agree. The photo description for "Here you can see that a car drivers waiting for people cycling are never in the way of other people in cars" would not hold true in my area of a US. There would quickly be at least two additional cars waiting in the main lane.

Yeah, it's important to note that this design is specifically for local side streets that are only expected to get destination traffic. If it's a busier street, there would typically be a separate turning lane, i.e. a bigger buffer.

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