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Comment by Reason077 | Hacker News Reader

London has quite a few intersections that work this way: most famously, Oxford Circus. But most are not marked in any special way so there's nothing obvious to let you know you're allowed to cross diagonally.

I suspect the real reason for them is to improve the flow of car traffic at the expense of pedestrians - since pedestrians now only cross once in each light cycle instead of twice!

A more worrying recent trend (also in London) is to remove the pedestrian signals all together. Rather confusing when you first ecounter it - I guess you're just supposed to cross with the vehicle signals or "when it's clear".

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Relevant difference between UK and American pedestrian lights: When you see the "Green man" in the UK, the cars will not cross your walkway. Contrast the US, where cars can and do legally cross an active pedestrian walkway (turning at a green light, turning right on a red light, etc - this tends to alarm British pedestrians abroad!).

At many junctions, this means no cars may have a green light while the pedestrians cross - so crossing diagonally is a natural extension.

(However, most large junctions have workarounds - usually turn-only/straight-only "filter" signals - which allow simultaneous but isolated pedestrian and car traffic. What's unusual about Oxford Circus is that it doesn't.)

> this tends to alarm British pedestrians abroad

Yes I've experienced that alarm when in the US! I've been going to cross at a green light but cars are still moving across the crossing. Who has right of way?

The pedestrian. You just have to master "the predestrian glare" of making slightly-judgmental eye contact with any drivers that look like they may be wanting to turn into where you want to walk. :)

I wonder how this will work with self-driving cars. Making eye contact is not an option.

The self-driving car detects a human at the edge of the intersection and hesitates briefly. If the human begins crossing, it waits for them to cross; if the human doesn't, the car proceeds cautiously through the intersection, ready to brake smoothly if the human suddenly steps out.

Yup, and furthur refinements can detect intent, hesitation, emotion, and other kinds of social signalling. (Drivers, bikers, and pedestrians will use non-verbal cues to negotiate; this happens in other contexts too)

The first court cases where someone purposefully throws themselves in front of a moving self driving car will be interesting. Obviously I hope this never happens, but it's inevitably going to happen at some point. Hopefully the sensors are gong to be good enough to be able to save those individuals with no injuries. Though I guess from the car's perspective, this is identical to an animal or child darting into traffic, so this will have to be accounted for in some capacity anyway.

Is there training data for suicidal pedestrians? Does it even happen often enough for a vision network to pick up on those queues?

People purposefully jumping in front of (slowly) moving cars is enough of a problem in some parts of the world that basically every car has a dashcam now. Not suicidally though but trying to get compensation.

Well, the sensor system in a self-driving car conveniently fills the role of a dashcam as well. Logged sensor data will make many accident investigations much easier.

What if as the owner of the car I don't want the sensor data released? Will self driving vehicles move toward a (much of) software like model where we only are getting a temporary license and some other entity can change the rules out from underneath? I'm really excited for self driving cars, this is just one more of the many interesting legal/social questions I look forward to seeing debated.

I've watched self-driving cars trying to make a right turn get "stuck" behind a continual stream of pedestrians. Human drivers will eventually aggressively poke through, but self-driving cars are a little too timid for that.

They could move forward very very slowly

That strategy sometimes works with crowds (e.g., home game weekends in college towns). But sometimes, things turn ugly.

Glare at its forward camera.

That can work if there is also an anthromorphasization (put a human-like face that people can relate too). There was another article talkinf along these lines -- a disabled person trying a telepresence bot for the first time at a tech con saya he did not get the usual courtesy or respect. I suspect people didn't pattern match on it being human.

(I also found "glare at its forward camera" funny and ironic -- we humans have a lot to learn about relating to non-humans.)

It is an option, and I think a pretty effective one in the future. If advanced enough, self-driving cars could learn the different cues we give each other to communicate (be it with a car driver, a bike rider, a pedestrian, or any other agent).

It will be very interesting to see how this dynamic evolves over time.

For it to really be equivalent to eye contact, the car needs to somehow signal that it is aware of the pedestrian and their intent.

I can only hope they'll show old-timey clips on a screen, like Flubber's Weebo.

Self-driving cars won't need the glare, because they will be programmed to respect right of way, including but not limited to pedestrian right of way, or the manufacturers will be crushed by recall/repair/replacements costs and defective product liability lawsuits.

Individual drivers are a bigger enforcement problem.

In British terms, the green light temporarily turns your pedestrian walkway into a zebra crossing. You have legal priority, but some drivers are assholes.

Well, arseholes spelling wise, but wankers would be my chosen vernacular in this situation. Agree completely otherwise.

There is actually an official rule: "Remember, if a pedestrian makes eye contact with you, he or she is ready to cross the street. Yield to the pedestrian." [1]

[1] - https://www.dmv.ca.gov/portal/dmv/detail/pubs/hdbk/right_of_...

Another difference I appreciate is that UK traffic lights cycle red -> yellow -> green. So, given a red light I have at least 1-2 seconds that's safe, and usually more since the timing can be inferred from traffic patterns (cars won't get a green light while there is active cross traffic). I always look more at the vehicle lights instead of pedestrian lights -- I don't particularly trust drivers to pay attention to pedestrians or our signals...

More accurately the sequence is red -> red & amber -> green -> amber -> red, so you can always tell which state is next.

I'd never realized this, even after a year of living as a pedestrian in the UK, but this finally answers my question of why the pedestrian lights take so freaking LONG to turn green here. It may be intended as a pedestrian-friendly measure, but it FEELS like an intense annoyance, and the natural result is that everyone just crosses on red.

At least in London another difference is that you don't often see traffic lights across the intersection from cars, so it is harder to peek at the traffic signals and know when your crossing is about to go (or whether that approaching car is going to stop or go through the intersection.) Annoying.

As a UK resident holidaying in California, I was confused both as a pedestrian and as a driver.

As a pedestrian I learned to claim the right of way and cross when it seemed safe.

As a driver I was unable to resolve my confusion regarding turning on red light. If there were no vehicles queued behind me I would wait for a green light. I would otherwise typically wait for a sufficient amount of beeping from other vehicles to then assume that turning on a red was what I should be doing.

Were you aware that turning right on red is legal in most of the US but chose not to, or did you not know?

I usually choose not to turn on red when driving in the US when when it's busy. I consider it safer to wait for explicit priority.

That's perfectly acceptable if you ask me. I have a cranky manual transmission, I don't want to put myself in a dangerous situation just because I have to accelerate at max speed and possibly stall the engine.

At least, as far as I know there are no mandatory right turn on red laws in effect in the US

being Italian I never assume that cars WON'T cross my way

>Contrast the US, where cars can and do legally cross an active pedestrian walkway

And they get angry when the pedestrian takes the right of way. Cars will consistently enter traffic and try to encourage me to get out of their way, i.e. they've begun their left turn and will continue to move at 5mph through the intersection which has worrying oncoming traffic, while I'm crossing the street at a crosswalk.

I wonder whether the Oxford Circus crossing is actually just an attempt to reduce the number of pedestrians walking around the outside edges of the junction - it's pretty disorientating coming out of the Tube and not knowing which corner you're on, and the entrances seem to get in the way of pedestrian traffic trying to cross non-diagonally.

There are markings at Ox Circ but maybe a bit subtle http://themediablog.typepad.com/.a/6a011570c131b2970c0120a64...

To my knowledge there is one of these in Chicago on State street and (I believe) Jackson. It is near a college campus which I think is the reason for the special treatment for that intersection.

I've crossed a few times Oxford Circus before I realized that it can be done in diagonal. It's totally not obvious. Even after seeing the cross from above (on Instagram).

I'm not following re: "pedestrians only get to cross once". In traditional signaling, each crosswalk is also usable by pedestrians once per cycle; no?

A full cycle of the lights involves each direction of vehicle traffic getting a green light once.

In a "scramble", pedestrians would only get one total walk signal per cycle of the lights. In a non-"scramble", pedestrians get multiple walk signals depending on direction, just like vehicles do. For example, if a north-south road intersects an east-west road, in a non-"scramble" there will be one walk signal for pedestrians going east-west who cross the north-south road, and one walk signal for pedestrians going north-south who cross the east-west road. Thus pedestrians would get a total of two walk signals per cycle.

Sure, under a traditional cycle, pedestrians get two opportunities, but each is for only half the crosswalks.

I would rather clearly own the intersection once than risk getting hit by some moron turning left twice.

Right -- you also have to consider left-turn cycles when the cross traffic is stopped but pedestrian signals will still be indicating "Don't Walk", and right-turn-on-red where you're counting on drivers seeing you in the crosswalk.

Having one cycle exclusively for pedestrians, where there's no confusion, seems safer.

At least in the scramble I've used in Toronto, there's actually 3 walk signals: 1 for each direction (what a regular crosswalk would have) + 1 where you can go in any direction (and all cars face a red signal).

The standard cycle has 2 phases:

1. Cars & pedestrians can cross one direction

2. Cars & pedestrians can cross other direction

"Scramble" has 3:

1. Cars can cross one direction

2. Cars can cross other direction

3. Pedestrians can cross any direction

The scramble I've used has the following phases:

1. Cars and pedestrians can cross one direction

2. Cars and pedestrians can cross other direction

3. Pedestrians can cross any direction

That would be perfect. In Quebec city it is illegal to follow cars in the direction of the green light. If there is a pedestrian signal, you must call for it and wait which makes it awfully long and inconvenient. Takes about 30sec to a min before we can cross most intersection but hey "its safer" they say.

Does that mean cars can never turn at that intersection?

If an intersection is busy enough with pedestrian traffic the left and right turns are impossible without a dedicated turn phase I think the traffic engineers can handle that slight modification. The US has a plethora of lights where turns are made explicit with green/red arrows. As a pedestrian I am not supposed to cross when the turning traffic has a green arrow as the walk sign is always the red hand.

Downtown Nashville, Tennessee has these on Broadway where there is a lot of pedestrian traffic in and out of "honky tonks" and other attractions.

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