Laser-made bike lane could save lives | Hacker News Reader

Laser-made bike lane could save lives

smh.com.au

85 pointsjulian3760 comments

I'd be afraid that the laser light could damage children's eyes if they happend to get in the way and look into the light.

Experience from Copenhagen shows that the best solution is to have the bike path on the inside of the parked cars so the parked cars function as a buffer against the moving cars.

Putting it on the inside makes it possible to make it a different level (like the footpath) so the cars cannot go into the bike lane.

37% of people in Copenhagen bike to work, so they have a significant amount of experience with bike paths: http://www.youtube.com/watch?v=UDs83Ud6Zss&t=1m24s

My personal experience shows that it's best to have no bike paths at all. I typically only use my bicycle as means of transportation here (in Vienna) and the only accidents that I had so far were at locations where the bike path crosses a street. This is also confirmed by statistics.

Compared to this, on streets I almost never have any risky situations - even on busy multilane streets. Cars see you earlier, because you ride on the same street as they do. You don't appear unexpected (for car drivers) because you overtake on the left side like everyone else. The right of way is clear, as there are no exceptions as in the case of bike paths.

In cities such as Copenhagen and Amsterdam bike paths have an advantage, because you are faster (no traffic jams) and because car drivers expect bicycles at crossings due to the high amount of bicycles. In cities such as Vienna where the amount of cyclists is relatively low most car drivers don't expect to encounter them - so even if you have the right of way on a bike path they just ignore it.

I think you are fortunate to live in a place where bicycling is already a mainstream means of transportation. However, in many places in the U.S. (Massachusetts and New Jersey come to mind for me) it's not that drivers are distracted, but rather that many do not believe that bicycles are a valid means of transportation. If you are in the lane you will encounter real hostility and agression. In these cases, I think something needs to be done to reinforce to people that bicycles have just as much right to the roadway as cars. I'm not sure bike lanes are the solution, but something needs to be done to get the number of bicyclists up to a critical mass.

Up in Vermont it has really taken off in the past 10 years. And it is people doing it for recreation, not for transportation.

The problem it seems to me is the size of the roads. Most of the time you can not cleanly get around a biker without going into the oncoming lane. On a 50mph road with bikers going 20mph you constantly have to judge the speed of oncoming traffic to see if you can safely pass or get hard on the brakes to wait. This happens a lot and is annoying.

It's annoying for the driver. It's worse for the bicyclist who has to worry about whether the driver have actually seen him as he comes barreling up from behind.

But yeah, it's true that whoever designed shoulder-less roads was completely clueless to non-automobile transportation like biking, walking, or really even scooters that can't keep up with traffic.

(Incidentally, the "coming up from behind" situation reminds me of one of my biggest annoyances as a motorcycle rider: people who come barreling up behind you when you are stopped at a light and then go hard on the brakes. They are apparently clueless to the fact that many motorbikes are rear-ended at stoplights because drivers fail to note the biker. The net effect is that you need to keep staring at your rear view mirrors ready to take off to avoid getting rear ended in case they actually haven't seen you. Really, the light is red. It won't hurt you to slow down gradually. So please everyone, don't do this.)

Here in Cambridge, UK we have a similar issue and an unusually high concentration of cyclists.

There is a significant effort to install so-called "continental-style" cycle lanes along some major routes. These really are lanes of a decent width in their own right, typically a couple of metres, modelled after the kinds of place you mentioned.

However, the opinion of local cyclists is fairly consistently that if you can't have proper facilities like that, you're better off with nothing at all than with a bit of paint on a normal width road that marks a "lane" barely wide enough to contain handlebars even if you're cycling in the gutter. It is now very clear that such lanes just encourage cars to pass far too close, and drivers to complain when cyclists do crazy things like riding in the main traffic lane because the gutter is full of water/broken glass/etc.

There is plenty of evidence now that having no lane at all actually results in drivers being more patient and giving more space when passing cyclists than having a lane too narrow to be sensible but marking it out clearly.

That works well in dense inner cities, not so sure about less densely populated areas. I think bike lanes work ok when the blocks are long and straight but there's always a problem at intersections.

Also, although shrinking, cars are bigger in the US and drivers seem to be more distracted.

Most close calls I've had were either with seniors, cell phone talkers, distracted moms or young kids, probably roughly in that order.

There aren't too many bike paths in Toronto, or Ontario as a whole. However the law dictates that cyclists have the right to use a full lane if they want to, which is quite great. If you don't feel to comfortable to have cars passing by you so close, then you can take up the whole lane, and they will be forced to overtake you as if you are a car.

Lasers aren't really that dangerous, unless they're especially bright. They have a classification written on the side which should give you some indication of whether they're weak or strong.

The really weak laser pointers won't do any worse than make you see spots for a little while, as I can tell you from personal experience.

That said, there are lasers that you have to be very careful of. The laser-pointer level, though, is generally quite safe.

Something capable of putting enough light to make a "this is a cycle lane" image that's visible in daylight is going to have to be much brighter than a laser pointer.

The illumination level on an overcast day is about 1000 lux, so to be visible in daylight the device will have to light up the bright bits of its image at least about that brightly.

The image in the picture looks to me like the illuminated area is at least about 0.1m^2, probably rather more. So that's a total output of at least about 100 lumens.

Light at the peak of the photopic curve (i.e., wavelength optimized to look as bright as possible per unit power) is 683 lumens per watt.

So the output from this thing is going to have to be at least about 150mW. That would be well into class 3B, meaning that you need a key switch and safety interlock on the device and protective goggles if you're anywhere where it could shine into your eye.

(Doing laser safety calculations properly is complicated. Don't take the above too seriously.)

When you assumed the illuminated area to be 0.1m^2, you assumed the light source to not be a laser, spread evenly over a 30×30cm square (to get 1000 lux). Realistically, a several-watt fluorescent bulb would throw 100 lumens. And would of course not be harmful to look at.

The point of a laser is that the light is /not/ scattered over a square, its a very tight circle. If it was instead over a 3mm diameter circle, that 100 lumens would be over 20 million lux. You would, of course, not want to stare into that!

Its unclear from the picture exactly how long the "line" being drawn is (3mm diameter by even 7m long is only 0.02m^2), but a hypothetical kid staring into the beam would only get hit by part of the figure; the laser beam is moving to project the entire figure. Only the part that actually goes into the kid's eye matters, and the impact is lessened by the fact that its moving and also by the blink response.

BTW: Wikipedia tells me direct sunlight is up to 130,000 lux, so that's probably around the illuminance you need, not 1,000 lux, btw.

I didn't assume that anything is spread evenly over a 30x30cm square, nor did I assume that the light source isn't a laser. I assumed that the optics were arranged to get the light from the laser distributed in the appropriate way. (There are lots of ways to do this. You could do it with a single DOE, which would probably be simplest if you didn't mind poor image quality; or with a few lenses to give you a nicely diverging beam, and then something to absorb light where you don't want it -- but that would waste a lot of power.) It doesn't stop being laser light, and it doesn't stop being subject to laser safety regulations, just because it isn't coming out as a nice collimated beam.

The point of a laser is not only that the beam is very small. It's also that it's possible for the light to be focused on a very small region of the retina, even if the beam is diverging when it enters the eye.

The illuminance needed for the figure to be clearly visible is of course an average over time (roughly, the integrating time of the eye). If you use a scanning system (which seems a bit of a funny choice for something projecting from a moving object), then indeed the beam may only be in your eye for a small fraction of the time -- but it will also be much brighter (while it is in your eye) than I assumed. The way in which laser safety changes when you consider a pulsed system rather than a continuous one (which is what you effectively get in this scenario) is complicated, but generally for a given average power it's worse to have it delivered in pulses. In any case, though, the critical scenario for a laser safety assessment is when someone manages to get close enough to the laser to get rather a lot of the beam into their eye. (You can have safety mechanisms that aim to make that impossible, of course.)

For laser classes higher than class 1, the blink response is already taken into account in the permitted exposure levels. (Class 1 safety, which this device would be miles away from having any chance of achieving, is extremely strict and basically amounts to "if you are really determined to damage your eyes using this device, the best way would be to hit yourself in the face with it". To be class-1 safe, you need to be safe even without the blink response. But that's not the issue here.)

I chose the figure of 1000 lux precisely because I wanted a low estimate, to make the point that even being very generous to this thing it would be difficult to do it without a laser powerful enough to raise safety issues. Obviously if you want the image to be visible even in really bright direct sunlight then the numbers need to be considerably higher.

I may be missing something, but when you take 1000 lux and 0.1m², and come up with 100 lumen, the obvious way to put those numbers together is 1000lux × 0.1m² = 100 lumen. That's where I got evenly spread over a 30cm square (30 being the square root of 100, to one significant digit).

I'm not an expert in the field by any stretch of the imagination, but something seems very wrong with these calculations in that throwing a several-thousand lux image of that size would be easily done with a $500 business projector.

Yes, I assumed that the light is spread over that area. I didn't assume it's spread evenly over a square of that area. Maybe the shape of the 0.1m² region wasn't important to whatever you had in mind, but then I'm really unsure what your point was since I'd already said I was assuming an area of 0.1m².

You can get very bright $500 business projectors. They aren't emitting laser light. If they were, they would have serious problems getting non-scary laser safety classifications. Part of that is because the rules governing laser safety classification are kinda paranoid. Part of it is because coherent light really is specially dangerous. (A 100W light bulb has a luminous efficiency of about 2.5%. A 2.5W laser is really, really, really dangerous.)

Anyway, you could do your eyes some serious damage with that $500 business projector. It just happens that there aren't such stringent regulations governing incoherent light sources, because the worst case isn't quite so scary as it is with lasers.

It's very hard to get blinded by a laser, but it's quite easy to get dazzled for a few seconds if one goes in your eye. Being dazzled for a few seconds usually isn't that dangerous unless you're, say, driving a car.

No sir, I don't like the idea that the inconsiderate laws-don't-apply-to-me cyclists I carefully avoid running over every day will suddenly be equipped with lasers which can shine into my eyes by accident.

But to get dazzled the viewer would have to be between the from of the bike and the ground in front of it. I don't imagine many car drivers would be there, but it a concern with children passing in front of the bike when it isn't in motion, say.

Being between the front of the bike and the ground isn't hard to imagine if the cyclist is cresting a hill.

Assuming the device is 2ft from the ground, and projecting an image 10ft out, that'd be mounted at an angle of 79° (with 90° meaning parallel to the ground). If you're coming up a symmetric 5° hill, and the beam goes over the crest, it'll go 115 feet before hitting ground. 6° hill, and it'll not hit ground until the descent ends.

(I have no idea where the device is mounted on the bike, or how far in front you'd have to project. Easily could be further up than 2ft, which would help, or further out than 10ft, which would hurt).

Or if the bike falls over.

It's a valid concern, but is it any different to dealing with a car with poorly adjusted headlights?

Very, very, very, very, very different. The lasers we are talking about are beams, which means they are not subject to significant intensity falloff over distance. Thus, the energy they put out at the source can be efficiently transmitted over great distances directly to your eyeball. This causes further problems when the laser can deliver enough energy to damage your eye, or even permanently destroy it, in less than the ~150 milliseconds it takes you to reflexively blink it. Run this thing over a bunch of broken glass and you will have legitimate problems with localized areas of dangerously high light intensity.

Also, lasers are not toys. Do not let children play with them. Do not let anyone "play" with the green ones or any stronger lasers. You are taking insane risks when you do; yes, you can probably keep it out of your eyes but it only takes a moment's inattention and you can be talking serious lifelong consequences. It's a poor tradeoff for entertainment purposes.

Not only is this design far, far too dangerous to let out into the public in a big way, even the testing was far more dangerous and hostile to the people in the area than the engineer realized.

I've only been hit in the eye with a laser a couple of times, but I'd say yes.

And I've zapped myself several times deliberately, even holding the weak little class IIIa laser pointer right up to my eye to show people that the "dangers" are too often overstated. Granted, that's only for low-wattage laser pointers. There are high power lasers where the "do not look into laser with remaining eye" warning is absolutely correct, after all, as well as a lot of different things in between. Lasers aren't inherently dangerous after all simply because they're lasers, it's a matter of how much energy they're zapping your eyes with and for how long.

So I'd have to say, no. If reasonably engineered, this would be less likely to be harmful than someone's headlights shining in your eyes. They're so focused that they wouldn't hit you in the eye for very long given that you're a moving target likely to be several meters away from the bike.

In the UK there are very few cycle lanes, generally you're sharing the road with other traffic. The city roads are small here so there isn't space for parking let alone dedicated cycle paths. I can think of numerous "squeezes" that I've been in where this device would have been great.

I don't really see how a dim green picture of a bike will help. If a driver can't see the cyclist, would he see the flat picture on the tarmac?

Hopefully, car drivers would be looking at where they are going so they might notice something being projected by a cyclist into that space.

... something projected AND moving into his way.

This projects onto the road ahead of the bike, hopefully making your presence known even if you weren't visible (blind spot, for example).

If it only shows up on the ground, near the side of the front of the car, this won't work. I'll never see it.

If this is more like a visible beam, that is also very visible before it hits the tarmac (which I doubt), then it's essentially a torch. We have those.

It nearly never happens that cars get on the bike lane (except when they park there) -- this is to protect bicyclist in the event that a driver does a right turn.

"Eighty per cent of cycle accidents occur when bicycles travel straight ahead and a vehicle manoeuvres into them. The most common contributory factor is 'failed to look properly' on the part of a vehicle driver. The evidence shows the bike simply is not seen on city streets," she said.

This can't be true. The statistics in the US say that this is 7% of accidents:

http://www.johnforester.com/LAW/Bikeway%20Controversy.htm

The reality is that riding on the sidewalk and turning from the wrong lanes are the big cause of bicycle accidents. Being hit from behind is exceedingly rare. Being doored is probably the main worry that a cyclist riding correctly should have.

(Using the correct lane should be the secondary concern. Don't go straight through an intersection from the right side of the right turn lane. You're going to get hit by cars turning right.)

A while ago I saw an image of a guy who had built a similar device which put a laser 'bike lane' behind the bike, kind of a joke giving you a bike lane wherever you go.

Putting it in front of the bike would seem like such a minor change, but puts it from being a gimmick to a lifesaver.

I think it wasn't real (just a mockup):

http://www.wired.com/autopia/2009/02/lightlanes-lase/

Even this device is a lifesafer, as it builds a very patterny visual metric of the space occupied by the biker. And the human brain loves patterns. Therefore a driver will have a very easy task at lining up his car with the biker and safely overtaking him.

Combining both designs and tweaking the projected images and colors could be an incredible step forward for bike safety.

The mockup had the lane extending behind and in front of the cyclist. They were building prototypes last I heard, but nothing ever came of it. I want to make one too.

This could really save lives. I bike to work everyday and cars usually don't recognize bikes as something that belongs on the road.

One of the biggest changes I've noticed since moving from NYC to California (Berkeley, and then Santa Cruz) is recognition on the road.

That's because bikers (even well behaved ones) are annoying to deal with. Even if you are following all the rules, I still can have a hard time getting around you if the street is busy. Pretty frustrating dealing with a bicyclist climbing a hill at 5mph on a busy main road when you don't have quite enough room to safely get around them.

That's not even counting the bicyclists who blow through stop lights, stop signs, don't stop for pedestrians at crosswalks, ride on busy sidewalks.

In my honest opinion, I don't think bicycles belong on roads (at least in city areas).

I'm a very data driven person. Here's an experiment I did that ended up changing some of my driving habits.

The important data to me is my total driving time from A to B. So, I measured my total driving time to and from work. I also noted the number of bicycles I had to pass on that journey. If the cyclists were slowing down my total commute time, then there should be a trend in average driving times with 0, 1, or 2 cyclists encountered. No such correlation exists in my data. On average, red-lights and other traffic have more impact on my commute time than do delays caused by cyclists.

My conclusion: my emotional response to a cyclist was not proportional to any measurable delay. Now I wait calmly for a safe place to pass, secure in the knowledge that, on average, it doesn't delay me at all.

(obviously your commute time could be affected differently than mine, but I encourage you to look at the actual delay, and see if your frustration is warranted)

The slowdown effect is lower on the list of concerns than the knowledge that a slight mistake on the part of either parties probably results in the death or serious injury of the cyclist. I just find driving around cyclists stressful.

The closest comparison I can imagine would be if there were no sidewalks in cities and you had to deal with pedestrians on the side of every road as you were driving.

Wow this is a great idea, I often see drivers trying to make left turns in my city and not see bikers who are coming next to them in the bike lane (they have a 2 way protected bike lane.) It can be tricky sometimes for the driver but this would give them more information.

There is a special place in hell awaiting the drivers who overtake cyclists then do a sharp left turn (I'm in the UK so this means they are cutting in front of you).

I used to do a fairly reasonable commute every day through the center of Edinburgh and the problem of car drivers overtaking and turning left was probably the single biggest danger I had.

Here in Tokyo it's Taxi drivers, with automatic doors.

How's that, can you explain?

They can open the rear doors remotely, and often do while handling money or writing something.

This maybe works well when there's only one bicyclist, but what if there's a whole group, with half of them using these laser projectors? There would be a huge green mess on the road, not very practical.

Besides that, governments will never allow random citizens to make their own street marks. It interferes with traffic regulations and laws.

I feel like you've misunderstood the aim here. It's not /really/ to create a new cycle lane, it's to provide a visual indicator of the presence of a bike in a place where a motorist who has a cyclist in their blind spot will see...

Lots of them will provide a very noticeable indicator, and that's good.

A very noticeable green mess

Exactly. It's not intended to be a "street mark" but an attention-getter. Bright green mess on the road? Where's that coming from? Yikes! A flock of bikes! (I did not intend to rhyme ... :-/ )

Sure, sure, it's a great idea to shine a laser on the ground for safety.

Until all the cats in the neighbourhood start chasing you....

This is a great idea. If I biked more regularly I'd want one of these.

In downtown where cars are bumper to bumper, the location of the green laser would require a sharp downward angle to see it; which begs the question, does this just add another spot that drivers need to check now?

I can see it working in more open roads where this would be easy to see up ahead, but when space gets narrow, the visibility angle becomes tough.

Valiant effort though.

Looks great, until you ride up a hill and project the pattern into the sky!

This device will be particularly cool in foggy conditions or in smoke.

What grade did you get in geometry?

I wonder how much of bicycle accidents are caused by frustration of drivers rather than not being able to notice the rider. This product might be trying to solve a problem that doesn't exist.

How does frustration of drivers cause accidents? They run over a cyclist to let off steam?

I've had it more than once that a driver tries to deliberately drive me of the road. In one case where I stopped and wanted to wait until the driver is gone, he stopped, got out of the car, and wanted to start a fight. The reason in that case was that he was angry, as I overtook the waiting cars at a red light.

That's one of the reasons why I typically have a heavy u-lock and a pepper spray with me when cycling.

There are a huge number of cycle helmet videos over Youtube, in most of them you can see that the driver is out to get the cyclist, probably because of clogging up a fast flowing road.

It's not right but it's happening all the time.

They're frustrated by a (relatively to them) slow cyclist that they can't overtake right now, so as soon as an opportunity comes in, they take their chance in a dangerous way.

Just yesterday I was behind a slow-moving cyclist on a winding road with no passing spots. Three cars behind me flew out into one of the many blind corners to pass with no way to be sure it was safe.

That sums up nicely why I hate cars and driving. I just don't trust normal people with heavy killing machines under their asses.

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