If you’ve ever driven on an unlit road, or a wet one, you’ve probably realized the value of good line markings. Freshly-painted white lines are easy to follow, while faded old lines can turn even an easy journey into a taxing one as your eyes work overtime to keep you on track. But what if there was an even better solution? What if the lines illuminated themselves?
Down in Australia, thevState of New South Wales is now experimenting with glow-in-the-dark lane markings. The aim is to increase visibility beyond what’s possible with regular painted lane lines, which should ideally help drivers to stay on the road. Glowing lane lines also hint at the possibility of solving an age-old problem—road markings that disappear when the rain starts coming down.
It seems like such an obvious idea, which raises the question—why aren’t glow-in-the-dark lines the norm? To understand why, we need to examine how lane lines work, why they sometimes disappear, and explore the history of glow-in-the dark road markings.
New South Wales is testing glowing road markings.
This is what it looks like during the transition from day into night, at the initial test site in Cudal.
via Transport NSW pic.twitter.com/mzd4OEv36G
— Lewin S. Day (@rainbowdefault) December 19, 2024
Like Tears In Rain
Many young drivers have all faced a common peril. That first drive in the rain on a busy highway, where all of a sudden the lane lines just seem to disappear into the tarmac—and it’s even worse at night. It’s a common problem that has proved remarkably difficult to solve.
Normally, lane markings are easily visible, even when driving at night. This is because they have tiny retroreflective glass beads embedded in the paint. These are designed to bounce light from your headlights back towards you, so that you can easily see the lines in the dark.
However, when the markings get wet, the water ruins everything. It bends the path of the light so it’s no longer reflected back towards you. This makes the markings very difficult to see.
The seemingly obvious solution would be to have lane lines that light themselves up. Rather than having to reflect light, they could just emit their own light in all directions, making them obvious in a wider range of conditions. Simple, right? Plus, you’d get the benefit of increased night-time visibility in dark areas, too.
As it turns out, glowing lane lines aren’t science-fiction. Down in Australia, at least, they’re currently a reality. Whether or not they’ll become widespread, however, is another matter entirely.
The Glow Up
In December, the government of New South Wales announced a new line markings trial on a Bulli Pass, a a mountain road just south of Sydney. The “Glow Roads” project would test the use of photoluminescent lane lines, which absorb sunlight during the day and emit light at night. Put simply—we’re talking about road markings that glow in the dark. On rural roads where street lights simply aren’t practical, the idea is that the glowing lines will be more visible and obvious to drivers.
The first area to receive this treatment was a tricky hairpin turn. The spot had seen 125 near-miss incidents recorded in the darkest hours from 9 pm to 4 am. The glowing markings in this area are specifically intended to make the sharp bend more obvious at night, giving motorists the best chance to make the corner without incident. ““Being able to see the shape of the road ahead is critical to safe driving and that’s what Glow Roads do,” said John Graham, NSW Minister for Roads.
“Data shows around a third of fatal crashes in NSW happen at night,” noted Graham. “If this trial is deemed a success, we will look at its application on other locations with a history of crashes or near-misses where better visibility is needed.”
“The Glow Roads is the brainchild of one of our transformation teams here at Transport who–trying
to find a solution to boost safety at remote or isolated sites–pitched the idea at an in-house
innovation challenge,” said Transport for NSW Secretary Josh Murray. “Before rolling ‘Glow Roads’ out on public roads, we tested the new line markings and glow paint under a range of conditions at our Future Mobility testing site to make sure it was ready for the next phase of the trial.”
It’s hoped the glowing lines will be particularly beneficial during extreme low-visibility conditions.
“Locals know this road–and others like it across the state–can have visibility plummet in seconds
when fog or a storm rolls in,” said Jenny Aitchison, NSW Minister for Regional Transport and Roads. “I’m excited to see how this innovation performs in those conditions.”
It’s clear that there’s a lot of enthusiasm for this project within New South Wales. Drivers and bureaucrats alike will be watching carefully to see if the project actually delivers on its promise to improve visibility and safety.
Mixed Success
The idea of glowing road markings is so intuitive, that you might wonder why it hasn’t been trialed before. In fact, multiple jurisdictions have tried this concept over the years. And yet, no widespread adoption of glowing lane lines has happened to date.
Indeed, the Australian state of Victoria ran just such a trial in 2022. The media all jumped to report on the story, with much excitement about the new glow-in-the-dark lines. Precious few ever followed up on what came of the study. I reached out to the Department of Transport and Planning to find out what happened, and was disappointed to learn the results. In the department’s own words, it was not considered a useful technology for improving safety:
The Department of Transport and Planning trialed the use of photoluminescent linemarking on five rural roads as part of a road safety project.
An independent evaluation on the road safety benefits of this technology was conducted once the trial concluded. It is noted that this did not include very low speed environments such as tight curves on high speed roads.
The evaluation report determined there were insufficient road safety benefits to justify the rolling out photoluminescent linemarking on more roads. There may however be greater benefits for use in situations where no headlights or street lighting present like shared user paths.
The state of Victoria tested thermoplastic luminescent coatings that were laid down on top of existing lane lines. Goopy!
Ultimately, the trial ended without further deployment, as an independent investigation found the technology brought “insufficient road safety benefits.”
Other countries have come to similar conclusions. As covered by the BBC, the Netherlands was one of the first to the party. Authorities tested a glow-in-the-dark treatment in 2014 on a stretch of the N329 highway, with great hopes for its performance. The intention was that the special glowing lines would charge up from sunlight during the day, and glow for eight hours into the night—far longer than traditional glow-in-the-dark coatings. It was hoped they could even be a viable substitute for streetlights in some cases as an energy-saving measure.
Just a few weeks later, though, it was found the paint performed poorly under heavy rainfall. The moisture degraded the glowing line markings, slashing the light output. Under the conditions where the lines might prove most useful, they instead failed completely. Drivers were also intentionally switching off their headlights to try and see the glow-in-the-dark effect, suggesting the glow wasn’t much use when a driver’s lights were on. There were hopes for a 2.0 version of the glowing lane lines, but it never came to pass.
Shell released a fancy video on the glowing lane lines in the Netherlands in 2017—three years after it was found the technology wasn’t up to scratch.
Malaysia also experimented in this regard in 2023. Over 1,600 feet of line markings were laid on the intersection of the B19 and B16 highways. The paint used was intended to glow for over 10 hours, and to aid visibility in rainy weather.
Sadly, it was found the glow in the dark paint was 19 times more expensive than regular line-marking paint, and didn’t perform well, either. Reports from the ground suggested the glowing paint was losing effectiveness or wearing away after just a few weeks. Ultimately, the government decided not to deploy the glowing line markings on any further roadways.
It’s worth noting that regular white lane lines are really good when they’re well maintained. The vast majority use glass beads to give them a retroreflective quality, so they bounce light from a car’s headlights right back at the driver. This technique works very well—cars provide ample light and the line markings are usually readily spotted. The main problem is when these markings fade or deteriorate, with the glass beads getting damaged over time. However, this is a maintenance problem that glowing lane lines don’t actually solve.
As for glowing road lines, they are hamstrung by the fact that they only provide a very dim light. Most cars, particularly those with modern headlights, spray out a ton of light onto the road ahead. The additional light from a glow-in-the-dark coating doesn’t necessarily add a whole lot. Think about it this way—if you ever had glow in the dark stickers, do you remember how you had to be in a nearly pitch-dark room for them to work?
Rain, Rain, Glow Away
In the years following the Netherlands project, there was still a glimmer of promise for the prospect of glowing lane lines. As we explored above, it’s well-known that rain limits the reflectivity of traditional reflective line markings. The hope was that glowing markings would prove more visible under these conditions, by emitting light rather than merely reflecting it. Enter the Utah Department of Transport (UDOT).
Starting in 2020, UDOT ran some limited studies on luminescent road paints in 2020. Working in partnership with the University of Utah, the agency investigated solutions to the problems in the earlier Netherlands trial.
Researchers were aware that the Dutch effort had found that rainwater leached out the rare-earth elements that were key to making the paint glow. The research effort culminated in a custom polymer coating for the glowing ceramic phosphors, intended to protect against moisture degradation. However, it wasn’t enough to see widespread deployment of the technology. Despite the enthusiasm, Utah still isn’t paved with a network of glowing neon roads, Instead, UDOT has focused on laying down contrasting black and white lines to improve visibility in rain, rather than relying on glowing coatings. It’s also figured out how to make retroreflective coatings last longer. By laying line markings in grooves cut into the pavement, the reflective glass beads are recessed enough that they’re safe from damage from snowplow blades in the winter.
Not Good Enough
There have been a great number of studies and real-world tests of glowing lane markings, all around the world. Authorities have hoped they’ll better show drivers the contours of the road in dark areas, or that they’ll make lines pop more in foggy, wet, and rainy conditions. Yet, in the face of all these efforts, no transport department has ever pursued widespread deployment of glowing road markings.
It appears to be a problem of both performance and durability. Glowing lane lines don’t do very much, and they don’t last very long, either. No major studies have come out to say that glowing lane lines have massively improved visibility or reduced crashes. While they’re cool to look at, transport authorities focus on science, not aesthetics. If the numbers aren’t there to support the deployment, it doesn’t happen. Furthermore, most trials have had problems with the rapid degradation of glowing line-marking paints. The last thing transport departments need is a new marking material that needs to be reapplied more often at greater cost.
The New South Wales effort could prove viable, as the state is trialing something very specific. In particular, the hope is that using glowing markings on a tight hairpin will catch driver’s attention and keep them from running off the road. While it seems that glowing markings aren’t a real upgrade for regular roads or highways, they might have a useful application on dark roads in tight, slow-speed corners. In these spots, running off the road can be all too common, with dangerous consequences. However, glowing markings would still have to outperform traditional solutions like signage and road reflectors to be worth implementing.
For glowing road lines to be really useful, they’d have to be far brighter, and far more durable. For now, though, unless we discover some wild new phosphorescent materials, we’re unlikely to see much progress here. Perhaps one day we’ll see LEDs or other powered light-emitting technologies that illuminate the roads. As far as glow-in-the-dark lines are concerned, however, the technology simply doesn’t seem up to the job.
Ultimately, unless you’re in New South Wales, you shouldn’t expect to see glowing lane lines any time soon. Thus far, the only thing they’ve really been good for is giving transport departments some good photo opportunities. They look great, but after a decade of trials, they’re yet to prove more than a novelty. It’s a shame that these whimsical glowing roads aren’t more valuable, but for now, that’s just reality. Meanwhile, UDOT’s efforts to improve visibility in wet conditions are relatively simple and accessible, and are perhaps more likely to spread if proven to be significantly effective.
Lane marking is an esoteric art that you probably never think about. Nevertheless, a great deal of thought and engineering goes into making the lines on the road as safe and as visible as possible. The flashy glowy techniques might not be worth a whole lot, as borne out in many studies, but that doesn’t mean there aren’t improvements out there to be had.
Image credits: Transport NSW, Transport Victoria, Minister of Works Alexander Nanta Linggi via Facebook, UDOT, Shell via YouTube screenshot
It is a French company OmiKron which seems to be behind the revived interest, with its multi patented “photolumincent” product supposedly based on plants.
They say most sales so far have been for cycle lanes, which might point to the problems with roads.
Good old British cats-eyes are the best, even if bikers hate them.
Do they have something against chevron signs for sharp turns and cat’s eye reflectors for lane markings? Those things are effective in all weather conditions except snow for the cat’s eye reflectors (chevron signs still work obviously). They are proven, durable, dead simple, and not overly expensive. No road surface marking is going to work in snow anyway. To me this is a long since solved problem, especially for the sharp bend situation.
My first thought as well, and what I’ve seen at plenty of sharp turns. Additionally, you can have lights with solar panels to charge during the day and add another layer of visibility. That wouldn’t be the main method of course, since solar exposure can vary enough to not charge the batteries at all, but it doesn’t hurt and isn’t wildly more expensive.
Back in 2014, CDOT started experimenting with in-pavement LED lighting on sections of I-70 west of Denver. It expanded the experiment to Highway 93 just north of Golden in 2017. I’ve found these LED lights to work well during snowstorms.
“Data shows around a third of fatal crashes in NSW happen at night,”
You want to cut road deaths by two thirds?
Permanent darkness.
You’re welcome.
They look cool though
We need a return of the cat eye markers embedded in the road surface.
Equip each of these and all other road markers of every kind with a passive RFID device and then you also have a solution to keep self driving cars on the road in any weather condition, regardless of visibility. The car would triangulate using data from several RFIDs at a time, and confirm with GPS readings and inertial navigation calculations from the last known and confirmed point.
As they drive by, self-driving cars would constantly confirm and update the database of RFID traffic devices, so that if one gets knocked loose, it’s automatically marked as “out of place” and scheduled for replacement.
Updating maps for road construction in progress would be simple and pretty much automatic with these devices in all the cones, barrels and berms. And it would be just as simple when the construction ended.
RFID is already cheap to make. Economy of scale would make the RFID devices trivial in cost.
My sti was the worst, imagine roads having 0 lines in the rain w lights on. Turned off headlights for a section and lines came back. Didn’t like it but liked finding a ditch at 40 mph less
Hid w no fogs was the reason if you missed it. Normal halogen headlights were fine, as were normal fogs as those might make the road 2d mounted so low, but w markings in the rain. No streetlights either.
in Colorado (Hwy 93) they were testing LED lights for the lane markers in critical areas. They are pucks inserted in the pavement with a small LED light.
https://www.codot.gov/news/2017-news/december/drivers-to-benefit-from-in-pavement-led-lights-on-co-93-from-64th-avenue-to-co-72-in-golden
CDOT uses LED lighting on sections of I-70 west of Denver as well.
Some of the roads in NC have this issue, but for people with newer cars that have all that lane tracking/centering tech and cameras that stuff really does help(if you know how to turn it on), had a rental hyundai, say what you will about the mechanical quality but during a storm that lil car really helped because it saw the road better than me and my glasses.
So what’s wrong with solar powered streetlights?
When it’s nighttime and rainy, give me darkness and my headlights 100% of times over fricking streetlights. Their light reflects off the road surface causing glare, also reflects off your windshield, dashboard, etc.
There are some pretty well designed highway lamp posts that mostly avoid glare and essentially turn night into day, but for rural roads, no thanks, my headlights work much, much better.
If that were the case there would be no need for this glowing paint. Clearly head lights alone are not a solution for everyone.
Agreed. I suppose I have a personal vendetta against poor quality street lighting. To me the solution is clear: add simple “guardrails” (no need for the beefy metal ones, something like a fence would do) to dangerous roads and put retroreflectors on them. Water would not accumulate on something that’s vertically oriented. For the center line it gets a bit more complicated, but most accidents at night in rainy conditions are people going off the road, not frontal collisions
That works too and is probably the cheapest solution yet. Which begs the question why it hasn’t been done. NIMBYs? That would also explain the lack of interest in street lights.
Someone would hit it. Someone hit my apartment building one Christmas as a 3 story was hard to miss, drove through a fence too. Thankfully I got a loud bang and not a literal truck inside. top floor advantage
There are such reflectors designed to be run over and pop right back up like nothing happened.
https://www.uline.com/Product/Detail/H-4466Y/Traffic-Safety/Flexible-Delineator-Round-Post-with-Base-48-Yellow?pricode=WB3106&utm_source=Bing&utm_medium=pla&utm_term=H-4466Y&utm_campaign=Safety%2BSupplies&utm_source=Bing&utm_medium=pla&utm_term=H-4466Y&utm_campaign=Safety%2BSupplies&msclkid=3ceac8c8252b120ca4c7afac6aaf78fd
My city uses them to delineate car lanes from bike lanes but to allow access for maintainence vehicles and street parkers.
Nothing is wrong with that approach. Some locations in the mountains may restrict recharge time. It’s just not as much fun to think about. Also, you could embed solar charged LED’s in the road.
That thought crossed my mind too but I thought solar panels would not be rugged enough to handle being run over thousands of times a day and running wires from panels on the median would be complicated and expensive.
I do think however such lights will happen eventually. Those lights will I think also be used by AVs but reading coemitted lower energy invisible light like microwaves or radio waves that also broadcast precise GPS signals.
They’re perfect for the tiny minority of roadways that have the population density to warrant them. I think for most of the US (and Oz) we’re talking about cost-effectiveness over thousands of miles of semi-rural roads.
I think autonomous solar powered, battery backed street lights are a LOT more likely to make those maths work than wired lights, especially if those maths haven’t been updated since sodium vapor lamps were the norm.
I’d settle for at least proper lane/area markings in the US that don’t disappear after 6 months and are painted using proper equipment instead of drunk redneck on a lawnmower. Luxuries like reflective paint and such can stay limited to civilized countries.
What are you even yammering about? I don’t know of a jurisdiction that doesn’t use reflective paint in the US, and I’ve only ever lived in/worked in very rural areas.
You know what’s always clear and visible day or night, rain or shine?
When road crews grind off the temporary lane markings from construction.
I can always see those dark ground up sections of road surface that don’t match with the painted lines.
I find very useful when roads have that “texture” that warns you if you are leaving your lane. It gets loud and your steering wheel vibrate to alert you.
Dont forget to clean your windshield inside too, the amount of drivers that I see with foggy windshields is insane.
Cleaning the inside of a windshield is such a PITA though!
News from the year 2317: Australia’s rapidly-evolving Death Worms have developed bioluminscence in order to guide vehicle off the road and consume their injured occupants. In other news, NSW advanced to the quarter finals over New New Delhi in cricket…
“Australia’s rapidly-evolving Death Worms have developed bioluminscence in order to guide vehicle off the road and consume their injured occupants.”
Hmm
“Researchers were aware that the Dutch effort had found that rainwater leached out the rare-earth elements that were key to making the paint glow.”
Well THERE’S your problem! Regular worms + glowing rare earth elements = carnivorous glowing death worms! Everyone knows that!
Modern day Botts Dots!
I’d take just getting new markings on a regular basis. Worn-out markings are still better than ones that are barely even there anymore. And that’s here in Massachusetts where the plasticized markers are painted in grooved-out areas to avoid snowplows. We did try the cat’s eye reflectors for a while but those went away because too expensive to maintain. At this point we only get new markings when the road is resurfaced and by then it’s not the rain that’s the problem, it’s the complete lack of any stripes at all.
Definitely something I wonder about in re: self-driving cars. Growing up in dark rainy Pacific Northwest winters, I learned to identify lane markings by their surface texture in oncoming headlights. And if there’s no oncoming headlights, do the lane markings even matter?
There are times when I have completely relied on singing shoulders to keep me in line. That’s usually a sign to pull over, but that has its own risks under those conditions — getting hit by the next guy who comes along.
There’s those metal cap things that have reflectors that I’ve seen embedded in the roads that are my favorites. I know they get smashed by overweight vehicles at times but when I was young I remember being on Route 52 in Ohio which borders the river and it had these things in the road and on a very dark night with storms mixed with with patches of fog coming off the river it sure made the drive 100% safer and less stressful. It was helpful to see them have white and yellow reflectors matching the lines (and blue ones mixed in for fire hydrants). These seem ideal, worth the extra cost, and might have the added benefit of making it easier on autonomous driving systems that can scan for them.
The only other thing I can think of is a HUD with markings applied to the road but you know sooner or later those things would be wrong in places. There are HUDs with night vision as well but I don’t know how realistic it is to use such in an environment where you face headlights.
I wish there were magical polarized glasses that work at night. Meantime, I’m shopping for glasses for the first time in my life because I had to borrow my spouse’s pair the other night to drive an unfamiliar road.
I miss Botts’ Dots, but they are incompatible with snowplows. I’m a fan of recessed reflective markers but they’re hella more hassle to install than paint stripes.
Polarized lenses work just as well at night as they do by day. There’s just not much for them to do.
They should reduce surface glare from wet roads, but they cut out half the light.
That half is glare though.
Those things aren’t used in places with snow. Plows would destroy them.
that’s not true. they are all over in northern ohio. And we got 3…4 ft of snow already this season. they are recesed and plows don’t bother them for the most part.
The freeze-thaw effect helps with popping them off, too.
Cat eye reflectors and similar certainly have been used on plowed roads. They’re usually recessed, and many also have metal shoulders that are gently sloped in both primary travel directions.
Something interesting about those reflector pucks is that there is a red reflector on the other side to warn you if you’re going the wrong way. I used to drive tow trucks and the first time I had to go the wrong way to get to a crash scene, it was like “Whoa! The reflectors are all red!!”
I could swear I had seen them around whee I live, but not recently. Found out from the ol’ wiki stuff they used to be but they stopped and just use reflective paint now.