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, the State 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
Unless you live in Michigan, where they absolutely do not reflect any light. They might even absorb it.
And then when it rains…well…good luck.
The problem with retroreflective paint is that it depends on the difference in the index of refraction of glass and air, so putting it in water makes it not work.
Glass spheres are pretty cheap, so coming up with something that doesn’t cost more is kind of hard.
Usually I’m not one to complain, but just have to point out that this article was really repetitive. Otherwise, Lewin, and all the writers here are absolutely amazing. I’m glued to this site, which is the best site on the net!
Or how about these
https://www.tapconet.com/product/iirpm-internally-illuminated-recessed-pavement-markers
I would imagine that the cost could be vastly reduced at higher volumes.
Last time I checked in Europe – all around, pretty much – back in the 90’s, reflective (not glow on their own) markings worked just fine, rain or not. Their only issue was for motorcycles, as they became slippery in rain. What changed ?
What’s wrong with Road Reflectors like these?
https://a.co/d/aVygrSS
Easy to see and if that fails you can drive by feel!
In places with snow they have to be recessed or plows will zip them off the road.
These work extremely well. I was in the Appalachians at night during fog and heavy rain and had no issues seeing the edges of the road or the middle – they were very bright. The reflectors appeared to be buried in the road surface, so I can’t imagine they’re cheap to deploy, but they do work.
An awesome idea! Makes much to much sense for the US to ever do it.
Did you read the article? They don’t work and are very unlikely to every work. But your second sentence holds water.
In all my years of driving I have never thought the lane markings were harder to see in the rain. Am I just immune to this?
I think it just depends on where you live. In Phoenix where it’s flat everywhere, if there’s any water on the ground the led lights cause so much glare that it’s almost impossible to see the markings.
Hardly ever rains here though, that’s a different problem.
Depends where you live. In Texas I never had problems seeing lines in lanes (even without reflectors). In Utah they’re damn near invisible.
In Germany, many rural roads and Autobahnen without overhead street lamps have those Leitpfosten (delineation poles on the side of roads). They are very useful because you could actually see much further down the road how the road would curve ahead of you as the headlamps light up the retroreflective markers on the Leitpfosten. The blue retroreflective marker stripes on the side more or less solve the “deer in the headlamp” problem.
We have same problem with the markings on the streets and roads, especially the older and worn out ones. Come the rain at night, they virtually “disappear”, making it very hard to see where the roads ahead of you. So, the Leitpfosten are really helpful here.
This is the correct solution for sharp corners and high risk, high speed roads. In snow and ice conditions, roadside reflective markers remain visible, and rain beads off of the hydrophobic vertical surface of the reflector.
Many rural roads in Australia have something similar, traditionally white painted thin wooden posts (for easy breakaway) with round plastic prismatic reflectors attached near the top – more modern versions are plastic posts.
Years ago, while a friend’s car was stuck on the side of the road one night on a winding mountain road in a forest while he tried to fix the headlight relay, I may or may not have walked some distance down the road and round a bend, removing the reflectors, then climbing trees down the hillside below the road to place them in the trees so an approaching car at night would see them heading off into the distance in a straight line, rather than following the tight bend ahead……
I swear in Idaho there is no reflective beads in the paint. Totally unable to see the lines when it’s dark, let alone when raining
They are doing this all wrong, paint won’t cut it. We need radium!
It glows all on its own, we can embed it in zircon crystals so it acts exactly like the reflective glass beads that are currently used. Bonus it can slightly melt a very slight dusting of snow from its radioactive emissions.
Its a win win win, absolutely no downsides.
Just like Luminox uses for their watches!
“Data shows around a third of fatal crashes in NSW happen at night,”
So, if my maths is correct, more or less, driving at night is no more dangerous than day time? (24 hours in a day and around 8 hours of darkness in summer down here. As the nights become longer over the winter months, that statement would imply that it’s safer to drive at night in NSW?).
Depends on how much more people drive during the day than at night. If only 10% of driving happens at night because the roads are mostly empty from 10PM to 7AM or so, it’d make night driving a fair bit more dangerous.
Yes, agreed, but that distinction isn’t made in the quote (and I’m just being a bit silly). I was watching one of those fake ‘haunted places’ vids on YT a while back and they quoted ” a quarter of all paranormal activity occurs between 12am and 6am”. Uh Huh.
White stripes with a thick Vantablack border? (Or a coating that is as close to Vantablack as possible while also lasting as long as possible.)
Maybe the vantablack area could be a slightly raised matrix of columns or ridges to allow the black part to rise above some amount of water on the surface.
There are a few locations along US 101 in Silicon Valley where they paint blank in the spaces between the white lines. I noticed this around the intersection of 85 and 101 where a Tesla and driver came to a bad end.
In the opposite direction at this interchange the road surface changes from asphalt to cement. The striations on the asphalt would have you crash into the median, if you followed them. I believe this has been recently corrected.
Much like self driving cars this is a perfect situation in an unworkable situation. Show me the paint a month or two down the line. How about some snow? Just like self driving cars work in a perfect situation on a new road etc. it doesn’t work in the real world.
Just got 5” today in Minneapolis.
Lanes? Where we’re going, we don’t need lanes.
I know snow isn’t the same as rain. Our markers disappear in the rain as well.
Not car related, but my cousin broke up some abalone shells and spread them out along the path from the car spot to the house. Worked really well.
Nothing will come of this until someone invents a discrete nano device that incorporates a solar cell, a battery, and an LED (think of those solar pathway lights). Once you have that miracle device, they can just add them to transparent binder and voila, you have glowing paint. Solid state batteries will make this possible. The other parts already exist. These devices will be mixed with the glass beads which will really make those lines pop as they help radiate light in every direction.
I am not saying we are actually near it happening yet, but I am certain that they will one day be a reality.
There were experiments from the last few years about photovoltaic coatings to replace monocrystal solar cells. The problem is not only were they horrendously expensive (a combination of the precise structure during mixing and the precision needed during painting/coating) but the amount of power output only acted to increase efficiency of existing generation methods because it couldn’t produce enough power by itself to overcome losses. And this was still cheaper than shoving batteries and LEDs into everything per square inch for things that can’t receive maintenance.
Atari Night Driver IRL!
Despite the intervening decades since I last thought of that game, I got an instant flashback to playing it on my 5th-grade buddy’s new 2600 that he received for Christmas. (I had no such luck, my parents thought that giving me quarters for the arcade was more than enough.)
I’ve ridden a glow-in-the-dark bike trail a few times in Bentonville. They basically mixed a bunch of glow bits in with the trail surface. The first time I visited I thought it wasn’t working because I couldn’t see any glow. It wasn’t until I shut off my lights for a couple of minutes and let my eyes adjust that I could even see it (which was cool and made the trail rideable at slow speeds with no lights).
I’m betting this has the same problem, even for areas that are outside the immediate throw of your headlights. Especially with modern headlights that like to create an obscenely bright pool of light right in front of you (presumably because people think their headlights are brighter if they’re blinding, even though that’s ultimately counterproductive).
Oh, so that’s why there are black strips on some roads. I had assumed they just painted over some old markings when they put down new ones, although now that I think about it if you can paint over the old ones with black you could do the same with white, so that makes no sense.
Bike Ninja!
I have startled people a couple of times on that trail when I ride up with no lights on. 🙂
How about we just use regular paint? Why do we need slippery and invisible when wet paint when our cars all have headlights?
Last winter was extremely wet here in Southern California. I was driving home in the rain, in early evenings between 6 and 9 pm. Well lit areas of Burbank, Sherman Oaks and Los Angeles. I could not see the lane lines on surface streets nor on the freeways. Reviewing my dashcam, and it wasn’t picking them up either. Paint alone does not work.
That kinda works when the paint is new. Eventually the paint wears down and isn’t as visible.
It also doesn’t work very well at night when it’s wet. The glare of headlights makes it hard to see the paint lines.