Snow can make driving dangerous or downright impossible. It’s why municipalities spend huge sums on salting the roads and plowing them clear. In parts of Japan, though, there’s an entirely simpler solution to this wintery problem.
The “shosetsu” system, as it is known, is responsible for melting snow on the roads across much of Japan. It relies on sprinklers built into roadside barriers and the roads themselves. These deliver a slow trickle of warm groundwater to melt much of the typical snowfall seen in Japan.
It’s a tidy way for dealing with snow that requires no salt and no manual labor. Plus, thanks to Japan’s heavy rainfall, there’s plenty of groundwater to go around, and by virtue of the country’s volcanic geography, it’s usually pretty warm down there. For the same reason that Japan is covered in natural hot springs, it’s easy for authorities to find groundwaters at temperatures from 46 to 64°F. That’s more than warm enough to melt snow.
The system was first developed in the 1960s, when it was deployed in the city of Nagaoka. The technique proved viable, and soon spread across the rest of Japan. By 1977, there was a full 354 miles of shosetsu-equipped road, and uptake has continued from there.
It’s a unique solution for a country that deals with more snow than many. Walls of snow over 10-feet high are well-known in areas like Niigata Prefecture. It’s no surprise that Japan’s snowiest areas were quick to adopt groundwater road sprinklers soon after they were proven.
In light snowfall, the sprinklers can keep the road almost entirely clear.
The system isn’t necessarily perfect. Adding pipes and sprinklers to roads does increase construction costs, after all. It’s also not an ideal solution in extremely cold conditions; if the ground temperature is sub-freezing, there’s a risk that spraying water on the road will just create ice. However, by and large, the system works well, keeping roads and even footpaths largely clear during the winter snows.
This technique is still a rarity outside Japan, and there are reasons it isn’t more widely used around the world. Japan has lots of groundwater, and it’s hot. The country as a whole is quite geothermally warm, and that’s a big part of what makes the system work. Without warm groundwater, such a system quickly becomes inordinately expensive to operate, as it would require huge amounts of energy to heat the water supply.
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Indeed, the Chinese city of Harbin has experimented with its own snow-melting technology built into the roads. However, it wasn’t able to just pump warm groundwater into sprinklers. Instead, a heat pump is used to warm a fluid which is pumped through pipes embedded in the roads. To transfer heat into the fluid takes a lot of electricity, compared with Japan’s solution of just pumping already-warm groundwater up to the road surface.
Overall, Japan was able to develop a unique snow-melting technology that took advantage of the natural resources it has on hand. Sadly, it’s not a silver bullet for every snowy road out there. If you’re not in Japan, expect to suffer through many more seasons of plows and road salt in the winters to come.
Image credits: Daderot CC0, mdthib via YouTube screenshot, GoddersUK CC BY-SA 4.0
Neat.
in MN they use potassium acetate sprayers on some bridges.
This is a pretty cool (even if it’s localized) solution. I’m sure there are plenty in the comments pointing out how it wouldn’t work where they are. That was mentioned in the article already, y’all. Read the whole thing past the first paragraph and you’ll see.
Sir, this is the internet. We do not read, we just mindlessly comment.
So next time it snows I should turn the sprinklers on and aim them at the street. Got it.
Make sure all of your neighbors do so as well, so the entire street is nice and ready to go
Let me know where you live and I’ll open a shop selling sticks, pucks and skates.
We have these in Minnesota too, but we put them on ski hills and call them snowmakers. 😉
What’s actual air temperatures? This is cool, but in my area it would quickly get overwhelmed when it’s 10F outside… and make everything ice.
This is the question. I think this must be a rare perfect combination of circumstances. Speaking for the Deep South, if it’s cold enough for snow to be a problem on the roads, it’s cold enough to re-freeze this water really quickly.
But most of the time our snow events are a day or less, with air temps just below freezing, and ground temps at (or above freezing). If the refreezing risk is minimal, this makes sense.
No, it doesn’t. That’s a LOT of plumbing. I’ve still never met anyone with a sprinkler system in their yard who was like “Yeah, it’s given me years of trouble-free service and I’m glad I have it!” Now expand that by a few thousand times. Japan is amazing.
Much higher population density helps.
So where I lived in Japan we never had issues with frost laws like in Northern US. So many times the depth of the system wasn’t a huge impact. Where I lived though it was a combination the pumped groundwater and the initial clearing by snowmachines on heavy falls and the light falls usually the sprayers worked fine.
Every 2 years though there was a section of work being done on the sprinklers. Also with the design of Japanese roads outside of major cities there are no raised sidewalks but just a curb barrier so the water from the road would drain onto the drains in the walkway or you would have to walk on the roads to avoid the snow.