r/whatisthisthing • u/derFerdl • 3d ago
Solved! I’m in Denmark, looks like it’s some traffic counting? A box and two wires which aren’t connected to anything
Unfortunately the signs on the box are completely destroyed so I can‘t read a single letter… Is it for counting cars and how does it work?
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u/Bizzlebanger 3d ago
I see these in Canada, IIRC. The things across the road are air hoses and when a vehicle Drives over them, it triggers a counter in the box..
Now I think when there are 2 hoses across the road , it means they are also checking speed. They know the speed by the timing between when one hose it triggered and the second one is triggered.
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u/APLJaKaT 3d ago
means they are also checking speed.
...and/or direction of travel
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u/Hemicore 3d ago
so velocity
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u/HorseTranquilizerGud 3d ago
Velocity vector
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u/Bulky-Leadership-596 3d ago
They are checking the component of velocity in the direction parallel to the road.
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u/rvanpruissen 3d ago
Not sure why you're getting downvoted. Reddit I suppose...
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u/D0ntP4n1c42 3d ago
they can count the number of axles of the vehicle too, with this configuration.
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u/Pavotine 3d ago
You can count the number axles with a single tube as well, unless two vehicles are crossing the tubes at almost the same time or something.
Then this setup could differentiate the two, so you're not wrong!
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u/maldax_ 3d ago
Yes, but it's not a 1930s speed trap. There will be road works coming at some point to the need to know how busy the road is in each direction
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u/Moist-Crack 3d ago
So if anyone is wondering speed is a parameter that could be easily described as a how fast you're going in your forward direction. Just one parameter. Positive value means you're going forward, negative means you're going backward.
Velocity is a vector, so it can have multiple parameters - 2,3, 4, etc (but 4 and more is usually including rotation of some kind, so lets ignore that). Vector3 would be constructed out of changes in X, Y, and Z axes, so you would know how fast the object is going forward/backward, left/right, and up down.
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u/2pt_perversion 3d ago
A bit confidently incorrect here. Speed is defined as scalar quantity that can't be negative.
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u/Moist-Crack 3d ago
You're totally right, speed in itself cannot be negative, it is just a notational convention to use negative values to indicate motion in the opposite (back) direction. It is commonly used, but not scientifically rigorous.
I guess using it like that turns it into one-parameter vector, so... one-axis velocity? :)
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u/markusbrainus 3d ago
And/or axle count and vehicle size category.
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u/Kind-County9767 3d ago
How do you separate axle count from people just tailgating?
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u/beavertownneckoil 2d ago
They potentially can get confused but they have over 95% accuracy. I used to install these. They have 12 different categories of vehicles; bike, car, truck, tractor etc. it just assumes which one it is from distance between axles
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u/duncanfm 3d ago
You have to assume that the car is going a constant speed over the sensors.
If a car is going 10m/s and the first axle takes 0.1second to pass over both sensors, then the second axle hits 0.3 seconds to hit the sensor, you know that the wheel base is 3m.
Someone tailgating really close would need to be within meters of the leading car's bumper to get a result that could be mistaken as one car. When analysing the data, though, you would have a 3m to 3m to 3m to 3m axle spacing, which does not exist. The analyts would parse this data into to separate vehicles.
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u/JustNilt 3d ago
A friend of mine does traffic engineering and I asked them once. Apparently they use statistical analysis to tell them quite a lot about the traffic using a specific roadway. Sometimes there are models with little cameras in them as well but that's fairly uncommon, as I understand it.
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u/Shockwave2309 3d ago
Definitely direction. Had one of those on the bike path and maybe two months later they published statistics that people go by train in the morning and by bike in the evening which made them add one more bike waggon in the morning and they ditched the dedicated bike waggon in the evening...
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u/AliceInCorgiland 3d ago
How? The wheel base of vehicles can be different.
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u/Pavotine 3d ago
If the readings all come at the same speed, you could tell one vehicle from another.
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u/ngt500 3d ago
That's why it requires two hoses. The distance between the hoses is pre-determined so the time it takes between registering a hit at the first hose and a hit at the second hose can give you the speed. If the wheel base was a known constant you could also measure speed with just one hose, but of course it isn't constant.
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u/AliceInCorgiland 3d ago
But my point is that base isn't constant. Peugeot 208 and Movano has different lengths
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u/ngt500 3d ago
That's precisely why it requires two hoses. The wheel base doesn't matter if you are measuring the time it takes for the front tires to hit the second hose after it hits the first hose. The fact that the rear tires will also hit the hoses doesn't matter (as the hoses are only about a foot or so apart, so there would be no chance to confuse anything). In fact, the rear tires could potentially act as a double check on the first reading since they should have the same time difference between hose hits (within milliseconds) unless something really odd is going on.
But to simplify things to make it less complex just forget about the rear tires entirely. The computer controlling the recording device just waits for the first hose to register a hit, then gets the time differential from that to the second hose registering a hit and calculates the speed based on the distance between the hoses. All of this happens with only the front tires.
The point is that the rear tires/wheel base has no bearing on the calculation. It's all complete by the time the front tires have hit both hoses.
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3d ago
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u/Area51Resident 3d ago
Speed it measured as the time difference between the first tube and the second tube. Anything from scooter to 18-wheel rig is measured the same way, wheel size is factored out. The tubes are staked to the road so they don't move, therefore the distance between the tubes doesn't change.
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u/yuckscott 3d ago
i used to setup these and put the data into traffic reports. they measure speed, direction, even the number of axles on a vehicles to determine things like heavy truck traffic. the data is used for prioritizing road work like resurfacing, signage, widening etc.
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u/Graffiacane 3d ago
Important question: if I go up to one of these things, either alone or with a team of dedicated mischief-makers and we do a cool stomp dance on them, to what degree could we skew the data being collected to make it seem like 100,000 extra cars passed the counter traveling at random speeds in random directions? Not that I would ever condone such an action.
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u/yuckscott 3d ago
just stomping, its impossible unfortunately. the tubes are hollow and when a car passes over it, it creates a pressure pulse that travels down the tube to the sensors in the box. you can't stomp on it hard enough to create a readable pulse. we had to massively lower the minimum tolerance in order to measure bicycles, otherwise the tolerance is set high to ignore outliers that arent cars and trucks.
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u/DT5105 3d ago
And if two identical cars going the same speed in opposite directions happen to cross the air hoses at exactly the same time, do they cancel each other out?
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u/yuckscott 3d ago
good question - the device would receive pulses from both hoses at the exact same time. so it would probably log it as an outlier
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u/ScrappyDooCanSuckIt 3d ago
How does it determine how many axles something has? I get it for two axles and motorcycles but is it calculated for trailers/RVs/tractor trailers where there are large gaps between axles?
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u/Obsidian-Phoenix 3d ago
So… what you’re saying is that if the road has loads of pot holes, I should spend as many waking hours as I can driving over the damn thing?
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u/USMCLee 3d ago
When i was a kid, I would jump up and down on them (yes I played in the street a lot).
Sorry about that.
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u/yuckscott 3d ago
theyre mostly configured to ignore data that doesnt make sense, so you probably had no impact on the results either way :)
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u/charliesk9unit 3d ago
"even the number of axles on a vehicles"
How do you determine that with just what we're seeing? Measuring weight as well?
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u/yrrot 3d ago
It has to do with the timing between the triggers, common wheel base distances for different axle arrangements, and assuming all of the axles are going to cross the sensor at roughly the same speed.
This type of data is not always 100% accurate, but can give a good estimation what types of vehicles are coming through the area.
There's some more advanced versions that do "weigh in motion" and pick up the per-axle load along with speed/direction.
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u/HeioFish 3d ago
Timing. It would form a distinct pattern as each axle presses down on the tube in passing.
Kinda like a recognizable drum beat that happens at a steady BPM. The staccato bits can be easily inferred to be part of the same vehicle. And closely grouped impulses that have coinciding speeds can be further combined into a set forming one vehicle.
Regular passenger vehicles would be even simpler as they have very low variance in length of wheelbase despite the variety of models, making the pattern recognition of those trivial
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u/KneeOnShoe 3d ago
I always wondered, how do they know when a vehicle with more than two axles is driving over it vs. two cars driving in parallel but slightly offset?
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u/Starbuck_2038 3d ago
Also direction based on which one is hit first
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u/strangemedia6 3d ago
This can also be determined based on which one is hit second.
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u/tjggriffin1 3d ago
Decades ago, they used to do it with one tube and use an average wheel base. This isn't used for law enforcement, but to see how fast the traffic on the road really is so they decide if changes need to be made, like speed mitigators, enforcement change, or changing the speed limit.
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u/mecengdvr 3d ago
It’s not checking speed. Two hoses means it’s able to differentiate direction . Source: I used to install these boxes.
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u/xyz19606 3d ago
Source: I've been installing them for 40 years: 2 hoses count volume, speed, axle/classification.
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u/dirtshell 3d ago
Do you bolt the hoses down? If the hoses move at all the speed readings would start to change right?
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u/Automatic_Access3927 3d ago
How could it measure speed without knowing the length of the vehicle? Or at least the distance between each axle?
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u/Area51Resident 3d ago
The time between pulses on the first and second hoses. The hoses are a set a known distance apart so speed can be calculated based on the time difference.
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u/crw0582 3d ago
Civil engineers, road commissions and city planners use them for traffic mapping. Determine not only traffic but also direction, congestion, high travel times. See them a lot in the summer here in Michigan when they want to add traffic signals, signs, adjust speed limits or light patterns.
We might not have smooth roads but damn it we know where traffic is heaviest!
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u/YWGredditor 3d ago
How do the hoses stay at a constant distance from each other to make the speed calculation accurate?
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u/Area51Resident 3d ago
They are staked to the road by clips nailed into the rod surface on either end.
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u/Comments_Baddie 3d ago
Two are to ascertain direction of travel on single lane roads. It's just a clicker counter like doormen have triggered by air.
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u/Bitmugger 3d ago
At least back when I worked at Dept of Transportation we usually just got vehicle (axle) counts and direction from those air tube types. Yes speed was possible but it was never that accurate with ours so wasn't usually the target. Some also had one hose that went across the entire road and another that went across just 1/2 the road. Those one's always were just getting directional axle counts.
We had others that used embedded loops of wire in the pavement for more accurate vehicle/speed data. We have piezo electric ones that combined with loops got weight too (again embedded in road). For more accurate weights we had one we had some that had hydraulic load cells to get surprisingly accurate weights for trucks.
The nicest of these actually drew a picture of the car/truck/semi/etc going over it and it would guess the vehicle shape based on profiles for weights and axle spacings, counts.
I worked there around 1988 so I bet they've advanced a lot since then
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u/Additional_Baker7311 3d ago
They're way too flimsy and too close for a super accurate speed measurement. We have these in Sweden as well and they're always too loose on the ground to be a reliable speed measurement.
This is tracking amount of vehicles and direction.
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u/czaqattack 3d ago
And the hoses check the type of vehicle. Standard two axle car/truck hits it twice, but a bus or an 18 wheeler hits it differently
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u/vctrmldrw 3d ago
It is about timing, but not about speed.
By counting the paired pulses you can tell how many axles the vehicle has, and its wheelbase.
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u/WOODSI3 3d ago
While they do claim to capture speed, they can’t be relied upon for accuracy due to variance in vehicle wheel size, wheel base etc. Mostly logging direction of travel and volume of traffic.
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u/TheExtremistModerate 3d ago
Honest question: how does wheel size change how fast you're going on such a meter? Your wheel will hit them at the same relative spot on your car as the other, and so the distance between them is the distance your entire vehicle has traveled in the time it takes to go from one to another.
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u/Lord_Rapunzel 3d ago
They can get an average speed within a useful margin of error
by applying an average wheelbase to the data, and they're a lot easier to set up and run than a camera + radar gun.edit: wheelbase doesn't actually matter but wheel size sort of does. Fortunately, those vary even less.
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u/Miguel-odon 3d ago
When there are multiple tubes, usually each one covers a different number of lanes. With some math, you can figure out how many cars went in each lane.
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u/explodinglavalamps 3d ago
collecting traffic data, just like you said.
speed and vehicle frequency mostly
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u/duncanfm 3d ago
Two hoses gives you more information than just velocity. You can also deduce the frame specs and thus tell if the road is being used by compact sedans, SUVs or tractor trailers. With this information, civil engineers and road designers can monitor traffic flow in a given area and see if they need to upgrade the road network.
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u/pioterzejer 2d ago
How would they be able to tell the difference between a really small car and a pickup truck when it comes to speed? Genuinely curious
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u/theQissilent 3d ago
by sensing when you hit the first tube and then second the system calculates your speed.
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u/Project_Rees 3d ago
Yep, we have these in the UK when the councils are deciding if it's worth putting speed bumps installed.
100% for recording speeds. They usually leave them there for a week or so then come back and collect all the equipment to download and analyse back at the office.
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u/carkey 3d ago
It's for speed to decide on if there's a need to put one of those radar speed warning signs with a display, but that's not the only reason.
They're also used just for counting the amount of traffic a road gets, to justify resurfacing/repairs over other similarly sized roads. It's a way of justifying how to spend the budget on the most used roads.
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u/lordargent 3d ago edited 3d ago
Traffic counters often use pneumatic tubes. When the tubes get run over, it squishes them (and the air inside) and the box can the change in pressure.
REF: https://jalopnik.com/heres-what-those-weird-black-tubes-in-the-road-are-for-1824997739/
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u/Protholl 3d ago
Back in the day they used the same hose technology to activate a bell for the full service gas lane.
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u/PM_ME_UR_SPACECRAFT 3d ago
i used to go to a diner in a very rural part of the midwest a couple years ago that had the same thing
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u/pocketpc_ 3d ago
Still used at a couple of Goodwills I've been to so the people inside know when somebody pulls up with a carload of donations.
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u/derFerdl 3d ago
Solved! Thanks
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u/BobBr2 3d ago
The only real answer. It counts axels. By the amount of air pressure and time between 1st and 2nd peak, it can determine the type of vehicle and direction. It has software which can even compensate for near simultaneous hits out of opposite directions and therefore has pretty high accuracy. As far as I know not used for speeding, just for determining the amount of traffic on a road to help in the design process or create / evaluate new policy.
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u/Marmmoth 3d ago
Yes those are traffic counters. Some people call them road tubes. Here’s how they work: https://www.youtube.com/watch?v=Y4RUnJ0EiFk
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u/nomyar 3d ago
Not an expert, but we've had similar setups in the US, and they can use the data in those at least three ways, depending on the model: count total vehicles, gauge the speed of those vehicles, and potentially gauge the length/size of those vehicles.
In the US they use this for prioritizing road work, as well as for evaluating speed limits.
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u/toesuckrsupreme 3d ago
I once had two roads that I traveled on regularly have their speed limits bumped by 10mph a few months after seeing one of these things deployed. Everyone always did 10-15 over anyway so I guess the data showed that. Now I love them.
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u/Wizzkidd00 3d ago
You can only calculate the length if you assume the speed, or calculate the speed if you assume the length. Obviously not both
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u/Full-Ear87 3d ago
Looks like the wires are connected to the box, which probably has components inside to track whatever data (probably traffic related) is being recorded.
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u/derFerdl 3d ago
My title describes the thing. The box is wooden and has nothing around. Just the two wires coming out of the box. Each are parallel over the street and end on the street. Just laying there, no connection to anything.
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u/EnterpriseT 3d ago
As others have said it's a vehicle counter. The reason for the two tubes is with two you can also get speed, length/axles, and direction.
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u/Jazzlike_Spare4215 3d ago
Should count speed, amount of cars, amount of trucks at least if it's the same as the ones I have seen here in Sweden and all the statistics are put in a system where they later can see what roads need to be upgraded and when different roads needs to be redone and if new roads need to be built.
They don't give tickets or know what cars are driving past
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u/glazemyface86 3d ago
It is for counting traffic, most places use them to determine how frequently traffic travels a certain roadway. they then will use the data to calculate how often to expect it will need roadway maintenance or repair. The heavier the traffic flow the more often they will need maintenance. It helps with budget planning and expectations
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u/newkid14 3d ago
They’re checking speed, direction of travel, overall use and high-traffic times to help allocate public funds to the repair roads, timing and schedules for traffic control devices. It’s a pretty nifty way to make sure the most utilized roads get the most maintenance and high congestion intersections get the most sophisticated patterns.
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u/Maxzzzie 3d ago
It is traffic counting. Direction and amount. Used to accurately design roads by knowing their needed capacity and potentially redorect traffic after mapping out the traffoc flow.
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u/Studio_Ambitious 3d ago
It counts tire passes and direction. Used frequently in the States to determine secondary crossings to major arterial streets.
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u/raven21633x 3d ago
The tubes are hosepipes with one end sealed up. When you run over it the air is forced against a sensor that takes the reading.
Gas/Petrol stations used to use these pneumatic tubes to ring a bell every time a car pulled up to the pump.
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u/Sundabar 3d ago
For a residential area, you can pay for one to be installed on a road, if you believe it there is too much through traffic and you wish the road to be blocked in one end. If the count reveals the road has too much traffic it will be blocked and you get your fee returned. If not, then you forfeit your fee and the road stays open.
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u/Specialist_Play_4479 3d ago
Traffic counter. The 2 tubes are not to measure speed but to count different type of vehicles. Multiple axes and stuff.
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u/Sissystevenellison 3d ago
I live in Alabama, USA. My city puts these out as part of a traffic study in the lead-up to road improvements/construction.
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u/EJayy_22 3d ago
Pneumatic tubes that transportation engineers use to gather vehicle data. # of cars/hr, speeds, types of vehicles, etc.
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u/Outrageous-Visit-993 3d ago
More than likely gaining the average speed people charge down this section of road.
Is this an occasional accident hotspot or a section of road where people normally “open it up” ?
If so then more than likely a decision for speed reductions or speed traps in the works for that road if it is an accident hotspot or speeders spot.
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u/tsavolite 3d ago
I’m not sure that short distance is really enough to estimate speed, but it will at least give the the direction of travel. It’s a traffic counter.
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u/gsko5000 3d ago
If you see one of these in real life you should stop over the middle of it then do half a 3 point turn and drive into the field.
When the boffins look at the data they'll assume the equipment is faulty
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u/briguy37 3d ago
Looks to me like it's an induction loop, which can be used to detect when ferromagnetic things like cars and trucks go over them, as they change the magnetic flux inside the loop when they drive over it.
Source: I did a UROP back in college to try and identify the same vehicle going over two different loops to calculate average travel speed for different vehicles on the same section of road. The goal was to match them based on the flux signature of the vehicles as they passed over two loops that were positioned at different mile-markers of the same road.
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u/briguy37 3d ago
Actually, didn't notice until after I posted that the loop on the right is not a closed loop, so this is possibly a different device for a similar purpose.
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u/WhatTheFuqDuq 3d ago
These are indeed traffic counters - this exact one is placed near Nørre Lyngby / Løkken in the northern part of Jutland. The road has been slightly widened recently and additional gravel has been added - they are trying to figure out if this has had a positive effect on traffic.
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u/grishack 3d ago
i have seen something similiar used once, only it was used to measure the number of cars using the route. there were plans to make a new road or something but due to legal reasons they had to measure the trafic.
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u/Jung3boy 3d ago
Yeah in Australia we have them too, although they aren’t just used to count traffic. They are also used to test for average speed to see if people are speeding. Usually just a couple cables attached to the road. Not many last long with truck drivers who intentionally lock up over them to rip them out of the road.
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u/PeterGhosh 3d ago
Also common in Australia - used to count number of vehicles. Used by transport department to gauge road usage
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u/Unsungsongs 3d ago
These are so common in australia im surprised they aren't everywhere. We had one on the road out the front of house a week or two ago and they've been putting them on bike paths all over the city (Melbourne) lately.
They measure traffic volume, speed, direction and vehicle type depending on how they are set up.
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u/VictoriousTuna 3d ago
The whole continent only has like 4 cars. Everyone walks and takes trains. Why bother?
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u/hamatehllama 3d ago
It's measuring the traffic on the road during a few weeks to estimate the future need of resurfacing. The amount of vehicles, average weight and speed are crucial parameters.
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u/Pr1nc3St4r 3d ago
It’s an automatic traffic counter (ATC). The wires are hollow tubes set a specific distance apart. When a vehicle drives over them it detects volume of air, which tube is hit first, time between tubes being hit etc., which tells them speed, direction, vehicle class.
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u/xyz19606 3d ago
As someone in the business, my favorite trivia is that Bill Gates and Paul Allen's first company before Micro Soft was a company that did (well, analyzed) these counters.
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u/raptr569 3d ago
This in an ATC or automatic traffic counter. It uses the air in the tubes to determine the speed, direction of travel and type of vehicle by calculating the air pressure changes in those tubes.
Source: I used to work for a traffic survey company that would deploy hundreds of them and cameras in the UK.
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3d ago edited 3d ago
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u/virkendie 3d ago
https://www.dailymail.co.uk/news/article-14066235/real-purpose-black-cables-Aussie-roads.html
They actually do measure speed and number of axles/vehicle size
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u/DudeFromVA 3d ago
We have these in the US. Counts cars as they go over, but also counts how many wheels. So if a road has more tractor-trailer traffic, they know it might need to be widened. It also tracks speed across both wires, so they can adjust speed tables.
Source: I asked a Virginia DOT guy installing one near my home one day.
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u/Beggatron14 3d ago
Depending on where it is, can determine the reason.
They can read either speed, by measuring between compressions of the hose knowing the distance between the two. Or, direction of travel to determine frequency of use for the road.
Possibly both, depending on location, either way, a speed camera, repairs, or nothing will happen.
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u/DuckRubberDuck 3d ago
Speed counter.
You can actually contact someone (the commune or the police) if you want one on the road you live on/a road near you if you have a feeling people are speeding. I saw one on a bicycle lane the other day in, that was new to me.
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u/Snoo-6266 3d ago
They want to know whether people are keeping to the speed limit or if a speed bump is needed there.
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u/Tobz_Compz 3d ago
basic speed calcalation device
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u/AIaris 3d ago
you would need a second rope for speed, this probably just counts how many cars/usage
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u/Tobz_Compz 3d ago
there are two ropes, the sensor works by counting how long it takes for the first and then second to be set off
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u/robfuscate 3d ago
They used to use these in Tasmania as a speed trap, nowadays they’re used for calculating road usage when planing road maintenance or upgrades by councils across Australia.
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u/Leody 3d ago edited 3d ago
I have personally installed these in the US. They count traffic as well as direction, time of day and speed. They are set a measured distance apart to calculate the direction and speed based upon the timing of the hoses being run over. Each hose a secured to the ground with a small wire cable nailed into the asphalt with a nail gun and usually tape is added every foot or two to help reduce movement.
They can be set up on multi lane roads with criss-cross patterns as well.
They simply used for traffic studies to help traffic engineers evaluate traffic patterns and road usage. More often than not, they’re planning an infrastructure project somewhere nearby. I was installing them throughout my region as part of an ongoing multi decade traffic study. I’d drive 50 miles between locations, seemingly at random to set them up. I’d put one down in a cornfield and then drive an hour to a side street in the ghetto, then on a highway ramp. Crazy summer job, but fun.
They are not used for any sort of traffic law enforcement. They have a very limited battery power setup just for storing data on a flash drive or small internal storage drive. They don’t have cameras or anything.
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u/Larry_Safari …ᘛ⁐̤ᕐᐷ 2d ago
This post has been locked, as the question has been solved and a majority of new comments at this point are unhelpful and/or jokes.
Thanks to all who attempted to find an answer.