Or you could call the local office of your state road department. I bet someone in the office knows what’s going on. Tell whoever answers the phone that you are wondering when the work is going to be finished and why they’re doing it in the first place.
Calling the road maintainence people or asking the workers takes all the fun out of guessing.
I agree with Chas123456789 that they are inserting sensors into the road. Exactly what for is the question. Smart highways? Congestion tolling? Any other ideas?
These grooves would be familiar to anyone in California, they are a common feature in California freeways. They are “anti-hydroplaning grooves” and are designed to give more traction during rainy conditions. The idea is that a tire driving over the grooves will force any standing water out through the grooves instead of building up in a “hydroplane” under the tire’s footprint. The tire remains in contact with the road rather than floating on a cushion of water. Plus, the grooves give an irregular surface which offers more grip to the tires, as opposed to a flat surface. And anyone who ever drove in the first rain after months of dry weather knows what happens to the road, all the dirt and oil comes up and it gets very slippery. California was the first state to groove their freeways as far as I know, mostly due to the unique weather conditions. The grooves are also commonly used in airport runways.
Upon closer inspection, I’ve noticed that these slots come in sets of six: one group of three ( ||| ) on the left side of the lane, and one group of three on the right side. They will usually go completely across the highway, a set of six in each lane.
However, in some spots they are in one lane only. Additionally, although the spacing across the road is consistant, the spacing down the road is not; in fact, they seem to be almost randomly spaced 10- 100 feet apart. If these slots contain sensors, which seems to be the best guess so far, the random pattern makes no sense.
Also, I’ve seen slots that have been in place about a year (ZenBeam: M14 east of Ann Arbor from Ford Road to just east of Gottfredson), and some of the concrete filler is breaking out, creating little rectangular potholes. To my mind, this is circumstantial evidence that these are not intended to increase highway durability.
And Chas, I don’t think these slots are “anti-hydroplaning grooves” because the slots are only about twelve inches long, and are not continuous, like the grooves are (we have those here, too).
In the absence of anyone’s interest in actually asking someone who might know (yep, takes all the fun out of our pretentious posturing and random guesswork), how about this one: these may be test strips for different mixtures of concrete. I know that I’ve traveled in places that told me (via road signs) that the next X miles would be a test roadway, and there followed several stretches of different types of paint across the roadbed, or there would be stretches of different textured roadbed. Since you report the “patches” coming out, this could indicate that they were not placed there in anticipation of permanence.
Here’s another WAG. They’re not sensors, but rather patterns that can be identified by an experimental optical recognition system on cars. Normally they will be about 100 ft apart, but on curves, they have to be closer together. And on approaching an offramp, they may only be in the lane(s) affected. Does this match their locations?
It also occured to me that the system may be using infrared light instead of visible light and that the concrete they put in may have a different IR signature than regular concrete. This would allow them to be used at night.
The white squates painted on UK raods are for use by the police.
Inside the patrol car there is a timer/measuring device which is used in 2 ways.(VASCAR)
First your patrol plod drives over the white square and sets the timer running while maintaining a steady speed limit rate of progress, then he will stop the device next to a landmark.This gives a time over that distance at the highest permitted speed.
The car then simply waits at a place where both the marker and the landmark can be seen and when a suspect vehicle is observed passing the whit mark the timer is started and it is stopped at the landmark. The equipment then gives a readout of the average speed - too much and you are nicked.
The other way is to follow a vehicle and use the white marker as the start point for the equipment which will then provide the average speed as soon as it is stopped.
The equiment is regarded as being more accurate than speedos and stopwatches and it is cheaper than the radar traps or speed cameras which have to be expensively maintained.
Here is a detailed history of the highway (M-14) in question. I had no idea anyone would be so fanatical about highways… but there it is.
And here’s the project site for the work on M-14 published by the Michigan Department of Transportation which lists the following contacts:
So how about it Zut? Are you going to do the follow up for us or do I have to compile this thread and send it to MDOT for the, ahem, “Straight Dope”?
Dystopos - now you’ve gone and wrecked a perfectly ridiculous conversation among a bunch of people with no knowledge of a topic, and no significant outside life. We were happy and content to babble endlessly about this topic, prattling on and on about possible reasons and potential effects, etc. And you go and throw a wet blanket on the whole affair by providing a source where any idiot can go and look for an answer. What’s this BBS coming to, anyway? THAT’S what’s wrong with America, I’ll tell ya. Guys sticking their two cents worth in, making things easier, better, cheaper. Why when I was a kid, we walked 5 miles to school, and we knew the value of a dollar. etc.
I, too, have pondered upon this relentlessly (though not enough to actually call NoDak DOT). I drive a semi and have seen this in almost every state.
1: The grooves are put in right after the new surface is laid. So it’s not a repair.
2: They usually stretch for a few miles, so can’t be sensors. If you wanted to measure load wieght, speed, density, etc. you would only need a few.
3: Since they are placed in the area of where the tires contact, I was interested in the idea of traction, but then why are the areas few and far between?
4: They definately aren’t rumble strips, they run as smooth as other surfaces that somehow don’t cause these time-consuming discussions.
Fear not teeming millions. I will call NDDOT in the morning and report back on what they are.
BTW,I was also intrigued by the idea that they’re testing new concrete mixes, but the why would so many states be doing it? Only reason I can think of is somehow using the area and climate as controls, or we can blame the AFL-CIO so coming up with a way to keep these guys employed at upwards of $20/hr.
Strange, what comes up in my mind is breather joints–to prevent cracks in high stress areas of the roadway. Other than that i’m stumped.
Dystopos:
Beat ya to it. Following up on suggestions above, I overcame my natural laziness and emailed a polite enquiry to MDOT about this subject. We will see if, and how quickly, they respond. I’ll try the phone route in a few days if I don’t hear from them. Naturally, I’ll let y’all know about whatever I find.
wastelands:
Nice to see someone else noticed this, and in multiple places, too. Please let us know if you find anything.
Here is a semi-WAG. My boss has done a lot of transportation related (mostly vehicular) consulting over the years, so knows his highways. Unfortunately, I couldn’t just walk him over to my monitor and point out this thread for obvious reasons. (I don’t spend any real time here during the day, but it would just look bad.) (Honest!) So I had to ask him without having the thread’s details to refer to.
His response concurs with many of the previous posts - most likely they are for sensors. He described it as a part of Intelligent Traffic Systems (ITS - he is going to lend me one of his reference books on the subject. Should be pretty interesting to look inside the mind of a stoplight.) In response to their being haphazardly placed, he says that there are many reasons to put sensors in the road. Some can respond back to a central office so civil engineers can get information on the highways. A change in overall speed at a particular stretch can tell you about the health of that section - not necessarily of accidents, but of road wear as well. They also need to keep records of highway volume for Federal funds and to comply with various state and Federal regulations. An apparently random placing of sensors actually comply with some relatively complex formulas as to required placement. (I could explain the statistical analysis, but I choose not to. Sure.) Lastly, many highways have sensors that report traffic information (speed, volume, etc.) to signals around exit ramps. A large volume of cars slowing down for an exit would trigger the lights at and around the ramp to react accordingly. Due to speed of traffic flow on a highway and the necessary lead time needed for the lights to react (it only seems that they go red instantaneously) they are not placed directly in front of the ramp, so the ramp / sensor connection may not be obvious. So some of the sensors may be there to monitor traffic in general, some may be there to comply with regs (they have to monitor traffic levels for noise, air pollution, etc.) and some may be part of traffic control. Put them all together and seeing a connection at 65 MPH might not be so easy.
Also, as to their placement on the road. A car does not need to drive right over them to register. Big chunk of metal moving through a magnetic field…
Now I have to get back to work, because I don’t really lurk on the board while I am at work. Honest!
Rhythmdvl
Excellent! Thanks for the research, Rhythmdvl. I think your description explains all the features of these “slots” in the road. So, even though you call it a semi-WAG, it ranks high on the plausibility scale.
[dons tin hat whilst awaiting answer]
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- I’m really bored.
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- I will guess: there is a pipeline of some sort underneath the highway and they are testing for a leak (or contamination by whatever’s supposed to stay inside the pipe) at each hole. Didn’t Cecil say something on this? - MC
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Here is what I got in an e-mail from Brenda Peek of MDOT:
Far be it from me to second guess someone from the DOT, but are these transverse cracks perfectly perpendicular to the traffic flow? I guess if that’s the case, then the answer makes a bit of sense. It’s a sort of repair job over some cracks in the road. Ok, fair enough.
I cut and pasted the message, so it’s not my fault that the word “stabalize” shows up.
Huh. Honestly, Bob, I’m scratching my head over that one. A lot of the places (but not all) I’ve seen these have the slots side by side in the same place across all lanes. I always thought lanes were laid down individually, and thus cracks would not propagate from lane to lane. Plus, as CC pointed out, having a crack perfectly perpendicular to the traffic flow seems unlikely.
I know Brenda speaks with authority, but dammit! her answer is intellectually unsatisfying.
(Thanks for following up with MDOT, though. We’ll see if I get the same info from my request.)