Big white X's on the roads

[+g0t0pless]

First off, these are NOT marking train tracks, power lines, or anything else that I can figure out.

 

They are big giant white X's that span almost the entire lane of the road.

 

They were put there on purpose because they are perfect X's, not spray painted on by graffiti artists.

 

These are painted with the same reflective white paint used to paint the other lines on the roads.

 

There are about 6 of them that I pass every day on my way to work, over a 22 mile span.

 

Can anyone confirm why they exist?

 

By the way, these in PA, north of Pittsburgh.

[+scotte]

Survey markers.

[+NightPilot]

Markers for the bear in the air. Using those to measure known distances, with a stopwatch, it's easy to calculate the speed of a car. The bear in the car then gives you your ticket, and your radar detector never makes a peep.

[+Renegade Knight]

Markers for the bear in the air. Using those to measure known distances, with a stopwatch, it's easy to calculate the speed of a car. The bear in the car then gives you your ticket, and your radar detector never makes a peep.

If they were marking control points for an arial survey they would have some kind of survey marker in the middle (these may as well if they did use a surveyor to measure off an even distance). Plus the odds of them being in the middle of the lane are slim. In additinon the ones made for surveys are not normally made out of reflective paint and are smaller.

 

I'd say that NightPilot nailed this one.

[+tomfuller & Quill]

The markers are to show up on aerial photos. If the plane is too high the 2 marks on the photo will be too close on the photo. There are quite likely some plastic X's in some open areas nearby. Precise scale of a photo can be determined if the distance between the markers is known.

[+Metaphor]

And all this time, I've been digging them up, looking for the buried treasure underneath... go figure...

[Difficult Run]

Markers for the bear in the air. Using those to measure known distances, with a stopwatch, it's easy to calculate the speed of a car. The bear in the car then gives you your ticket, and your radar detector never makes a peep.

If they were marking control points for an arial survey they would have some kind of survey marker in the middle (these may as well if they did use a surveyor to measure off an even distance). Plus the odds of them being in the middle of the lane are slim. In additinon the ones made for surveys are not normally made out of reflective paint and are smaller.

 

I'd say that NightPilot nailed this one.

 

I'll give NightPilot points for imagination, but he's incorrect.

 

These large x's are set for horizontal control (lat/long) when doing aerial photographs.

It's not necessary to place a survey marker in the center of the "x", however, most of them do.

Generally, its a pk nail driven flush with the surface. (you see, not all survey markers are disks).

 

Besides, using a helicopter and a stopwatch is not only inaccurate, but impractical from a monetary standpoint.

[+g0t0pless]

I have a few problems with everyone's answers so far.

 

1: These X's are HUGE, like 10ft x 10ft I'd day. They span almost the entire width of a lane.

2: These X's aren't always on main roads. There are a few of them on back roads that are impossible to go any faster than 35MPH.

3: Not all of the X's are parallel with the road. A few of them are at an angle to the road.

4: A few of the X's are under trees, making it near impossible to see from an airplane.

5:There's 1 X in particular that is the middle of the road where there is no driving lane. It's placed in an area of diaganal yellow lines (like they have right before a turn-off lane at an interesection).

 

At first I thought they were to mark overhead wires for truck carrying oversize loads, but like I said, some of them are on backroads, and only a handful of them are near overhead wires.

 

I'll have to post some pics of thsse X's so everyone can see what I am referring to.

 

Any other guesses?

Edited April 8, 2007 by g0t0pless

[+Renegade Knight]

I have a few problems with everyone's answers so far.

 

1: These X's are HUGE, like 10ft x 10ft I'd day. They span almost the entire width of a lane.

2: These X's aren't always on main roads. There are a few of them on back roads that are impossible to go any faster than 35MPH.

3: Not all of the X's are parallel with the road. A few of them are at an angle to the road.

4: A few of the X's are under trees, making it near impossible to see from an airplane.

5:There's 1 X in particular that is the middle of the road where there is no driving lane. It's placed in an area of diaganal yellow lines (like they have right before a turn-off lane at an interesection).

 

At first I thought they were to mark overhead wires for truck carrying oversize loads, but like I said, some of them are on backroads, and only a handful of them are near overhead wires.

 

I'll have to post some pics of thsse X's so everyone can see what I am referring to.

 

Any other guesses?

 

Given your better information. I'm now in agreement it's for Arial Surveys. If they were marking the road for arial enforcment of speed they would be uniform on the road.

 

These X's serve two purposes that are related.

 

They give the surveyor a reference point/s to tie the airal photo to the survey coordinate system used in the area. They also give the surveyor the information needed to orthorectify the photo's so they can be used for mapping. Arial photo's are taken from a camera (Yeah I know duh!) that has a fixed reference point. The further away from "straight down" you get the more distorted the photo is. Plus the panaromic map is stitched together out of serveral photo's. If you have tried to make your own panaromic photo taking your own pictures and taping them together you have noticed the problem. They never quite line up right. Orthorectification lets them 'warp' the photo's so they are accurate.

Edited April 8, 2007 by Renegade Knight

[+Wayfinders]

They are aerial targets. The difference in size is relative to the height of the flight. Low level flights and photography are for more precise three dimensional mapping. Since the altitude of the plane is lower, the target can be smaller. For higher altitude flights the target obviously needs to be bigger to show up on the photograph. It's not easy, painting those big crosses on roadways. People will flatten your safety cones, run over your paint and threaten to sue without a bat of an eyelash anymore. Sad. I prefer to lay down tarpaper in a field and paint my white lines on that. That way after the photos are taken I can pick them up and leave no trace. The Surveyor provides the coordinates and elevation of the point to the aerial mapping company and they provide base mapping to the Surveyor.

I have heard that single horizontal lines across a road were used to time cars and determine speed by the police. This was probably true in the days before radar. Looking at aerial photographs, those lines these days seem to be there to mark the approach of airport runways.

[+d-town cachers]

as a surveyor myself, i'd have to go with survey markers also. although, the aerial targets (we call em chevrons here) that we use are more like a half-x, but i have seen full x's in use also. so yeah, i'm gonna have to go with aerial survey control.

[Zoptrop]

Similar question in the daily paper... someone saw a large X made of nylon held down with stakes and wondered what was up. Advice column lady stated:

 

That the road/highway department was using them for mapping. They said that the winter time was preferable (in Texas) since there was less vegetation and they could see the terrain better.

 

Some markings on the roads are sections of test strips where the highway department tries out different paints and adhesives to see how they hold up to weather, traffic, etc. The state has finally began putting up signs stating this so motorist won't freak out.

[+sylamore]

 

Some markings on the roads are sections of test strips where the highway department tries out different paints and adhesives to see how they hold up to weather, traffic, etc. The state has finally began putting up signs stating this so motorist won't freak out.

 

In AR and MO they are either X's or solid bars. Some are used to test various paints for durabilty, and are so marked by signs along the road. Others are used for speed enforcement. Check them next time you go over that area and see how far apart they are.

Scooter

[+g0t0pless]

 

Some markings on the roads are sections of test strips where the highway department tries out different paints and adhesives to see how they hold up to weather, traffic, etc. The state has finally began putting up signs stating this so motorist won't freak out.

 

In AR and MO they are either X's or solid bars. Some are used to test various paints for durabilty, and are so marked by signs along the road. Others are used for speed enforcement. Check them next time you go over that area and see how far apart they are.

Scooter

 

I doubt they are for speeders. The reason I say this is because no 2 are on the same road. There might be a few that are, but there are stops signs along the way in between them.

[Shiraz-mataz]

Hey g0t0pless, how about posting the coordinates of these markings so we can check 'em out in Google Maps...

[+McPhan]

Any sign of a roadrunner or coyote?

[+Wadcutter]

Hey g0t0pless, how about posting the coordinates of these markings so we can check 'em out in Google Maps...

They're aerial survey markers.

There is currently one at:

N39*51.319

W89*51.177

[+bflentje]

In Minnesota, I've seen them on highways, sidewalks, and even near sewage pumping stations.

There's a smaller X (about 5' across) on a sidewalk just a few blocks from my home.

[Zoptrop]

Or... they could be hobo signs (for really big hobos), or maybe they were left by "low men in yellow coats".

[PyroDave]

if they were on highways then they could be markings for a emergincy runway. The highways were actualy funded useing deffence funds. The idea was that if were ever invaded then streaches of highways could be used as makeshift airports for the millitary.

 

As for airial photos most of those markings are made out of white plastic and staked down in the servay area and removed after the fly over. I have seen a couple of these while takeing a GIS class.

 

Your best way of finding out what they realy are is to just call the local highway department and ask what they are.

 

Dave

[+dkwolf]

I have heard that single horizontal lines across a road were used to time cars and determine speed by the police. This was probably true in the days before radar. Looking at aerial photographs, those lines these days seem to be there to mark the approach of airport runways.

Around here, they still do aerial speed/traffic enforcement, but the paint markers are a solid stripe covering 3/4 a lane of travel, or on the shoulder of the road. Usually 1/4, 1/2, or 1 mile apart, and the pilot has a special stopwatch that he starts when you pass the first mark, and stops when you pass the second. The readout on the face is calibrated to show your speed, not the time.

 

And yes, friends of mine have been written up after being busted by the bear in the air.

[+Wadcutter]

Around here, they still do aerial speed/traffic enforcement, but the paint markers are a solid stripe covering 3/4 a lane of travel, or on the shoulder of the road. Usually 1/4, 1/2, or 1 mile apart, and the pilot has a special stopwatch that he starts when you pass the first mark, and stops when you pass the second. The readout on the face is calibrated to show your speed, not the time.

 

And yes, friends of mine have been written up after being busted by the bear in the air.

I worked a lot of "air speed" when I was a road Troop. Lines are a specific distance apart. I forget what it is now but it's a specific and constant number of feet. The pilot or the observer has a stop watch which they use to time the cars going thru the zone. They then refer to the chart which shows if the time is "X" then the speed is "Y". Pretty simple math. Traveling across a given location in a certain number of seconds takes a certain speed. The pilot then calls out the speed and vehicle description to the catch cars, follows the violator to the catch cars' location, and confirms the correct car when pulled over. "Air speed" as it was called was done at least weekly in my district and was done somewhere statewide everyday there was good flying weather. Use to get a bunch of speeders because it didn't matter if a person had a radar detector or not. The worst part of the detail was getting selected to be the observer on a hot, humid day. The pilot flies in a large oval banked pattern which gets pretty old very fast. Add in the heat and the constant bumpy ride and it doesn't take very long until you're ready to get out and walk.

Edited April 13, 2007 by Wadcutter

[J'nK]

Email the city and ask them. They will give you your answer.

[+Two Geeks and a GPS]

Around here, they still do aerial speed/traffic enforcement, but the paint markers are a solid stripe covering 3/4 a lane of travel, or on the shoulder of the road.

 

Same in Ohio, at least it was 15 years ago when I got busted that way on my way home from school......first day of having my license!!!!

[+Harry Dolphin]

Alien landing sites?

[+g0t0pless]

No way in hell these are to mark landing strips. There's trees all around, power lines all around, and none of them are on a straight stretch of road.

 

So far none of your suggestions have made any sense given the circumstances.

 

Remember:

 

No 2 X's are on the same road with a stop sign in bettween them.

Some are far apart while others are closer together.

Some are near trees (1 is even UNDER a tree).

Some are near power lines.

Not all of the X's are parallel with the road, some are at a slight angle.

There's 1 X that I know of that is NOT in the driving lane, it's in spot on the road that is yellow diagonal stripes.

[+WeightMan]

No way in hell these are to mark landing strips. There's trees all around, power lines all around, and none of them are on a straight stretch of road.

 

So far none of your suggestions have made any sense given the circumstances.

 

Remember:

 

No 2 X's are on the same road with a stop sign in bettween them.

Some are far apart while others are closer together.

Some are near trees (1 is even UNDER a tree).

Some are near power lines.

Not all of the X's are parallel with the road, some are at a slight angle.

There's 1 X that I know of that is NOT in the driving lane, it's in spot on the road that is yellow diagonal stripes.

Besides the fact that closed runways are marked with large Xs so that pilots will know NOT to land there.

[Difficult Run]

No way in hell these are to mark landing strips. There's trees all around, power lines all around, and none of them are on a straight stretch of road.

 

So far none of your suggestions have made any sense given the circumstances.

 

Remember:

 

No 2 X's are on the same road with a stop sign in bettween them.

Some are far apart while others are closer together.

Some are near trees (1 is even UNDER a tree).

Some are near power lines.

Not all of the X's are parallel with the road, some are at a slight angle.

There's 1 X that I know of that is NOT in the driving lane, it's in spot on the road that is yellow diagonal stripes.

I know from personal experience that the white x's that you are referring to are indeed survey marks.

But don't take my word for it. Try visiting these two websites.

 

"In order to get accurate aerial mapping it is required to set targets that will show up in the photographs. These targets are a large white “X’’ painted on paved surfaces, or a plastic or fabric “X” if placed on unpaved surfaces. " http://www.dot.state.mn.us/d4/newsrels/06/...rialMapping.htm

 

"Hi!, I'm Gary Waters Photo Lab Manager of Cooper Aerial Survey in Tucson, AZ, I'm looking for a solution to a unique problem associated to aerial images; that is, how to merge an image to mapping control coordinates. Perhaps you have seen those big white "X's" painted on the roads or off to the side of the road? Those X's are the mapping control points. It is my task to make a photo fit as best I can to those points by tilting, turning and twisting my easle." http://www.imaging-resource.com/IRNEWS/arc...0000324.htm#mai

 

If you still don't believe it, please call your county surveyor's office.

They will give you the same answer as I do!

 

By the way, it doesn't matter if those mysterious x-marks are under trees.

Most aerial surveys are taken in the early spring when the foliage is at a minimum.

 

Regards,

~ Mitch ~

[+Renegade Knight]

No way in hell these are to mark landing strips. There's trees all around, power lines all around, and none of them are on a straight stretch of road.

 

So far none of your suggestions have made any sense given the circumstances.

 

Remember:

 

No 2 X's are on the same road with a stop sign in bettween them.

Some are far apart while others are closer together.

Some are near trees (1 is even UNDER a tree).

Some are near power lines.

Not all of the X's are parallel with the road, some are at a slight angle.

There's 1 X that I know of that is NOT in the driving lane, it's in spot on the road that is yellow diagonal stripes.

 

You have four options.

Survey Markers for arial surveys. This has not been ruled out.

Marks for arial speed enforcment (not likley given the irregularity)

Pranks done for s***s n giggles.

Something nobody has heard of.

Edited April 18, 2007 by Renegade Knight

[+Vinny & Sue Team]

 

Some markings on the roads are sections of test strips where the highway department tries out different paints and adhesives to see how they hold up to weather, traffic, etc. The state has finally began putting up signs stating this so motorist won't freak out.

 

In AR and MO they are either X's or solid bars. Some are used to test various paints for durabilty, and are so marked by signs along the road. Others are used for speed enforcement. Check them next time you go over that area and see how far apart they are.

Scooter

 

I doubt they are for speeders. The reason I say this is because no 2 are on the same road. There might be a few that are, but there are stops signs along the way in between them.

Okay, since you are so keen to know the answer and so unwiling to acccept the pablum answers and vanilla whitewash which we have all been offering up, I am gonna go out on a limb and tell you a teensy weny bit more:

 

When I was in grad school at IUP in Indiana, PA (not far from the roads to which you have referred) in the early 1990s, a small part of my paid graduate assistantship duties involved assisting a professor in the graduate physics department with an off-campus "project" which also involved assistance from the graduate Geography department as well. The specialty of this particular physics professor was subquantum physics, and the project involved the possibility that extraterrestrial cultures might attempt to communicate with other intelliegent communications using certain little-examined principles of subquantum physics. The project did involve placing large white painted Xs on some roads. I am not free to say anything further; the project was largely funded by a government grant from a shadowy agency and I signed an NDA (non-disclosure agreement) which is in effect until January 2043.