Andy Smith
Mine action specialist
Mined area marking systems



Humanitarian Demining

Marking systems

See also Marking Systems in the Global SOPs.

Demining relies on marking systems of one kind or another to:

1) define the area to be searched;

2) to show the division between the searched and unsearched area while work progresses;

3) to indicate exposed devices; and

4) to mark an area as ready to be 'released' when the work is completed

All marking systems can lead to safety issues when the marking is unclear, causes confusion or when it is less than robust.

This introduces common systems in use and is not intended to suggest that any one is best. My preferences are given in the Global SOPs.



In many cases original survey marking is limited to the noting of a Landmark and its relationship to a marked Benchmark from which the surveyor's drawn map leads the reader to Turning Points on the suspect area's perimeter. The turning points may be marked out with stakes or painted stones, have metal posts driven into the ground, or may be unmarked and rely on the demining group taking measurements and directions from the map. Mined-area warning signs may be positioned around the perimeter - and should be in areas that may be used by the public. The signs may be linked by wire or plastic tape, or may be hung on posts and trees.

In many countries NO WARNING SIGNS are erected as part of preliminary survey - and signs are only placed immediately before Technical Survey and search and clearance.

Various signs are used - usually with a skull and crossbones on them. Early ones were made of sheet metal, but corrugated plastic has been favoured for some years because of its low cost and weather resistance.

Large signs are sometimes used - the "hcr" sign is from Croatia, but they are more vulnerable to wind damage than smaller signs…

…unless the sign is framed and well supported, so expensive.

Signs placed when the mines were laid may not have the skull and crossbones symbol.

One problem with traditional skull and cross-bone signs is that they get stolen. In some areas, the signs are deliberately cut in half or holes made to make them less attractive.

But you still see them on the fronts of trucks and in the offices of Advisers and aid workers.

Apart from souvenirs, plastic mine signs may be attractive to local people who have few materials available to them. They have been used to patch leaking roofs..…

And used to make toys - such as the sail for this toy boat in Cambodia.

Children are perhaps the worst culprits - and legislation is unlikely to stop them.

In some countries, an attempt to make the mine-signs durable and less attractive to theft was made by casting them in concrete. This is in Namibia. A similar idea was used in Cambodia where the concrete signs were square boxes - and were often taken as building materials.

In Thailand, the sign and its post is cast in concrete, then painted. The reinforcing inside the concrete is bamboo, so reducing the chance of it being stolen for its metal reinforcing. Its irregular shape makes it unattractive to use as a building block. [Picture "Sakkie"]

Mine warning signs may also be painted onto walls - as with this sign in Angola.

Local people may also have improvised mined area signs. Some are durable, but others are unlikely to last long.

A warning sign has been chalked on the front of this train (not really visible, it reads simply "Mina").

It can be a problem when official or improvised signs last beyond their time of use or are moved. This can lead to people ignoring signs that it is vital that they should obey.

Improvised signs can be confusing and not only when mine awareness groups advise people to put a cut branch in the path close by. A cut branch may have many other meanings, of course.

This warning sign is made using part of an RPG - and is an improvised traffic cone. Large shell cases are frequently used for this purpose in battle areas.

Technical survey and clearance signs may also be painted onto available walls or stones - as this Bench Mark sign in Afghanistan shows. The problem with painting signs on buildings or large rocks is that they may need to be expunged at a later date - and this is not always done.

At the edge of this village, the Technical Survey Turning Point posts can be seen in the centre of the picture .

This picture shows wooden survey markers - and a painted red band on a tree (in the shadow behind).

Trees are frequently used because they have a semi-permanence.

The trouble with wooden markers used to mark a surveyed area is that they may not last as long as necessary.

They rot and are subject to insect attack.

Painted parts of trees can also fade and become overgrown. And even the plastic signs are subject to UV exposure and may fade…

And even when a sign does not fade, rot or get stolen - all warning signs can be rapidly overgrown and become invisible.

When a mined-area is fenced, it may not be clear which side to avoid - and if the fence was placed by those laying the mines, they may well have put mines on both sides to deter people from cutting the fence. Fences also fall into disrepair or get overgrown, of course.

A heavily overgrown minefield fence.

In this place, a single rusting strand of wire is all that was left of an original fence. And the Type-72 beside it could have been missed.

In this picture a single strand of barbed wire curving downward is just visible amid new growth. This is not a very clear sign for the general public.

Surveyed areas may be marked with plastic tape and sticks - but this can lead to confusion about which side of the marking is the safe side. The building is clearly not to be entered - but which side of the tape around the scrap metal is safe? Plastic tape is also easily broken and can be moved around by wind. I have found lengths of mine-warning tape blowing around on roads many times.

As well as for survey and permanent markers, painted stones are also used to mark the extent of mined or cleared areas. In this picture, the surveyors cut a path through the mined area and marked it with red stones.

This shows the Start point and rows of painted stones. The other painted stones on the right, apparently randomly placed may be confusing.

Confusion may be especially bad when there a lot of other stones around. There have been accidents when the stones have been accidentally or deliberately moved. The red metal flag marks a place where a mine has been found.

Even when the stones are in tidy piles, it can be hard to determine where it is safe to walk. This raises the question of whether signs marking the divide between searched unsearched areas are exclusively for the deminers, or also for the general public. If the latter, the potential for confusion should be addressed.

Some groups, in this case a technical survey team in Afghanistan, use stones but prefer to use flags whenever possible.

Rock marking systems are also used in other countries, presumably because those in charge were familiar with them.

The unchecked area around this flail in Eritrea is confusingly marked with rocks painted red and white. The absence of a "line" marked by string or tape can make it hard to see exactly which area is safe.

Marking the cleared area with painted stones is also common in areas where the stones have to be brought in. The painted white stones around this partly cleared pylon in Afghanistan are an example. There was an accident at the pylon and work stopped, and the edge of the searched area was marked by a ridge of earth. The marking is low-cost and convenient, but it is not always clear where it is safe to go - and may be very unclear to the general public.

Stones may also be used in combination with sticks and string or tape, as this picture from Somalia shows.

During clearance, wooden sticks and tape are frequently used. The stakes are of varied lengths and painted various colours to serve different purposes - such as marking where a device was found and has now been cleared.

Some groups use tape or string to join wooden posts - but they may do so sparingly.

Sometimes the tape is taut, others slack.

Sometimes the support sticks are close together….

Sometimes far apart. In this example, mine tape has been used to join poles over long stretches and a breaching lane is marked entirely with red-topped posts with no tape at all.

In this mined area, white tape is used to mark both the perimeter and the clearance lanes. The perimeter posts are longer than those used in the lanes.

The same tape may be used to mark out dog "boxes" as in this area which was previously flailed and the safe-lanes searched and cleared manually.

Often the string or tape used in a search lane is paid out as the deminer works and may have no interim supports. This means that a lane always LOOKS straight, no matter how much the deminer may have moved from side to side, and leads to a higher risk of leaving missed hazards behind.

The rolls of tape used to mark a clearance lane in this mined area are made of canvas and are far more robust than plastic tape.

The working area inside the lane is marked by one or two sticks - in this case two.

Stones sticks or painted wooden cubes are used to mark metal detector indications in some places.

When a mine has been discovered, markers are often placed to show the spot prior to the device being destroyed or removed. These are often collapsible cones. Colours vary - and are usually brighter than this version from Cambodia.

In this case, also in Cambodia, the marker is cut from a mine warning sign.

A painted metal flag and a cloth flag are also used.

A painted metal flag marking an exposed PMD-6.

Here marker triangles are cut from sheet metal with red tape on the end.

Here, a triangular marker points towards the device, and a collapsible red "box" is visible from farther away.

There are great many variations, but most are visible from some way away.

Other markers are meant to be more permanent.

This is a concrete survey turning point marker cast into the ground.

After an area has been searched and cleared, permanent markers are supposed to be placed so that the extent of the area is always clearly known. This is not always done, and when it is done by putting metal into the ground so that the metal can be found with a metal-detector later, it is sometimes 'lost' or the metal may be stolen. This picture shows a permanent survey mark. The concrete contains metal, and written details are also cast into the concrete. If reinforcing bar or other metal with a resale value is used, even these durable markers may be dug up by children. When the area is wanted for agricultural purposes, the farmers may remove the markers because they get in their way.

These are permanent survey markers used in Thailand. One shows the Start Point, the others a Turning Point. In this case a combination of temporary and permanent survey markers are used.

This is a Turning Point stencilled onto a corrugated plastic sign from the same demining group.


  • There is no single integrated system using the same method and materials for survey, mined area marking, marking during search and clearance and permanent marking.
  • All marking systems can fail due to failure of their materials, inadequate placement or misuse by the public.
  • Improvised systems can be especially misleading.
  • Improvised systems often provide the ONLY warning signs prior to the arrival of search and clearance deminers.
Bullet 4 is not in compliance with IMAS - but it is true. The failure to place perimeter warning signs in many countries ignores the needs of the civilian population. Exceptions occur in countries such as Croatia where legislation requires marking, and both perimeter marking and wire-fencing of areas believed to be hazardous is taken seriously.

    Accident statistics

    No data is available for civilian injury as a result of an inadequate marking system. However, some deminer data is available. From the Database of Demining Accidents:

    1) Inadequate area-marking is cited as a possible contributory factor in 10.5% of accidents involving deminers.

    2) 18% of all deminer accidents are classed as missed-mine incidents. In 23% of these missed-mine accidents, inadequate-area marking played a part.

    From this one can infer that improved marking systems during search and clearance would enhance deminer safety.

    Anecdotal evidence and common sense allow me to infer that many civilian accidents occur because the victims do not know they are in a dangerous situation - and so any perimeter marking of suspect areas during Survey could have a positive effect on civilian injury numbers despite the fact that the prohibited area would probably always be larger than strictly necessary. That said, in some places marking an area may encourage young men to enter it (young men frequently interact with explosive hazards quite deliberately), so marking could result in more civilian casualties. Well conducted Explosive Hazards Risk Education (EHRE) can be as effective in preventing civilian injury as area marking, so the EHRE should be conducted whenever an area is marked and left to be searched later.

    Return to Introducing demining.