There are two different types of marker posts – aerial and boundary.
Aerial marker posts are designed so that anybody in the air or on the ground can clearly see them. They are roughly 2m tall and 100mm in diameter and made out of white recyclable plastic; their red top makes them hard to miss. Important contact information is posted on each marker.
It’s important for our engineers and survey teams to reference the route of a pipeline on the ground. To indicate where a pipeline changes direction, aerial marker points are positioned at significant intervals.
Aerial marker posts are usually located at one kilometre intervals along the route of a pipeline. Sometimes they are placed closer together, depending on the location and route of the pipeline.
Boundary marker posts are used at road, rail and waterway crossings. Their purpose is to provide information to those working in publicly accessible areas, but in close proximity to a pipeline.
At roughly 0.5m tall and 0.2m wide, they are smaller than aerial marker posts. Older boundary marker posts and those in urban areas are made of concrete. In open countryside locations, the markers are made of more sustainable, white recycled plastic.
Both posts have an orange faceplate to aid visibility, and also include our contact details.
Pipeline operators in the UK must comply with the requirements of The Pipeline Safety Regulations, 1996. These regulations require us to let people know where high-pressure gas pipelines are located.
The Institution of Gas Engineers and Managers has prepared specific guidelines (IGEM/TD/1) to help us meet these requirements.
The guidelines suggest that we place marker posts at suitable points such as field boundaries, crossings and changes in direction. They also advise that we consider placing markers that can be viewed from aircraft.
National Grid and other high-pressure gas pipeline operators, follow the IGEM/TD/1 standard.
We have marker posts to point out where there are underground pipelines and cables. These posts also help our engineers and survey teams locate pipelines and cables before carrying out checks on nearby sites.
We have over 12,000 kilometres of high-pressure gas pipelines across the UK, and our first order of business is to keep them safe and reliable. Excavation damage to any pipeline could have severe consequences.
While there have been very few critical incidents in the UK, the potential for serious injury and damage to high pressure pipelines drives National Grid, the Health and Safety Executive and other regulatory bodies, to implement precautions. Installing marker posts and regularly monitoring pipelines, helps to keep the public and our employees safe.
Industry guidelines mandate that we place marker posts at specific locations, such as changes in pipe direction, road crossings and areas with increased risk of damage. This guarantees visibility between posts, so anybody working near a pipeline can see its approximate route.
We use different types of marker posts for different purposes and situations.
Where possible, we can install the smaller post design. However, where pipelines run cross-country, smaller posts are not always appropriate as vegetation and crops can obscure them.
Our engineers and survey teams need to reference pipeline locations and work taking place nearby. In this instance, taller aerial maker posts help to locate pipelines from the air and on the ground.
While public safety is our top priority, we try to minimise the impact on the environment through thoughtful and appropriate use of marker posts.
Yes, our Plant Protection team can answer most questions about working with or near pipelines.
We’re currently adding our gas distribution network list to Linesearch (linesearch.org), a free online enquiry service for our National Transmission System.
We will also mark out the position of our pipelines for anyone working in the vicinity, free of charge.
The marker posts are a necessary additional safeguard against working in areas where there are buried pipelines or cables, since not everyone contacts us before they carry out work.
To ensure we’re doing our utmost to protect our pipelines and ensure public safety, we have a series of checks in place.
During their routine work, our operational staff liaises with landowners and look out for any threats to pipelines. We provide local planning authorities with pipeline maps, which prompts them to consult us about any proposed works near pipelines. We also give each local planning authority a booklet that describes how to work safely in the vicinity of our high-pressure pipelines.
Subject to flying restrictions, we aim to fly the route of every pipeline once every two weeks. We also walk the route of the National Transmission Pipelines once every four years, which is currently being extended to include our gas distribution network.
We provide free safety advice to anyone working in the vicinity of pipelines, and will mark out and monitor pipelines route free of charge. As pipelines do not always run in straight lines between marker posts, it’s important that you contact our plant protection team to identify their precise location.
Pipeline marker posts are essential for maintaining public safety. Although we’re fortunate that there have been few incidents, the risk of damage to pipelines and those working near them is always present.
We’re aware of instances in which people have come close to our pipelines, as well as the serious consequences caused by damage to pipelines in other countries.
Every year we see more than 10,000 cases in which excavation or building work takes place in the vicinity of our pipelines without any prior notification to our Plant Protection team. In 2012/13 there were more than 100 cases where there could have been significant damage to our pipelines had we had not spotted what was happening and intervened.
Marker posts are therefore an important and necessary safeguard, which help to avoid serious injury and pipeline damage.
The UK Onshore Pipeline Operators’ Association website (ukopa.co.uk) is a great resource, in particular the 2011 Report for the ‘UKOPA Infringement Database’.
The Major Accident Hazard Pipelines division of the Health & Safety Executive is also helpful (hse.gov.uk/pipelines/hseandpipelines.htm).
We need the markers to be visible to ensure public safety. The current high-visibility aerial marker posts were introduced following a tragedy in Belgium in 2004, in which 24 people died as a result of damage to a high-pressure pipeline.
No, they are also used by engineers and surveyors on the ground as a point of reference. Marker posts also remind people working near them that there is a buried pipeline close by.
While our helicopter pilots and observers use GPS mapping to locate the pipeline route, the observer also relies on the marker posts to provide a point of reference at ground level. This helps to determine how close work is taking place to a pipeline, and to prioritise how urgently we need to make contact with anyone working in the vicinity.
Our ground survey teams use aerial marker posts in a similar way. The posts provide crucial line of sight and help visually map the route of the pipeline.
We monitor the condition of the marker posts, and replace them as they become old, are damaged or go missing.
Most pipelines in the UK were installed under planning permission granted by town and county planning orders and under agreements with landowners to install, operate and maintain them. While planning permission isn’t needed to repair or renew equipment such as marker posts, we follow the Institute of Gas Engineers and Managers' guidelines when installing them and keep the number installed on any given pipeline to the necessary minimum.