Movement Monitoring Surveys

A fixed position monitoring survey is the method of monitoring a set location on a wall / structure and observing movement in the horizontal and vertical planes over time. 

Fixed position monitoring is used for a number of projects ranging from small basement projects to large infrastructure projects such Crossrail tunnel project under London.

The monitoring project always starts with the initial setup of the monitoring targets and local survey control network. The targets are fixed to the structure in the pre-designated locations utilising either glue or drilled screws.

Without a fixed monitoring point to resurvey each time, the consistency will be poor or non-existent. Fixed points are installed on to the structure and usually consist of survey prisms or reflective target stickers. When using prisms, they are typically secured using screws drilled into walls or using high strength glue.

A local survey control network also needs to be installed. This involves placing survey targets (prisms or reflective survey points) away from the site. These are used by the total station as a way of calculating its precise position each time a monitoring survey needs to be undertaken.

A monitoring survey is undertaken using a piece of equipment called a total station. A total station is a high accuracy optical instrument that is used to measure distances and angles. Total stations are usually mounted on tripod legs, whereby the operator can look through the lens and record survey points. In some cases, automation is required If so a total station can be left in a safe location and operated remotely.

At each survey interval, the total station has to be set up using the local control network. Once set up accurately, the monitoring survey process can be undertaken. Each monitoring point is precisely surveyed using the total station and recorded to the instrument.

Once this data has been reached the office, it is uploaded to the monitoring survey software, which can generate data to illustrate movement (or lack of) over time.

A monitoring survey process is usually undertaken on the advice of a professional, such as a Structural Engineer or Party Wall Surveyor. If a building or structure is a risk of movement, then a monitoring survey is usually commissioned.

Typically, monitoring surveys are commissioned when undertaking heavy construction works next to existing buildings. Some examples include:

• Piling works
• Underpinning
• Basement excavation
• Demolition

A monitoring survey scheme can also be commissioned where an insurance claim is being checked.

It is very important that you have at least one survey prior to any works being undertaken. This is to ensure you have a base reading to compare any future readings against. If you start after works have taken place, then you may miss any initial movement in your structure.

During major operations such as digging, underpinning, concrete pours etc then we recommend a survey every week until this is completed.

Once the intense, heavy works have been completed then this can be reduced to say a monthly visit until the internal fit out works begin. Once the internal fit out (plastering / painting / decorating) has begun, then any movement will likely be limited, so the monitoring can cease.

We recommend speaking to your project manager or party wall surveyor about monitoring intervals. Some projects require more frequent intervals, whilst some specify less!

Monitoring survey data is usually presented in report and graph format. The reports will outline movement over time. It’s common to see reports showing movement compared to the previous set of readings, as well as the initial set of readings.

Graphs can also be produced to show the movement in a graphical sense. Graphs can help show when movement started occurring.

Movement monitoring surveys are a good way to help prove or disprove that movement within a structure has been undertaken. This can help with future claims, either made for or against.

Diligent contractors ensure that they minimise movement as a result of construction, however claims from neighbours can still arise.

The movement monitoring reports produced can demonstrate movement or lack of overtime. This can be used in counter-claim situations whereby neighbours insist that damage has occurred.

Another purpose of monitoring surveys is from a safety perspective. If a building is moving during construction works, then this can be identified. If a movement exceeds a certain level, then this can be flagged. The potential source of the movement can be found and mitigated against prior to any problems that could potentially endanger.

Saving money when possible whilst undertaking a project is important. Below, we explain how this can be done when commissioning a monitoring survey company.

Reduce the amount of targets/locations

When your Structural Engineer or Party Wall Survey is looking to commission a survey, they usually don’t consider the company who has to undertake the works. Complicated monitoring survey proposals that require multiple total station setup locations add a lot of complexity and time to a job.

Keeping things simple

Simplifying what is required can often make little difference to the effectiveness of a monitoring survey, and can unlock considerable savings if the following elements are considered:

• Can the survey company easily set up with access to their off-site control network?
• Can we reduce the number of monitoring points?
• Are the monitoring points safe and easy to install?

Increase the monitoring interval

Often a surveying company will quote for a monitoring survey job based on a per-visit basis. A simple way of reducing the overall cost of a monitoring survey is to simply reduce the amount of surveys.

• Can a weekly specification be pushed to a 2 weekly interval?
• Can we do fewer surveys whilst less intense work is being undertaken on site?
• Is it possible to pause the survey work whilst the site is temporarily shut down?

Check their experience

The experience of your monitoring survey team has the possibility of significantly increasing your costs. An incompetent survey company can incorrectly report results and show general inconsistencies. It is important you check the following aspects of a survey company prior to appointment.

• Experience in undertaking monitoring surveys
• Level of insurance for the works.
• What is and isn’t included in their price.
• Reviews from others (Google, Trustpilot ETC).

We provide you with accurate data and easy to understand survey reports. We have been engaged on a number of projects ranging from small basements to large earth moving projects.

Our clients receive great service from us, which is reflected in our 5 star reviews on Google and Trustpilot. We ensure you are happy before, during and well after the project has ended.

As a professional surveying company, we carry all the relevant insurance to give our clients confidence in what we produce. We offer a money-back guarantee on all our work and have £5 million in both professional and public liability insurance.

We undertake local topographical land surveys in the counties surrounding our offices. These include:

• London
• Essex
• Kent
• Hertfordshire
• Sussex
• Surrey
• Buckinghamshire

However, we have been much further afield within the UK and internationally. We have undertaken surveying work as far away as Liberia in West Africa.

If you would like a quote for a project, then please get in touch.

Absolutely, we can liaise with your design team directly or even discuss what you may require for your project. We have undertaken 100’s of monitoring survey projects so know what is usually required depending on what you are looking to build.