Topographical Surveys

A topographical survey is a measured plan of a site as it stands today: its levels, boundaries, buildings, trees, drainage and every other fixed feature, drawn accurately enough for an architect or engineer to design from. It’s usually the first piece of information a design team needs, and errors in it tend to surface late, when a building doesn’t sit at the level it was drawn or a drive comes out steeper than planned.

Subvision Surveys has more than 3 decades of surveying experience and carries out topographical surveys for architects, developers, contractors and homeowners. Because we also locate underground utilities, we can record what’s above and below ground on the same visit, something many topographical surveyors don’t offer.

A standard topographical survey records:

• spot levels across the site, with contours at an interval to suit the ground
• buildings, walls, fences, hedges and other boundary features
• trees, with their position, canopy spread and trunk size
• roads, kerbs, footpaths, steps and changes in surface
• manholes and drainage covers, with cover levels and invert levels where they can be lifted
• street furniture, lamp posts, overhead lines and visible utility covers

Most of the detail is picked up with robotic reflectorless total stations, which measure to a point without anyone needing to stand on it. That matters on live sites, roads and roof edges. Open ground and large plots are surveyed with GNSS equipment using RTK correction, which gives centimetre-level positioning and ties the survey to the Ordnance Survey grid and datum. Where your project uses its own site grid, we work to that instead.

Surveys are carried out in accordance with the RICS specification for surveys of land, buildings and utility services.

Most sites are surveyed with a total station and GNSS. Some need something else as well:

• Large or rural sites: GNSS surveys cover open ground quickly with centimetre-level accuracy.
• Big, steep or hard-to-reach areas: drone surveys and LiDAR surveys capture ground levels without walking every metre, and LiDAR can see the ground beneath vegetation.
• Building facades and complex structures: 3D laser scanning records millions of points, which can be turned into elevations or a 3D model.
• Inside buildings: a measured building survey produces floor plans, sections and elevations, and can be combined with the topographical survey of the plot.

Every topographical survey is drawn up in AutoCAD and issued as a DWG with a PDF copy. Depending on what you need, that can be a 2D plan with levels and contours, a 3D model of the ground and buildings, or data ready for BIM software. Layers and symbols are set up so your design team can work straight on top of the drawing rather than redrawing it.

If you need the survey turned into planning drawings or developed further, our CAD drawing services can take it on from there.

London sites bring their own problems. Plots are tight and often bounded by other people’s buildings, so the survey usually needs to record neighbouring properties as well: their eaves and ridge heights, window positions and the levels at the boundary. Architects need that information for daylight and sunlight studies, rights of light and basement schemes, all of which come up far more often in places like South Kensington, Notting Hill or Fitzrovia than on a greenfield site.

Tall buildings and narrow streets also block satellite signals, so GNSS can’t be relied on in much of central London. There we run a total station traverse to carry accurate control through the site and tie it back to the Ordnance Survey grid. Work on the public highway, whether that’s a shopfront in Covent Garden or a terrace in Shoreditch, is planned around traffic, parking and pedestrians so the survey can be done safely and in one visit wherever possible.

Trees are another London issue. Many sites sit in conservation areas or have trees protected by a Tree Preservation Order, and an accurate tree position and canopy spread on the topographical survey is often the starting point for the arboricultural report a planning application needs.

A topographical survey shows manhole covers but not the pipes and cables between them. On most development sites the design team also needs to know where the buried services run, and that usually means a separate contractor and a second drawing that has to be lined up with the first.

We can carry out underground utility mapping or a PAS128 survey alongside the topographical survey, with both recorded on the same control and issued on one drawing. Drainage can be added with a CCTV survey to confirm pipe runs, sizes and condition between chambers.

We’re Essex-based, working nationwide, with a team of over 25 surveying professionals. There’s more detail on local ground conditions and the areas we cover on our pages for topographical surveys in Essex and topographical surveys in Kent.

All of our surveyors are DBS checked and hold valid CSCS cards, and the business is SSIP and ISO accredited.

Call us on 0333 920 9427 or use the form. To give you an accurate quote, it helps to have the site address, a red-line plan or rough boundary, what the survey is for (planning, design, boundary or setting out), and whether you need neighbouring buildings, roof heights or underground services recorded as well.