Intersect Site Surveying. Intersectional Surveys.
What Is an Intersect in Surveying? – Cadmap Ltd
An intersect survey (intersection method) is a surveying technique used to accurately determine the position of an unknown point by observing it from two or more known locations. Instead of measuring directly to the point, surveyors take bearings, angles, or distances from multiple instrument setups and compute where those sight-lines or distance arcs meet. The crossing location is the calculated coordinate of the point.
At Cadmap Ltd, we use intersect methods regularly in both topographical surveys and measured building surveys, especially when a feature is:
Inaccessible (behind fencing, watercourses, railway lines, or private land)
Unsafe to reach (roof edges, parapets, cliff faces, structures at height)
Obstructed by vegetation or hoarding
Too fragile or protected to approach directly
Why Intersects Matter
Intersects allow us to obtain precise coordinates where traditional measurement is impossible. They protect sensitive structures, improve detail capture, and maintain high accuracy across the entire survey dataset.
Types of Intersects
Angular intersection – Using bearings or horizontal angles from two known stations.
Distance intersection (trilateration) – Using distances from multiple known points.
Combined methods – Mixing angles and distances for higher redundancy and accuracy.
Applications at Cadmap
Cadmap surveyors often use intersects for:
Building corners hidden behind scaffolding
Ridge heights, parapet edges, chimney stacks
Tree canopy centres and crown spreads
Watercourse features or hard-to-reach boundaries
Remote or ecologically restricted areas
Accuracy & Best Practice
Wide, stable baseline geometry
Redundant observations from additional stations
Calibrated instruments and orientation checks
GNSS control integration where appropriate
Cadmap Expertise
With advanced total stations, GNSS, and specialist survey software, Cadmap Ltd delivers reliable intersection calculations as part of fully connected RICS-compliant surveys. Whether for planning, design, boundaries, or construction, our team ensures that inaccessible features are captured with full accuracy and clarity.
