The Planning Application That Turns on a Category Grade
A developer submits a planning application for a residential site with twelve trees. The local planning authority requires a BS5837 tree survey. The surveyor walks the site and assigns each tree a category: A, B, U, or R. Category A trees have an estimated remaining contribution of forty-plus years — they are high-value assets and their retention is a material planning consideration. Category R trees are in the final decade of useful life and can typically be removed without objection.
The developer's architect is designing around which trees stay. The planning officer is checking whether the protected A-category trees are being preserved. The landscape contractor is waiting on the work schedule derived from the survey's Work Grading column. Everyone is working from the same BS5837 survey output, and the data that drives every decision is in this template.
DBH Calculation: The Formula That Saves the Stopwatch
Diameter at Breast Height (DBH) is the standard trunk measurement in arboricultural surveying, measured at 1.3 metres above ground level. In practice, it's far easier to measure circumference at breast height (CBH) with a tape than to measure diameter directly on a standing tree. The conversion is CBH divided by π.
DBH Calculation = #{cbh}/3.1415
Enter the CBH in the field, and the DBH calculates automatically. A CBH of 125cm returns a DBH of 39.8cm. No mental arithmetic, no rounding error on the datasheet, no inconsistency between what the tape measure shows and what the report states.
Crown Spread in Four Directions: The Structural Footprint
CS NORTH, CS EAST, CS SOUTH, CS WEST — four measurements from the trunk centre to the outermost branch tip in each compass direction. Together they define the crown footprint, which determines the Root Protection Area (RPA) used for site planning, construction exclusion zones, and underground service routing.
An oak with CS values of 8m/7m/9m/6m has an asymmetric crown that extends differently in each direction. The planning exclusion zone is not a simple circle — it follows the actual crown geometry. Without the four-direction measurement, the RPA calculation uses an average that either over-protects (and loses usable site area) or under-protects (and puts the root system at risk from ground disturbance).
Height of Ground Clearance records the clearance beneath the lowest branches — critical for determining whether the tree presents a pedestrian or vehicle obstruction risk and whether crown-raising work needs to be specified.
Category Grading and the Retention Decision
Category A (40+ years remaining contribution): significant landscape or amenity trees. Category B (20-40 years): moderate-value trees with meaningful retention prospects. Category U (10-20 years): low-value trees in the final phase of useful life. Category R (under 10 years): trees being retained only for specific short-term reasons, typically removed without objection in planning contexts.
Estimated Remaining Contribution in years is the surveyor's professional estimate that determines which category the tree falls into. A Mature oak in Good physiological condition and sound structural condition might be assigned 60 years. A Semi-Mature Ash with Poor physiological condition showing dieback and Ash Dieback infection might be 8 years — Category R.
Work Grading on a 1-2-3 scale prioritizes the recommended work queue: Grade 1 is urgent safety work, Grade 2 is routine maintenance within 12 months, Grade 3 is desirable longer-term management work. The survey doesn't just describe the trees — it schedules the arborist's workload.
Type captures whether the record is a single Tree (T), a Group (G), an Area of trees (A), a Shrub (S), or a Hedge (H). A group record can cover twelve semi-mature birches that would take twelve individual entries — assigned a single group category, a single set of work recommendations, and a shared GPS location pin.