BS5837 Map

This program is written specifically for users who are familiar with the concepts relating to BS5837:2005, "Trees in relation to construction". It is designed to assist Arborists to map three key aspects of this British Standard.

The two trees in this example are partially enclosed by walls. Their Root Protection Areas are shown in red and their crowns in blue and green - these being the colours specified in the British Standard for trees of categories A and B. The shape of the crowns has been determined by the crown dimensions along the cardinal directions. The shadows are calculated for 10 am on the spring equinox at latitude 53 degrees North.

1. The shape of the crown. BS5837 requires that the crown of the tree be measured from the trunk in four directions: north, east, south and west. This program accommodates these four measurements within an appropriately distorted circle.

2. The Root Protection Area. The British Standard provides a calculation method to determine the Root Protection Area (RPA) in square metres for a given stem diameter in mms (measured 1.5m above the ground). The area is assigned a different value if the tree has multiple stems, that is, if the branches start below 1.5m above ground. In this case the stem diameter is replaced by the "basal diameter" which is measured immediately above the root flare. This program calculates the RPA for both single and multiple stemmed trees.

In an open field, the Root Protection Area (RPA) is a simple circle. Where there are physical barriers to root growth, such as a wall, the shape of the RPA must be curtailed at the barrier and extended elsewhere. This program will create a modified RPA to take account of barriers.

3. Overshadowing. BS5837 makes no calculable recommendations regarding overshadowing but it does emphasize that overshadowing should be considered. This program models the extent of shadows for any user specified month and time of day at any location in the UK.