Saving the Great London Plane of Ely: Engineering support for an ancient tree

Abstract

The Great London Plane of Ely is the largest London plane in the UK and one of the oldest. At over 350 years old and approximately 40 m tall, it is recognised as one of the Top 50 Great British Trees. The tree is in good health, but it has suffered some decay in recent decades and was at risk of losing a major branch, which would most likely have led to the collapse of the tree. This paper describes some unique work to characterise the dynamic behaviour of this ancient tree, as part of a combined effort by engineers and arborists to save it for future generations. Starting from a geometric LiDAR survey, a finite-element model was created using best-estimate material properties from a combination of laboratory and in-situ testing. The model was validated with the help of video-based modal analysis and dynamic measurements from a remote monitoring system, before being used to guide the design of a new cable-bracing system to provide the tree with structural support.