At present, the most accepted method for evaluating the safety and stability of tree roots
Applying a bending load on the trunk via a cable attached to the tree
Assess the uprooting stability of the tree
Or to establish the risk of trunk breakage.
Remark: there are overlaps among the equipments needed for DynaRoot and Pulling test. If you order both of them at the same time you can ask for a switchable Dual Elastometer Unit and High Precision Inclination and Deformation Recorders.
Make sure you follow all the safety instructions throughout the test!