Trees growing almost against the road kerbing are always a concern, since we know that they will have massive injuries to 50% and more of their structural roots, it is almost certain that at some point down the track these trees will be colonised by fungi.
In Ekka's pics you can see clearly where the replacement kerbing set back was, how all the roots were severed, torn and fractured providing ideal infection courts for any latent spores that might be present. You can also see where the fruiting bodies suggest advancing decay in structural roots on the other sides of the stem....very serious indeed
Roots growing very near or non the soil surface as many do, have a classic form to them radial growth is restricted in the soil itself and the physical action of supporting the tree resisting wind loading forces leads to this form. Here's a very simplified diagram
When a root rot fungi colonises and consumes the wood tissues (allowing for the different preferences in fungi for cellulose, lignin etc...simplified again) the decay tends to follow the same pattern leaving behind what appears on the surface to be solid timber, but is not.
This can be very simply and quickly detected by the use of a nylon or wooden mallet...sounding the roots, the tell tale hollow ring is unmistakable.
