Many people have died, and many more are badly injured, but the tradition survives. It has been around for more then 1200 years, and is due occur again in 2016.
The log riding is one of several parts of a ceremony of renewing the shrine.
Stages of this tradition are as follows:
Caring for and grooming the tree
Creating the tools for cutting down the tree
Cutting down the tree
Bringing the tree across the rough terrain back to the shrine (and hence the log riding)
Raising the tree/pillar by hand