City Of Monona Tree Failure Study

  • In May 2005, unusual wind direction and higher-than-normal wind velocity caused a 30-inch diameter honey locust to lean over a busy road in Monona, Wisconsin.
  • The tree fell unexpectedly during rush hour traffic, crushing a car and killing the driver.
  • The city of Monona contracted with Allison to determine the cause of the tree failure.
  • This incident was an uprooting. It exemplifies the importance of an in-tact root plate in order to maintain tree stability.
  • Allison arranged to have the entire stump excavated.
  • Removing the soil w/ a fire hose allowed Allison to carefully examine the condition of the root plate and make measurements to determine where the area of decay and root rot had started.
  • In this particular case the area of decay was below the root line and would not have been observable to any passers-by or observation from the road.