●A Case of Utilizing Results

Manual of the countermeasures for tree failure of streettrees
MATSUE Masahiko, HeadIIZUKA Yasuo, Senior Researcher
Environment Department, Landscape and Ecology Division(Key words) Street trees, lodging, degree of danger, diagnosis, maintenance
1. Introduction
Street trees, which can be lodged by typhoons orother strong winds, may block traffic or obstructpedestrians and in the past, have caused accidents
including personal injuries.
The Manual proposes diagnostic methods to clarify
structural tree trunk infirmities and treatment measures
to reduce danger in order to minimize the danger
posed by lodging of street trees.

necessary to eliminate or mitigate danger from trees
shown by a soundness inspection to be extremely
dangerous, considering their functions as street trees.

2. Outline of the Manual on Lodging
Countermeasures for Street trees
Lodging countermeasures for street trees areimplemented by the following procedure (Fig. 1).

3. Public announcement of results
The achievements have been announced inTechnical Note of the National Institute for Land andInfrastructure Management, No. 669.
The Manual is counted on to maintain healthy street
trees to contribute to the conservation of abundant
green living environments.
http://www.nilim.go.jp/lab/ddg/(Landscape andEcology Division)(5) Lodging verification inspection
When a street tree has caused an obstruction bylodging etc., after determining the cause of the lodging,
the suitability of tree soundness inspection orimprovement measures is verified.

(1) Preliminary diagnosis
The preliminary diagnosis is done to easily visuallyclarify any problems with the shape or vitality of trees,
tree trunk infirmities, etc. in order to identify
dangerous trees which require tree soundness
inspections or planting environment inspections fromamong the many trees along roadsides.
(2) Tree soundness inspections
Tree soundness inspections are
performed to clarify: [1] defective rootsystem elongation resulting from poor
growth of trees, [2] and the decline of
supporting strength caused by structuralinfirmities such as hollows or decay
caused by wood-rotting fungi intrudingfrom breaks in the bark on the tree trunk,
which are the major causes of lodging
during typhoons or other strong winds.
(3) Planting environment inspections
Plantingenvironment
inspections
include inspections of growing conditions
performed to clarify the planting ground,weather conditions, and state of support
poles or other supporting materials, andobstruction inspections which predict
obstructions which will be caused when astreet tree has actually lodged.
(4) Improvement measures
Improvement measures are measures

Preliminary diagnosis
By a simple diagnosis, clarify problems with the shapes or vitality of trees, tree trunk
infirmities, etc., identifying roadside trees which require tree soundness inspections orplanting environment inspections based on the results.
Abnormality orinfirmities found

Tree soundness inspection
Growing state inspection
Evaluation of state of growth of tree bytree shape inspection and vitality
inspection
Danger inspection
Tree trunks are inspected visually forsigns of structural infirmities, and if amore detailed diagnosis is required,decay is measured and root systemelongation is inspected to evaluate
danger of lodging.

Abnormality orinfirmities not
found

Tree shape or vitality problems
Infirmity of tree trunk requiring emergency
measures

Planting environment inspection
Growing condition inspection
Evaluation by inspecting topography or weather
conditions at planting location, state of support
poles and other protective materials.

Obstruction inspection
Categorizing land use of planting locationand shape of planting groundaccompanied by prediction of objects
obstructed and size of obstruction
caused by lodging and breakage ofbranches.
Infirmities of tree trunks requiring emergency
measures

Daily management
Pruning or otherregular management
tasks
Improvement measures(emergency)

In the case where apreliminary diagnosis
has confirmed a
problem with theshape of a tree or its
vitality, improvement
measures are taken.
Case where apreliminary diagnosis
or tree soundness
inspection etc. hasconfirmed a defect of
the tree trunk
requiring emergency
measures,emergency measures
are studied andperformed.

Improvement measures
In response to results of evaluations of inspections, the best measures are studied and rapidly taken according to the degreeof danger.

When a tree lodges.
Lodging verification inspection
When a tree has lodged or a branch has broken during a typhoon or strong wind, clarifying the cause of the lodging and at thesame time, comparing the findings with diagnosis results to verify the cause to improve future diagnosis technologies.

Figure 1. Street Tree Lodging Countermeasure Flow Chart