European research action on relations between technical urban infrastructure and vegetation (COST)

Brussels, 29 March 2002

European Cooperation in the field of Scientific and Technical Research - COST - Secretariat.
Memorandum of Understanding for the implementation of a European Concerted Research Action designated as COST Action C15 "Improving relations between technical infrastructure and vegetation." Brussels, March 2002 (document COST 230/02). Full text

Delegations will find attached hereto the text of the abovementioned Memorandum, signed in Brussels on 12 March 2002 by Italy, on 13 March 2002 by Denmark, Gemany and Sweden and on 19 March 2002 by the Netherlands.

The Signatories to this Memorandum of Understanding, declaring their common intention to participate in the concerted Action referred to above and described in the Technical Annex to the Memorandum, have reached the following understanding:

1. The Action will be carried out in accordance with the provisions of the document COST 400/94 "Rules and Procedures for Implementing COST Actions", the contents of which are fully known to the Signatories.

2. The main objective of the Action is to improve methods and technology related to the coexistence of technical infrastructure and vegetation in European cities and to prevent potential problems arising from their interaction, by an interdisciplinary approach.

3. The overall cost of the research activities carried out under the Action has been estimated at Euro 7million in 2001 prices.

4. The Memorandum of Understanding will take effect on being signed by at least five Signatories.

5. The Memorandum of Understanding will remain in force for a period of four years, unless the duration of the Action is modified according to the provisions of Chapter 6 of the document referred to in Point 1 above.

TECHNICAL ANNEX

COST Action C15 "Improving relations between technical infrastructure and vegetation"

A. BACKGROUND

Vegetation plays a vital role in the urban environment. Unfortunately it can also create problems by causing damage to technical infrastructures such as sewage pipes, roads, railways and buildings.

The damage is often the result of the restriction of the vegetation to a small growing niche in the competition for space with technical infrastructures. If such conflicts cannot be identified at an early stage, and every effort made to prevent their occurrence, they can lead to disruption of services, great expense and damage to the environment. Some common examples of conflict situations between vegetation and infrastructure are:

* Tree roots penetrating sewage pipes, causing disruption and reducing pipe lifetime.

* Trees interfering with overhead utility cables.

* Vegetation that through root and shoot growth damages paved areas, impairing their function and shortening their lifetime (including railway embankments).

* Clearing vegetation from roadsides in order to improve the road safety threatens biological diversity

* Excavation and trenching work for pipes, roads and other building works can cause considerable damage to highly valued trees in urban environments.

* Limited soil volume for plant growth.

* Soil compaction resulting in an unfavourable soil structure for root development.

* Chemical weed control also causing damage to preferred plants.

The significance of problems caused by infrastructure disrupted or damaged by vegetation and vegetation threatened by the infrastructure has increased in recent years in Europe, particularly in highly urbanised areas. The main reason for this problem is the lack of contact between the professional bodies responsible for planning and implementing technical and horticultural work. In view of the fact that a green environment has a high value for the citizens of Europe, it is important to find solutions to these problems which cross the boundaries between professions and disciplines.

Economic considerations and a too narrow viewpoint have often directed the development of technology and methods to solve only the acute problem. This kind of solution has often led to further damage to the vegetation and higher long-term costs.

An example of how these problems are handled is shown in the case of the disruption of sewage pipe function by invasive tree roots. The methods developed to deal with this problem have so far been aimed solely at solving the functional aspect of the pipes using technical measures such as root hacking, steaming or high-pressure flushing of the root parts inside the pipes; repair/replacement of pipes.

These methods deal with the symptoms rather than the cause, which means that the control measures applied are not sufficiently long lasting. The costs of conventional methods to deal with problems of root intrusion into sewage pipes in Sweden are estimated at approx. SEK 55 million per year (approximately 6 million EURO) and in Denmark approx. DKK 58 million (approx. 7.5 million EURO). During the past decade, studies concerning costs caused by root intrusion have been carried out at SLU (Swedish University of Agricultural Sciences) and FSL (Danish Forest and Landscape Research Institute).

The reasons for root intrusion and solutions to the problem can often be found outside the pipe. The most common reasons for root intrusion are:

* Trees of species with an unfavourable root development pattern are growing or are planted too close to pipes.

* The soil structure and soil status allows the trees to develop a root system that penetrates the pipes.

* The position of the tree in relation to the pipeline

* Pipe joints are unable to resist root penetration

* Root hacking, steam clearing and high-pressure flushing inside pipes stimulates rather than inhibits root growth.

Technical development has taken place with too little consideration of the biological mechanisms that govern root growth, resulting in considerable expense and disruption to services.

Another example is vegetation control along roads and railways. For many years this has been dominated by the use of chemical herbicides, which has been criticised because of its effects on the environment and on health and safety conditions for workers. Various non-chemical control measures such as weed brushing and thermal control by flaming have been developed and are in use. The problem of weeds on railway embankments and different possibilities of controlling weeds by non-chemical methods has been discussed at international conferences arranged by EWRS (European Weed Research Society) during the 1990s. Prohibition on a national level and local restrictions have resulted in no use of chemicals against weeds in a large number of Swedish towns and cities and by the Swedish National Road Administrator. In 1995, SLU published a review of preventive measures and non-chemical methods for vegetation control on railway embankments that internationally was very well received.

An optimal vegetation control, with respect to economic and environmental considerations from a long-term perspective, requires an approach that is not based solely on methods to control the growth of existing plants. Preventative measures that restrict the spread of plants must also be included. Such measures should be defined at the planning stage; design, plant selection and installation methods must be chosen with the aim of restricting the opportunities for unwanted vegetation to spread, e.g. stolon barriers installed in embankments to prevent weed infestation from surrounding areas. Other opportunities are selective maintenance strategies where species considered acceptable along roadsides, embankments or in aerial line corridors are favoured through selective weeding while unwanted weeds are removed. Thus a more stable plant community can develop, which in the long-term will require less maintenance to prevent conflict with technical infrastructures.

The examples above illustrate that a broad interdisciplinary approach is necessary to resolve conflicts between vegetation and some technical infrastructures (Figure 1).

Figure 1. Improved interdisciplinary communication is needed to prevent and resolve conflicts between vegetation and infrastructure, which means lower costs and an improved environment.

Research on the subject focused on by this COST Action is at a very early stage. There is no traditional home for this type of research, so you will find it at universities and institutes dealing with agriculture, technology, biology/ecology, architecture etc. Examples of subjects are landscape construction, (production technology and the knowledge of living and dead construction materials), soil science, plant ecology, plant physiology, landscape planning and landscape management. This spread of research in different research environments and the lack of natural scientific networks, conferences, and implementation make it impossible to give a total view of relevant research centres in Europe. At SLU (Department of Agricultural Engineering and Department of Landscape Planning) interdisciplinary research is carried on including technology, soil science, dendrology, plant ecology, landscape planning and landscape management. At FSL there is ongoing research on landscape management. Other examples of research environments are the Institute for Materials Research (Forschungszentrum Karlsruhe), Technical University of Dresden, Institute for Forestry and Nature Research, University of Trondheim, Aberdeen University (Dept. of Agriculture and Forestry) and Institute of Bioengineering and Landscape Constructions (Austria)....

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