Vegetation Control on Railway Tracks and Grounds
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Vegetation
Control on
Railway
Tracks and
Grounds
Swiss Agency for
the Environment,
Forests and Land-
scape (SAEFL)
BUNDESAMT FÜR VERKEHR
OFFICE FÉDÉRAL DES TRANSPORTS
UFFICIO FEDERALE DEI TRASPORTI
FEDERAL OFFICE OF TRANSPORT
Imprint Contents Strategy, Solutions and Limitations 3
Publisher Things We Should Know About Plants... 4
Swiss Federal Railways (SBB/CFF/FFS),
Swiss Agency for the Environment, Requirements of the Different Track Areas 6
Forests and Landscape (SAEFL),
Federal Transport Office (BAV) Weighing of Interests 8
This brochure is based on the report Environmentally Favourable Vegetation Control 10
entitled «Ausgewählte Verfahren zur
Vegetationskotrolle auf Bahnanlagen» , Prevention of Undesired Vegetation 11
by Christian Müller, Swiss Agency for
the Environment, Forests and Landscape, Constructional Measures 12
1999, in No. 108 of its publication
«Umwelt-Materialien» . Biological Measures 14
Editorial team Mechanical Measures 16
Christian Müller, Grossaffoltern;
Helmut Kuppelwieser, SBB; Chemical Measures 18
Roland von Arx, SAEFL;
Rolf Beyeler, Olten Thermal Measures 20
Associated Working Party Selection Criteria 21
Federal Transport Office (BAV),
Swiss Federal Railways (SBB), Comparison of Different Measures 22
Public Transport Union (VöV),
Swiss Federal Research Station for Fruit- Common Weeds in the Track Area 24
Growing, Viticulture and Horticulture,
Wädenswil (FAW), Possibilities and Limits of Vegetation Control 26
Swiss Agency for the Environment, Forests
and Landscape (SAEFL) Annex: Bibliography, Glossary 30-32
Swiss Federal Roads Office (FEDRO),
Swiss Federal Office for Public Health Basic and further education possibilities, Information 33
(SFOPH)
Design and layout
Textext Olten
Translated from German by
Hans Bamert
Photographs
Christian Müller, SBB Documentation
Service, Helmut Kuppelwieser,
Jean-Pierre Mettraux, Barbara Bott
Source of supply
German and French versions of this SBB AG, Bern
document are available from the same Rail Environmental Center
address. Parkterrasse 14
CH-3000 Bern 65, Switzerland
© BAV/SAEFL/SBB 2001 Tel +41 512 20 58 19
Fax +41 512 20 44 75
4.2001 800 52446 E-Mail umwelt@sbb.ch
1
Strategy, The main concern today is to bring Target Group
vegetation under control through the
use of a combination of different
Solutions and measures appropriate to the specific
To optimise vegetation control from an
economical and ecological point of view,
situation. More specifically, this it is essential for all the technical
Limitations means that preventive measures departments of a railway company to be
should already be addressed in the aware of the problems associated with
planning and projecting phase, and railway vegetation and to have some
Modern train operation makes very high that the periodical maintenance of basic knowledge of the subject. If, for
demands on railway tracks. These the lines must be guaranteed. To example, the question of vegetation
demands can only be met if the ballast complement this, existing vegetation control is already taken into account
bed is as much as possible free of is removed using measures that during the planning and projecting phase
vegetation. In earlier years, soil herbicides combat the symptoms. of a new line construction or renewal
were used to achieve this goal. However, scheme, this will help to reduce the time
the chemicals used (such as Atrazine) had This brochure is designed as a basic guide and money spent later by the mainte-
a low degradability. This and the high for anyone involved in vegetation control nance services. This brochure is therefore
permeability of the track sub-structure led on railway tracks and grounds. Its directed to all those responsible for
to pollution of ground- and drinking purpose is to make people aware of the
water. A working party comprising possible options and problems whilst also ➠ planning
Overgrowing vegetation in the representatives from SBB, private describing the current methods and how
track area can be a danger to railways, agricultural research centres, the they can be combined. ➠ project work
railway operation. Weeds must be Federal Transport Office (BAV), the Swiss
controlled with measures Federal Office for Public Health (SFOPH) ➠ execution
appropriate to the location, and the Swiss Agency for the
and to the type and Environment, Forests and Landscape ➠ maintenance
extent of line use. (SAEFL) was set up to take a new look at
vegetation control on railway tracks and ➠ renewal
grounds.
➠ regeneration
The working party, chaired by SBB,
investigated other methods of vegetation associated with railway installations, or to
control in an effort to find alternatives to those involved in the related activities.
chemicals. Particular attention was given
to constructional, biological, mechanical
and thermal measures.
Just how free of weeds the track
area must be will depend above
all on the operational
requirements the line must meet.
The control measures described in
this brochure are designed to
guarantee productive efficiency
and operating safety of the
railway in the long term, whilst
ensuring the best possible
protection for the environment.
2 3
Things We Basic principles Seed dispersion Species propagating Species propagating
of plant growth species above ground from below ground
Should Know To grow, plants need light, nutrients, and The installation of coarse-grained Most plants propagate and spread Problem plants like brambles or traveller’s Plants that penetrate the track area
above all, water. The less water there is separating layers without humus, silt through seed dispersion. These types can joy propagate by sending out runners underground, such as horsetail or reeds,
About Plants... available to a plant, the less it grows. and clay has an extremely stunting efficiently be controlled through above the surface. Where a runner comes are the hardest to control. These species
effect on the settlement and growth constructional measures designed to into contact with the soil, new roots start by pushing their roots horizontally
To survive periods of little precipitation, of most types of plants. inhibit growth. form, from which runners are again sent out into the damp natural subsoil before
A basic knowledge of plant growth is plants depend on the water-holding out. If however the runners are forming new shoots at the surface, which
a prerequisite for effective vegeta- capacity of the soil, which on its part is a In principle, three main groups of plant Seeds normally germinate at the surface continually cut back, the plants are then grow into new plants that send out
tion control. This can lead to a better function of the soil structure. Humus, fine- species are of importance in track-bed of the soil and their roots then grow unable to propagate further. their own suckers. Their roots or shoots
understanding of the interactions grained silt and clay can hold large maintenance. These are described in more down in search of water. If the roots can can even penetrate heaps of dry gravel,
between the measures taken and quantities of water, whilst coarse-grained detail below. locate neither water nor nutrients – in Plants that propagate in the track drainage concrete or scree material.
plant behaviour. It can also help materials like washed sand, stone other words if the ballast bed and verge area by sending out runners above
avoid inappropriate applications that chippings, ballast and boulders do not are free of dirt able to store water and ground can be kept under control by In this way, a whole network of roots
are not effective, or whose effect is have this ability. They repress plant nutrients – the young plants will simply regular cutting back and mowing in develops. This root system can be
even counter-productive. Reference is growth. A thin separating layer of coarse- die. the bank area (see «Mowing» p. 15). between 1 and 2 metres below the
also made in this connection to the grained material is usually sufficient to surface, with extensive, interlinked
overview of common problem plants cut off the roots from the water supply. For this reason, new verges should be ramifications spread over a considerable
on pages 24 and 25. built up with a coarse-grained layer area, helping the plants to obtain water
Humus also contains many nutrients that (e.g. gravel, ballast), and in the ideal and nutrients, even in dry periods. These
plants also need in order to grow. case should be covered with fine- species are most common in damp, clay
grained materials such as stone or silty soils.
chippings, and should be periodically
maintained (cf. SBB Regulations In the long term, plants propagating
211.1). For older verges, a periodical from below ground can only be
maintenance is recommended. controlled through renewal of the
substructure.
A typical seed-dispersion plant is Bramble is a typical plant that Reed – a typical problem plant,
cranesbill. propagates above ground. propagating from below ground.
Plants are excellent indicators of
the state of the soil. The rich
growth of horsetail in the picture
shows that the ground in this
area is damp and therefore
unstable. Here, the result has
been track subsidence.
4 5
Requirements Maintenance zones
of the The trackbed construction can be divided Within the zone of intensive mainte-
into the ballast bed, the verge and the nance, safety is the paramount consider-
Different bank. Each of these areas has a different ation. While no growth is permitted in the
Zone of intensive Zone of extensive
role to play and therefore has specific actual track area (the ballast bed), regular
maintenance maintenance
Track Areas requirements on vegetation control. This mowing of the area between the verge
information is set out in detail in the and the bank should ensure that a thick
Swiss standard «SN 671 560». band of grass forms there to prevent
Before combating plant growth in weeds from propagating into the track approx. 5 m approx. 10 m
and around the track area, two basic Beside a differentiation according to area. (from track centre)
questions must be answered: construction elements, to differen-
tiate between intensive and exten- Within the zone of extensive mainte-
➠ Where should or must the track be sive maintenance zones is also impor- nance, ecological and economical aspects
free of vegetation? tant. Special attention must be given have to be considered, besides those of
to the 1 to 2 m wide transition band safety. This can be achieved by regular
➠ Where is a certain amount of between verge and bank, situated in maintenance. In particular, the use of
vegetation to be tolerated, given the zone of intensive maintenance. herbicides is forbidden here.
the age, constructional condition,
traffic density and time to next
renewal of the installations?
To be able to answer these questions,
it is necessary to know the impor-
tance of the different track areas.
absolute limit for trees and shrubs
5˚
.4
ox
pr
ap
Zone of intensive maintenance Zone of extensive maintenance
Track area Transistion band Bank
Maintenance goals ✓ ballast bed stability ✓ stability of bank and vegetation
✓ durability of materials and verge ✓ protection from projecting
✓ unhindered access or falling wood
✓ unobstructed view ✓ protection from the forces of nature
✓ unobstructed view
✓ vegetation barrier ✓ vegetation barrier
Vegetation ✓ none ✓ thick grass ✓ various vegetation types
✓ no shrubs or trees
Measures prevention and promotion and care of
removal of vegetation: non propagating plants:
✓ constructional measures ✓ biological measures ✓ Keeping the clearance gauge free
ballast bed verge 1-2m
✓ chemical measures ✓ Maintenace based on ecological principles
✓ thermal measures including aesthetic considerations
✓ mechanical measures transi-
track area tion bank
Factors to consider ✓ Prevention of water pollution ✓ Preservation of nature and the landscape
band
✓ Cost-effectiveness ✓ Cost-effectiveness
6 7
Weighing of Ballast bed Verges Transition band Banks
Interests With the high speeds and loads of
modern rail traffic, operating safety dic-
The verge can fulfill several functions in
vegetation control depending on the
Regular mowing of the transition band
promotes a dense grassy vegetation. This
Professional maintenance of the railway
banks protects the track area against
tates that the ballast bed be virtually situation. It can serve: is a good barrier against problem plants lateral plant incursions.
When maintaining railway installa-
clear of plant growth. growing into the track area from the
tions or carrying out vegetation con-
➠ as an element in the drainage of the bank. For reasons of operating safety and
trol, a number of different aspects
➠ A dirty or overgrown ballast bed loses track; vegetation control, no trees or shrubs are
must be considered. Apart from pur-
the resiliency that is essential for high ➠ as a barrier to stop plant incursion allowed to grow in the vicinity of the
suing the goals of a long-term safety
operating speeds. reaching the ballast bed; track (about 5 metres from the track
guarantee, also functional efficiency
➠ as a walkway for inspections and centre). Potential hazards include falling
and cost-effectiveness of railway
➠ Plant roots and dirt store water that maintenance work. trees, lack of visibility, excess shadow,
installations, the protection of the
can freeze and expand in winter. This falling leaves and the added humus that
environment, the preservation of the
leads to a change in track geometry Good quality verges are also important such growth would bring.
countryside, and the prevention of
which in the worst case can lead to for work to be performed in the ballast
water pollution, have at any rate to
derailments. area. In Switzerland this protection is ensured
be taken into consideration. The
through regular attention to the banks in
essential obligations to be observed
➠ Plants that grow over the rails can When used as a walkway, it is sufficient accordance with Swiss standard «SN 671
are set down in the environment pro-
reduce adhesion essential to power to keep the verge free of plants like 560».
tection law, the law on the protection
transmission and braking. brambles, traveller’s joy and shrubbery
of regional values and traditions, the
that might make people stumble over
landscape preservation law, as well
them. More vegetation can be tolerated
as the water protection law.
on open lines than in marshalling yards
and stations where walkways are used
Basically, more vegetation can be toler-
every day.
ated on sidings or lightly used connecting
lines. Neglecting maintenance on lightly
used secondary lines will however lead to
a rapid deterioration in their condition,
with the result that speed restrictions
have to be imposed. The lines may even Verges built according to
have to be closed. accepted standards, and in
The extent to which ballast must combination with a grass-covered Regular mowing of the bank
The distinction between zones of inten- be free of vegetation depends and regularly mown transition keeps trees and shrubs at bay and
sive and extensive maintenance gives a above all on the number of trains band can be an ideal vegetation prevents weeds from propagating
clear indication of where the vegetation and their speeds. barrier against weed incursions. into the track area.
must be controlled on railway tracks and
grounds and with what kind of measures.
These requirements can be applied by
analogy to those areas that are visible to
the eye – the ballast bed, verge and
bank. Depending on the characteristics of
the landscape and the age of a line, the
individual areas can vary considerably in
size and condition. The width of the tran-
sition band between intensive and exten-
sive maintenance zones (i.e. between the
verge and the bank) is particularly vari-
able, but should be around 2 metres
wherever possible.
8 9
Environmental- In the longer term however, these effects
Sustainable, environmentally Prevention of ‘Problem plants’ ‘Problem plants’
will decrease, which is why it is so
favourable vegetation control on
present absent
important to maintain the lines (mowing
ly Favourable of the bank in the track vicinity, cleaning
railway tracks and grounds is Undesired The best way to deprive problem plants Seed plants, and plants propagating
possible if the following priorities
out of drains). Even though vegetation (e.g. those that propagate from under- above ground can best be combated by
Vegetation control is not the primary objective of
are observed:
➠ prevention of plant growth
Vegetation ground) of water they need for survival, is plant- inhibiting construction measures
some maintenance works such as ballast to build deep-set drainage systems, and (substructure materials without clay, silt
through appropriate con-
Control cleaning, these often have a salutary and
structional and biological at the same time to replace the whole or humus). A sufficiently thick (confor-
wished-for side effect. Plant incursion into the track area layer of soil interspersed with roots. But ming to SBB Regulation R 211.1) and
measures;
can best be prevented or discouraged mostly, this procedure is possible only in clean ballast bed will be especially effec-
Where vegetation persists in the track
➠ preservation of the growth- by ensuring that conditions of growth
The methods of vegetation control connection with a renovation of the tive in durably depriving seed plants of
inhibiting state through
currently used by SBB can be divided area in spite of constructional measures in the verge are as unfavourable as substructure, and it is the most cost- their necessary basis of existence. After
regular maintenance;
into two main groups: procedures for and regular maintenance, plants can be possible (reducing the amount of effective if the verge is to be renovated rainfall or other forms of precipitation, it
removed mechanically, chemically or
➠ removal of vegetation by water, nutrients and light). However,
removing or repressing existing vege- for operational reasons. is important for the ballast to dry out as
mechanical, chemical and
tation, and measures directed to the thermally, depending on what is the success of a given method will fast as possible – the track should there-
thermal means as and when
causes of plant growth. In practice, it permitted. depend on the type of vegetation A cheaper method is to insert foils into fore not be overshadowed by trees. The
necessary.
is usually an optimal combination of and the site in question. To combat the verge. These foils should be resistant lateral drainage of the substructure and
a variety of measures that is the most some so-called problem plants (see to root growth, degradation and weather the ballast bed also has to be
effective. p. 24 and p. 25), other methods than influences (see page 13). A precondition guaranteed.
those used for normal weeds are for this is that water run-off is provided
In principle, constructional and biological required. and that sufficiently strong competition Plants usually start to grow at the base of
measures are the most effective when a vegetation is stimulated in the adjoining the ballast shoulder, where the ballast
line is built or renewed (bituminous weed transition band. This helps to limit lateral layer is the thinnest. Ensuring that a suffi-
barriers, porous concrete barriers, lateral incursions by problem plants (compare ciently thick layer of ballast reaches as far
barriers and green bands with selected «Mowing», p. 15). as the verge can therefore also help
vegetation). These measures prevent The methods of vegetation prevent plant growth.
plant growth by reducing the amount of control used by SBB today. In
water in the substructure and serving as practice only an optimum Well placed and solid cable trenches,
a barrier against plant incursion. combination of measures will The absence of shade trees tends concrete border elements, covered porous
generally deliver a sustainable to discourage plant growth in the concrete barriers and solidly-built verges
and cost-effective result. track area. are suitable as lateral barriers against
plant incursion into the track area.
Prevention Removal and repression As experience shows, a substructure
of undesired vegetation of undesired vegetation made of sand and gravel without a bitu-
(combating the causes) (combating the symptoms) minous layer does not meet the require-
ments of a plant-inhibiting construction
design. The sand and gravel mix alone
cannot ensure complete dryness.
constructionally biologically mechanically chemically thermally
see page 12 see page 14 see page 16 see page 18 see page 20
Combination of methods tailored to the situation in hand
Environmentally favourable vegetation control
10 11
Constructional Bituminous weed Verge design Lateral barriers Porous concrete Insertion of foils
barriers barriers
Measures A sufficiently robust and compact layer of Verges with a compacted, wear-resistant Verges that are built with a plant inhibi- The porous concrete barriers that SBB has Integrating foils in the construction of the
bitumen beneath the ballast is a solid top layer of a finer material will inhibit ting construction, already constitute ef- built in the verges of existing lines since verge is a simple way of preventing plant
barrier against rising soil moisture and most forms of plant growth. A smooth fective barriers against plant incursion. the late 1980s are a good barrier against incursion. These foils must however be
Constructional measures designed to
also prevents pollution and softening of verge surface that slopes towards the With the addition of cable trenches, bars plant incursion. They can be built quickly undegradable, resistant to atmospheric
reduce the amount of available water
the substructure due to precipitation outside has the additional advantage that and step blocks as lateral barriers, the and easily and at reasonable cost, and corrosion, and must resist root growth of
in the track area have proven to have
soaking into the ground. almost no organic matter can settle on it. overall effect is even enhanced. Where are therefore particularly suited when ex- horsetail and reeds (e.g. fleece is not
the best preventive effect against
With time, though, some unpretentious verges are lacking or need to be raised, isting lines are reconstructed. Concrete suitable, as plants can grow through it).
weeds. However, because of the high
Bituminous weed barriers that conform to plants will grow here. To keep the verge concrete slabs in upright position are also barriers for drainage must however not If, however, problem plants are already
costs involved in the construction
Swiss standard «SN 640 431b» stop the free of vegetation for a longer time, suitable. However, a proper drainage of impede the mowing of the adjacent band present, then also the foils will not be
work and the disruption of opera-
propagation of problem plants from extremely growth-inhibiting materials can the track structure must always be of grass. able to stop them.
tions, measures of this type are not
below almost entirely. be used for the verge (gravel made of ensured. When the foils are built in, attention
cost-effective if their sole purpose is
calcium-free silicate). Bear in mind that Requirements governing the installation should be paid to ensuring that water
vegetation control. It is therefore
Cost: 20 - 80 sfr./metre this measure on its own will not deter Cost: 300 - 800 sfr./metre of porous concrete barriers are set out in run-off from the sides of the ballast bed
necessary always to take due account
plants that propagate from beneath the Annex 9 to SBB Regulation R 211.1. Cov- is guaranteed and that the foil reaches
of vegetation control aspects when
surface. ering the concrete barriers with a layer of around 50 cm under the ballast. It must
engineering works are planned for
finer material can help to efficiently filter slope sufficiently outwards, which means
operational reasons. The basic
If the verge and transition band are given out humus and nutrients. that the verge surface must previously be
requirements for constructional
regular care, verges built in this way in renovated. The foil must also be secured
measures are set out in SBB Regu-
areas that are largely free of problem Cost: 150 - 300 sfr./metre against the wind using gravel or a similar
lation R 211.1.
plants (e.g. reed and horsetail) should last material.
for anything up to 30 years (except for The costs indicated below result from a
very steep banks without shoulders and trial scheme and are therefore rather
narrow cuttings). high. Were the foils to be laid concur-
rently with rebuilding work, substantial
Providing the underlying drainage layer savings would result.
and barrier have a proper effect, a
replacement of the overgrown, humus- Cost: 100 to 150 sfr./metre
rich layer of gravel on existing verges,
provides for a new growth-inhibiting
Bituminous weed barriers today
effect for several years against wild seed
are standard procedure for SBB, Properly built and maintained This gap in a porous concrete
plants. The new surface material, selected
among other constructional verges can repress undesired Solid cable trenches form good barrier illustrates the Where the foil ends, the
for its grain size properties, will
measures. vegetation for up to 30 years. barriers to the incursion of plants. effectiveness of this technique. vegetation spreads.
nonetheless need to be compacted.
Verges built on new lines are now
composed of ballast because of its better
permeability. Since in this case vegetation
can only be removed at substantial cost,
the verge must be kept free of plant
growth by regular and professional
maintenance (see «Biological Measures»,
p. 14).
Cost: 20 - 30 sfr./metre
12 13
Biological fact that at specific places, the replace- Greening Mowing Selective
ment of unsuitable, loamy soil has always maintenance
been a tried method of the railways to
Measures improve track stability. The deliberate sowing of desired plants Without regular attention, vegetation will Motor scythe Outside the area of intensive mainte-
will generally follow after completion of develop into woodland in most cases. It is Best used to mow around obstacles and nance, a low-maintenance vegetation
Knowledge of the biological interactions the engineering work and focus on the therefore important to mow the grass in in areas that are difficult of access or not suited to local conditions can be achieved
Biological measures are used to between the soil, the competitive strate- transition band in the track vicinity. SBB the zone of extensive maintenance at suited to larger equipment. by selective thinning out of trees and
shape and treat the transition band gies of plants and their reaction to speci- experience shows that the transition band least once a year. Longer intervals will shrubs in compliance with Swiss standard
and the bank so that only such plants fic types of treatment is also useful for should ideally be sown with seeds adap- lead to the growth of wooden plants and Motor mower «SN 671 560». Preference is given here
can grow on them as do not interfere new line constructions, where, depending ted to local conditions as soon as possi- a higher proportion of wood in the plant Used mostly on smaller or sloping areas to slow-growing and small species.
with railway operation and mainte- on the situation, measures to prevent ble after completion of the engineering material that the mower encounters. The and to protect valuable plant stands.
nance. erosion are necessary. work (preferably in the spring). Leaving latter results in a higher consumption of Particularly undesirable plants can be
While constructional measures mostly these areas for spontaneous plant cov- energy, and a lower performance per Rotary mower removed by selective weeding by hand,
mean a change of the soil structure, Apart from constructional measures that erage will often result in a large propor- surface unit. Problem plants like Japanese Mowing device mounted on a tractor. The hoeing or cutting. Especially in shady
shaping work means the sowing or are unavoidable in problem areas in tion of problem species. This can happen knotgrass, brambles and reeds tend to cuttings are usually left on the ground as places such as wooded recesses, seed-
planting of non-interfering species, the long term, biological maintenance especially where new earth containing spread far more quickly if mowing mulch. It is important that the cuttings lings of trees or bushes are often to be
appropriate maintenance, selective remains a standard activity for railway seeds and particles of plants able to intervals are longer. should not be spread onto the ballast or found, which should be removed in
weeding of the bank, removal of companies. To perform it optimally, it is germinate is spread in the area bordering verge. A newly-developed bank mower autumn and winter.
shrubs and trees and regular mowing wise to work with an official green area on the bank. On the other hand, sponta- Mowing is effective for up to a year caters to this requirement by blowing the
or grazing. All of these works require cadaster. neous natural plant coverage should against growth of brambles, traveller’s cuttings out into the bank area. The production of a green area map or
adequately trained specialists. generally be encouraged in the zone of joy, bushes or trees on a soil favourable cadaster can be extremely helpful for
With the exception of mowing, the extensive maintenance. Banks that are to meadow plants. Regarding horsetail Self-propelled rotary mower planning and implementing special
Influencing the composition of the plant costs of biological measures cannot liable to erosion and subsidence should and reeds, this effectiveness lasts roughly All-terrain, 4-wheel drive vehicle with a environment-friendly measures such as
species requires knowledge in the fields be stated with any accuracy because however be planted quickly (see SBB half as long. For this reason, during the front-mounted mowing device. Possible these.
of: of the big differences between the handbook «Grünflächen bei Bahn- growth period at least one to two sideways slippage can damage the bank.
local conditions. anlagen, Projektierung», chapter D mowing operations a year will be needed Cost: 1 - 3 sfr./square metre
➠ soil quality; «Begrünung»). on the transition band. Rotary mower with suction device
➠ habitat requirements and the ability This is similar to a standard rotary mower,
of single plant species to compete Cost: approx. 5 sfr./square metre With a greened verge (see page 28), but fitted with a suction device to collect
with others; note that this indication applies only the cuttings in a mobile container. To
➠ plant reactions to specific treatment if no herbicides are used in the area prevent further enrichment of the humus
methods. Loose vegetation and not being mowed, as herbicides will content of ballast and verge, use of
sufficiently frequent mowing destroy the plants that compete suction equipment is recommended The picture clearly shows the
For example, the different competitive promotes the growth of naturally with horsetail and reeds. above all in cuttings and on the mountain different control methods used
abilities of plants can skilfully be used to unwanted plant species in the Horsetail, which is resistant to side of sloping terrain. Usually, only for areas of intensive and of
good effect. Since regular mowing is transition band (e.g. thistles). Glyphosate, will even benefit from cuttings from the band of greenery extensive maintenance.
harmful to those plants that send out the operation. immediately adjacent to the ballast are
runners, these species will be superseded removed by suction. However, to protect
by others less or not at all affected by In this connection it is mandatory to animal life in the bank, this procedure is
such a measure. To ensure that this oust- pay attention to the fact that the use not recommended in the zone of
ing mechanism functions properly, the of herbicides with few exceptions is extensive maintenance.
local conditions (particularly the soil com- forbidden in the bank area!
position) must be such as to encourage Cost: 0.2 - 0.7 sfr./square metre
the growth of the favoured plant species. Below, an overview is given on the most
common mowing methods used by the
Wet, clayish and compacted soils, which railways:
favour the growth of problem plants
penetrating underground into the ballast Scythe
bed like horsetail and reeds, should either Purely manual work, noiseless, but with
be replaced to a sufficient depth near the low surface area coverage.
track, or drained, or improved. Only in
this way, problem plants can be super-
seded. A welcome advantage here is the
14 15
Mechanical Ballast cleaning Suction method Mechanical Manual
weeding weeding
Measures If the ballast bed is to remain free of A suction device mounted onto a road- There exist a few machines that can weed There are several manual weeding The effect of weeding will depend very
weeds in the long term, then ballast rail vehicle removes unwanted material and clean the verge, but none of them methods. For example, the plants can be much on the plant species, the thickness
cleaning is an important measure. A (cigarette ends, organic waste, leaves, has been heavily tested as yet. By cut off or hoed out level to the ground of the plant cover, the time of year, the
Plants are removed from the track
ballast bed that is clean and dry through- humus, sand, etc.) from the surface of the mechanical peeling of plants from the with a sharp implement. Either all plants local growth conditions, the weather and
area by mechanical measures.
out will not permit plant growth, though ballast bed. This operation thus contri- surface during dry summer weather, it is are torn out, or particularly undesirable the seed reservoir in the soil.
Therefore these measures belong to
propagation of problem plants from butes to the prevention of weeds on possible to defer the constructional species only (with the roots if possible).
those attacking the symptoms. With
below ground is still possible. railway tracks. Since the vehicles move renewal of the verge by several years. It is This produces more or less loose hollows Cost: 4 - 5 sfr./metre
ballast cleaning and suction devices,
very slowly and therefore occupy the line however important that the material in the verge which can further encourage
not only the plants themselves are
The ballast cleaning machines used on for a long time, they are only used in and removed, which is rich in humus, is not seed germination. Some weeded areas
removed, but also the dirt which is
the SBB network pick up the dirty ballast around stations and on lines with little left lying on the inspection walkway or are therefore treated with Glyphosate
the basis of their existence. As such
with a conveyor scoop or an excavator traffic. For operational safety, it is also the ballast bed. This procedure can only when the new plant cover has reached a
there is also a preventive dimension
belt. The material thus extracted is passed very important that compacted ballast be used on gravel verges and surfaces. height of 5 to 10 cm.
to this kind of work. Although both
through a mechanical cleaning system in does not become loose as a consequence Daily performance is 1 to 2 km.
these procedures are used first and
which the fine particles are sifted out. The of this kind of treatment. A weeding experiment on a limited area
foremost to guarantee track stability,
cleaned ballast is then spread back (eradication of common cranesbill in
they fulfill also an essential role in
beneath the track. Cost: 4 - 5 sfr./metre Cost: with machine operator, but ballast) showed that the hourly perfor-
vegetation control.
without lookout man mance per person was approximately 30
A good ballast cleaning can be effective approx. 1 sfr./square metre square metres. A thick growth of horsetail
from 20 up to 40 years, depending on was removed from the ballast shoulder,
local circumstances and traffic density, if and the performance was about 33
the adjacent verges and banks have been square meters. On larger areas however,
built and planted in compliance with the it will not be possible to achieve this level
rules, and are properly maintained. of performance.
Cost: 300 - 500 sfr./metre
Manual weeding is comparatively
Weeding machines for verges costly, but it allows a selective
By removing dirt and rubbish have not yet been tested on a approach. Its effect varies quite
A ballast bed that is clean from from the ballast, a preventive large scale. Their use is only much. Especially in the case
top to bottom, largely prevents contribution is made to suitable if combined with other of the horsetail, the effect
plant growth. vegetation control. measures in the track area. does not last long.
16 17Chemical Compared to the soil herbicide Atrazine Back-pack spraying Spraying train
that was in regular use on the railways Leaf herbicides like Glyphosate
up to 1989, the leaf herbicides containing cannot be used preventively, but
Measures the agents Glyphosate and Sulfosate, that are applied directly to plants of
Some 80 – 90% of all spraying on SBB is
done using back-pack sprayers.
Only a few motorised spraying units are
still in use on SBB. These units are
are permitted today, bind better with the existing vegetation. The effect of mounted on small wagons («Sputniks» )
ballast and verge material where they Glyphosate depends on the With a constant spray pressure of 2 bars and pushed by a light rail motor tractor.
Use of chemicals to remove individual degrade relatively quickly. Unlike with the growth conditions, the presence of and an average walking speed of approx. They are designed for an operational
plants from the track area is a deli- soil herbicides, only small quantities of problem plants with underground 1 m/s, about 50 litres of fluid will be spraying speed of 15 km/h. A dosage
cate matter, considering their impact leaf herbicides are used now. These are propagation, the seed stored in needed per hectare. device (Dosatron) provides a constant
on nature and the environment. The absorbed by the plants through their the soil and the number of seeds mixture of concentrate and spray water,
operators must therefore be experts green parts only and therefore cannot be brought in by the wind. This effec- Because of the fine spray mist, there is a which avoids leftover fluids and means
and act responsibly. For this reason, used preventively. tiveness can last for anything considerable risk of the sprayed that work can be stopped and started
use of chemicals on SBB is governed between 10 days and 2 years. substance being blown away by the wind. again at any time. The risk of water
by instructions «Chemische Vegeta- In principle, the use of herbicides is Work should therefore be stopped during pollution from spillage is very low.
tionskontrolle bei den SBB», in which banned in the banks alongside the tracks. In conditions that are not favou- strong winds.
detailed, binding rules are set out. An exception is the treatment of rable to growth, with treatment Cost: 0.25 sfr./metre
One specific requirement limits the individual problem plants where these carried out at the right time and It is essential that the fluid be applied to
working with herbicides to staff in cannot be controlled by other measures, proper tending of the adjacent the plants only, as otherwise the
possession of a valid authorisation, such as regular mowing. land, Glyphosate-based weed treatment will not be effective and can
or acting under the guidance of an control can be successful over a cause damage to adjacent property. The
authorised person. Apart from further Use of Glyphosate has been optimised for longer period. It is recommended direction of the spray nozzle must
restrictions, the use of herbicides railway needs, including back-pack that the intervals between appli- therefore constantly be adjusted to the
outside the track area (ballast and spraying devices and spraying trains. cations are varied (see SBB area being treated – standard practice for
verge), in the vicinity of rivers and instructions «Chemische Vegeta- decades in viticulture and horticulture. It
lakes, and in ground water protection tionskontrolle bei den SBB») to is also important that the spray always be
zones S1 and S2, is forbidden. ensure that the vegetation does directed towards the ballast bed from the
not have a chance to adapt to the exterior.
The restrictions and bans on herbicides, changed conditions.
necessary to protect human health and
An SBB back-pack spray team will treat
the environment, are determined every
an average of 11 track kilometres per
year by the Federal Transport Office (BAV)
day.
in directives for all railways holding a
federal licence (BAV, 2001).
Equipment investments (not including
vehicle and training) amount to around
Areas in which the use of herbicides is prohibited For further information, please refer to 2000 sfr. per team.
the SBB instructions «Chemische
Track sections Other railway ground Vegetationskontrolle bei den SBB».
Cost: 0.2 sfr./metre
● ground water protection zones ● trackside and roadside banks
S1 and S2 ● forecourts, parking and storage
● areas with protection status areas
similar to ground water ● platforms
protection zones S1 and S2
(private drinking water sources, ● loading platforms
seepage and drainage installations) ● roadways and paths
● in a buffer zone of 3 m alongside ● roofs
surface waters An operation that looks
● terraces
● bridges comparatively easy but makes
● directly in and in a buffer zone heavy demands on the expertise
● track to be renewed before the of 3 m alongside hedges or of the staff.
end of June of the current year small woodlands Correct and responsible
spraying of leaf herbicides
requires in-depth training.
18 19Thermal Burning Infra-red Selection Cost factor Environment factor
devices
Measures Burning of plants with a propane burner Combustible gases like propane are
Criteria From a financial point of view, it is the In vegetation control today, not only
similar to those used as point heater on currently the cheapest source of energy long-term cost-effectiveness of the cheap, but also environment-friendly
SBB is admittedly effective at the begin- for producing the type of infra-red that various procedures that is of prime measures with a lasting effect are requi-
Thermal methods of vegetation The overview given on the following
ning, but this tends to be short-lived since can be used to destroy plants. As the interest. Constructional measures for red. This is why priority is given to
control such as infra-red (IR), burning, pages shows the benefits and draw-
without a supply of heat to convert the heated plates that radiate the infra-red example are extremely expensive but also constructional and maintenance-related
hot steaming and hot water treat- backs of different vegetation control
liquid propane into gas, the pressure soon rays need to be placed as close as effective and have a long-time effect. In measures having a preventive effect. This
ment destroy plant cells through the measures in regular use on railway
subsides. possible to the surface, the area must be most cases, they also have other, positive does not mean, however, that the proper
effects of heat. Apart from the high grounds today. When deciding on the
flat and free of obstacles for the mobile side-effects at operational level. use of permitted leaf herbicides to elimi-
energy consumption with the atten- best procedures, not only the tech-
The coverage achieved in an experiment equipment to pass. nate existing vegetation is fundamentally
dant financial and environmental nical pros and cons should be taken
reached 0.6 square metre/minute with For vegetation control, top priority goes less environmentally friendly than non-
consequences, also the generally into consideration, but also the
propane consumption of around 222 g The models on the market include devices to preventive measures. For this reason, chemical procedures. Ecological audits
short effect of these measures make longer-term consequences in regard
per square metre. with a constant surface coverage (such as the corresponding requirements need to have shown that many measures that
them highly questionable. to costs and environmental impact.
Thermflex) and others whose coverage be included into the planning and project- may appear environmentally-friendly at
diminishes after a short period of use ing phases of construction projects. first sight are in fact more damaging
Basically, only those parts of plants that Although the constructional measures
depending on the temperature (such as Incorporating vegetation-specific con- because of their high energy consump-
lie above ground can be damaged by have clear benefits, they can, for reasons
Puzzy Boy). cerns in the planning phases can bring tion, than the carefully targeted use of
thermal measures. Their effect is therefore of cost, normally be applied in tandem
substantial cost savings, and later save the leaf herbicide Glyphosate.
mostly short-lived and for plants that with scheduled renewal work only. This is
costs for direct action in vegetation
form runners or have strong roots, the why, in order not to discontinue railway
control. Methods attacking the symptoms are by
impact is particularly slight, as was clearly The costs associated with thermal methods cannot currently be determined operation, recourse must be taken to
no means a panacea that can meet all
shown in several trials. to any degree of accuracy. Once the ongoing SBB test with hot steaming is other measures that tend to attack the
The same goes in many respects for the the financial, operational and environ-
completed, the corresponding figures should become available. symptoms only. It is precisely with these
maintenance work needed for all types of mental requirements imposed on vege-
Ecological audits have shown that to methods that particular attention must be
railway installations. On a well-main- tation control. Quite the contrary – with
obtain with thermal measures the same paid to environmental considerations. So
tained line, the time and money needed the increasing age of the railway installa-
degree of vegetation absence as with whilst grasses and herbs can be success-
to remove unwanted plants will be con- tions, also the number of treatments
chemical measures, 5 to 14 times more fully treated with the comparatively
siderably less than on a line where needed each year to clear the track area
energy is consumed (a satisfactory result cheap herbicide Glyphosate, the same
upkeep is poor. of vegetation increases. This means that
from thermal measures requires several substance can under certain circumstan-
the most energy is expended on surfaces
applications). This is also the main reason ces encourage the spread of horsetail.
with the best growth conditions. The ratio
why this method has hardly been used in
between energy use (high environmental
Switzerland to date.
impact) and benefits obtained, constantly
deteriorates. However, in the interests of
Apart from the methods presented here,
railway operations, we have no option
there are others which for railway appli-
but to resort to these measures. At the
cation are as yet only in a trial stage (e.g.
same time, it might be worth considering
hot steaming).
where a certain amount of growth can be
tolerated until the next renewal
operation.
Particularly young plants with as Before deciding on one measure
yet only a few leaves can or another, the situation should
relatively easily be eliminated be carefully considered and the
with thermal methods and impact of the various options
corresponding expense of energy, analysed. What is supposed to be
however the duration of effect is the direct path does not always
very short. And the real problem produce the desired result.
plants such as horsetail cannot be
eliminated in this way.
20 21Comparison of Different Measures
Procedure Benefits Drawbacks Optimum range of use Synergy effects
Constructional measures Bituminous weed barriers Optimal for keeping vegetation away from the ballast Line must be closed during installation Best installed during construction or complete Protects substructure and the natural subsoil
bed and the verge; stops underground incursions by renewal from water penetration, giving longer life as a
problem plants result; cost-effective construction method
Verge design Ballast bed lastingly free of vegetation; reduces Line possession or hindrance Everywhere between the ballast bed and the Protects substructure and the natural subsoil
mower cuttings in the verge; herbicide use can be bank from water penetration, giving longer life as a
drastically reduced result; cost-effective construction method
Lateral barriers Ballast bed lastingly free of vegetation; reduces Line possession or hindrance Everywhere between the ballast bed and the Easier access to inspection walkways; lateral
mower cuttings in the verge; herbicide use can be bank drainage of the ballast bed, depending on
drastically reduced location and structure
Porous concrete barriers Ballast bed lastingly free of vegetation; reduces Line possession or hindrance; possible During the renovation of existing railway lines; Drainage, leading also to better trackbed
mower cuttings in the verge; herbicide use can be clogging of drainage systems as lime is dams where space is confined stability, stable bank shoulders with little
reduced; cheap! washed away available space; inspection walkway
Insertion of foils Long-lasting barrier to plant growth; reduces mower Line possession or hindrance; can hinder In the verge (especially at the renewal of existing Easier access to inspection walkways
cuttings in the verge; herbicide use can be drastically lateral drainage lines and in ground water protection zones)
reduced
Biological measures Greening Suppresses problem plants, prevents rapid spread of Line possession required where access from After construction work, when plant cover in the Protection of nature and countryside; well-
plants with runners; protects against erosion outside not possible transition band is patchy or absent; in bank areas maintained bank (image); protection against
prone to erosion and slippage erosion
Mowing Suppresses problem plants, prevents bush growth and Line possession required where access from In meadowland and poorly-stocked areas; in the Protection of nature and countryside; well-
runner incursions; protects against erosion outside not possible transition band and adjacent bank tended bank (image); protection against
erosion
Selective embankment maintenance Treatment suitable to local conditions; flexible Requires knowledge of existing vegetation Wherever necessary, in the extensive Protection of nature and countryside (protec-
application, not subject to weather conditions maintenance area, in areas with bushes and tion of rare plant species possible); stabilises
hedges the bank and improves operating safety
Mechanical measures Ballast cleaning Lasting effect against seed-dispersion weeds Line possession required; cost-intensive Necessary throughout to ensure longevity for Gives an opportunity to make minor
tracks adjustments of the track level; elastic
positioning of rail surface
Suction method Slows the formation of humus; specially effective Line possession necessary; no depth action; Removal of surface material (humus, cigarette Removal of dirt in station areas (image)
against seed-dispersion weeds cost-intensive ends, rubbish, leaves, etc.) especially in station
areas and on lines through forests
Mechanical weeding Longer absence of vegetation in the ballast; reduces Line possession necessary, cannot be applied In the presence of humus on compacted gravel Easier to walk on inspection walkway
mower cuttings on the verge; use of herbicide everywhere; cost-intensive verges (cuttings, slopes, ground water protection
drastically reduced zones)
Manual weeding Flexible application, not dependent on weather cost-intensive; often short-lived effect only Selective removal of individual plants, clearing of Easier to walk on inspection walkway; removal
conditions, energy-saving, low environmental impact small areas (e.g. in ground water protection of plants reduces humus formation
zones)
Chemical measures Back-pack spraying Cheap, line possession not necessary, energy saving, Requires specialist knowledge; effect depends On ballast shoulder and verges; no preventive None
targeted application on location and weather; encourages growth effect
of resistant horsetail
Spraying train High surface area coverage Line possession necessary, cost-intensive; Big trackyards with little traffic (e.g. shunting None
dependent on weather conditions yards)
Thermal measures Burning Easy to implement Poor propane consumption to effect ratio; Application not recommended None
destruction of plastic components; danger of
fire; air pollution
Infrared devices Small, lightweight equipment Limited impact on luxuriant growth; danger of For minor growth (seedlings) on easily-accessible, None
fire; risk for plastic components; air pollution level surfaces free of obstacles
22 23Common Horsetail Cranesbill, Japanese Reeds Brambles
Herb Robert Knotgrass
Weeds in the
Track Area
Most of the plants to be found in the
track area propagate by seed disper-
sion. Many are perennials and diffi-
cult to control from the second year
onward (e.g. creeping thistle). For this
reason alone, measures that prevent
plant growth (by taking away their
supplies of water and nutrients, or by
setting up competition with other,
comparatively harmless species)
should be given particular considera-
tion. Furthermore, many problem
plants grow on soil structures that
are also bad for railway operation,
and in areas where soil replacement
would be recommended anyway. The Equisetum arvense Geranium sp. Reynoutria japonica Phragmites sp. Rubus sp.
following overview looks at five typi- Perennial, with much-branched, extensive Annual or biennial, with a thin taproot, Perennial, thin-walled stems up to more Grows up to 4 metres in height; Perennial; runners up to 7 metres long
cal problem plants commonly found root system reaching down to a depth of grows to a hight of 10 to 50 cm; has than 3 metres tall and 4 cm across, vulner- perennial, with long underground suckers grow out from the rootstock. From early
in the track area and outlines the 1 or 2 metres. Propagates through rhizo- reddish flowers and produces seeds from able to frost. The rapid growth stops end over a metre deep. Spreads through August, their ends grow back into the
best way to deal with them. mes and sprouts. Penetrates the track April to October; propagation with large of May. The root system, serves to store rhizomes and suckers, to a lesser extent ground and form new rootstocks. Propa-
area from below. Sandy or gravelly cover- numbers of seeds. Spreads rapidly especi- nutrients and from its buds, stems grow by seeds. In soils with a poor load-bear- gation by runners growing into the soil,
ings and old ballast dumps encourage its ally in the ballast of shunting and mar- above the ground. It spreads out below ing quality, damp and generally rich in root pieces, also to some extent by seeds.
growth. shalling yards. Hardy, germinates in late the surrounding vegetation at a rate of up nutrients, reeds will penetrate into the Incursion into the track area by spreading
summer where damp persists in fine- to 2 metres per year. Reproduction takes track area below ground from untended from unmaintained banks above the
Control: Complete removal can only be grained matter and impurities of ballast. place mainly via the rhizomes, and also banks. surface.
achieved by constructional remediation of It spends the winter there as a hardly (though rarely) via the stems. In poorly
ballast and verge. If this is not possible perceptible seedling that grows up fast in maintained banks and also on gravel and Control: Annual mowing of greened Control: Annual mowing of greened
and the growth is problematic, horsetail the spring. Growth of cranesbill will old ballast areas, it will supersede the verges and adjacent transition bands in verges and adjacent transition bands, in
growing in the ballast can be torn out by increase the humus content of the ballast. smaller, established vegetation and grow June/July (and again in mid-September if June/July (optimal time), and again if nec-
hand. This is expensive and must be re- into the track area from below. necessary). Subsequent growth in the essary in mid-September. Subsequent
peated several times a year, as the roots Control: Glyphosate treatment, after verge should be treated with Glyphosate growth in the verge can be treated with
generally remain in the ground and the local inspection, must take place without Control: Must be cut back to near when knee-high from the end of August. Glyphosate from late August.
plant regrows quickly. fail before plant reaches seeding maturity ground level in early August. In Septem- Good drainage of the track area (possibly
in the spring (approx. late April). At this ber, when the stems are around 40 cm in combination with lateral barriers). Mowing in June/July is necessary, as
Treatment with Glyphosate should be period, only areas where cranesbill pre- high, they are treated with Glyphosate, by this time, the larger part of the
avoided by all means! It has no effect dominates should be sprayed, as Glypho- and the following year, when the new Mowing is necessary in June/July, as winter reserves has been taken up
on horsetail and even encourages its sate has as yet no effect on some other growth has reached about the same by this time, the larger part of the from the roots and the subsequent
growth by eliminating competing plant plants. In cases of thick growth, a second height, mow it or treat it again with winter reserves has been taken up growth is much less strong. Glypho-
species. A thick growth of grass adjacent treatment is recommended before the Glyphosate. Further propagation can be from the roots and is not available sate treatment alone will seldom be
to the verge to compete with the horse- next generation goes to seed. prevented by regular mowing (five to six for lateral propagation. fully effective.
tail will stop its spreading quite effectiv- times a year) and adjusting the soil condi-
ely. Treatment after seeding maturity will tions (possibly in combination with lateral
actually encourage the spread of barriers).
Deep-seated drains and compact cranesbill!
To achieve sustainable elimination,
asphalt layers are the most effective
specialist advice must be sought.
measures against horsetail.
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