The interventions of maintenance of the territory takes on particular value when carried out on those strips that are interposed between the areas destined to specific services and the rural, semi-natural or natural ones.
They are mostly related to road edges and railway embankments, to areas enclosed by roads, to the banks and embankments of drainage canals and of the river network in general, to the edges of human settlements and to the areas of respect of cable ducts; all areas that require interventions aimed at controlling the development of vegetation and, more generally, at maintaining territorial standards that vary depending on the environmental context. Among those most relevant to the context we can point out those aimed at reducing erosion and consolidating the soil to avoid landslides and landslip in general.
On the whole, the maintenance of the margins aims at maintaining the functionality of the main body which, in fact, is often an artery that develops for kilometers and kilometers inside the territory. On the ways to maintain this functionality there has been a progressive and constant evolution that has led, especially abroad, to change the standards of interventions. In particular those aimed at controlling the herbaceous vegetation today tend to be less destructive and rather pursue the goal of encouraging the establishment of a more resilient flora of the multi-year type to the detriment of the annual one. The latter is often ruderal, often allochthonous, often fast-growing and unable to provide the stability and consolidation required throughout the year. Today, however, we tend to consider the intervention, for example along roads or the banks of canals, similar to those carried out on an agricultural lawn, where, however, the product is not removed (except in very rare cases). This objective can be achieved, for example, by raising the cutting heights to values no lower than 50-60 mm.
New expectations
However, the management of vegetation in these marginal areas is now loaded with new expectations that derive from the recognition of the ecological role they play and the ecosystem services they could provide. In fact, they constitute ecological systems that can help to improve the quality of the territory and preserve it from hydrogeological risks. All this has a great value if we consider that, unexpectedly, these marginal areas represent more than 20% of the floral richness and diversity of our territory (biodiversity reserve) and that in many cases they represent ecological corridors for many species. In rural contexts, the biodiversity along roadsides and water is higher than that of neighboring cultivated fields. This model therefore proposes a differentiated management of green areas that privileges mechanical interventions, leaving out, as far as possible, chemical and physical means of other nature. It can contemplate a reduction in the frequency of cutting/shredding, to allow the vegetation to go to seed, or more frequently a variation in the useful periods of execution, an increase in cutting heights even above 100-120 mm to preserve the microfauna and the type of vegetation unable to withstand the cut, the prohibition to operate in periods of nesting or flickering. Mixed solutions can be applied, with the identification of portions subject to a high intensity of cutting (3-5 interventions) and areas further inland and therefore more distant from the work to be safeguarded, subject to only 2 or 3 cuts per year or, at most, to a single annual cut, adopting also diversified cutting heights.
It should of course be remembered that grass cutting is carried out to preserve the integrity of the work and its full functionality. In the case of roads, safety conditions are guaranteed when motorists are assured of visibility on the road signs and the route. For this reason, the frequency of mowing the safety strip of the roadside depends on the vigor of the regrowth, that is on the speed with which it grows back. The intervention must be carried out when the grass reaches a height of around 25 cm, in any case no more than 40 cm and in any case before it interferes with the visibility of the reflectors placed on the guard-rails or other elements of the road signs.
Late chopping in the part furthest from the road is carried out in autumn or late autumn (lengthening the working season) thus allowing the completion of the reproductive cycle of the plants with the production of seed and that of insects and other microfauna.
The equipment
This diversification is also possible thanks to the technological development of this category of equipment and to the wide range of fittings available today. Limiting the analysis to the category of with articulated arms, it must first be pointed out that, when coupling them to a tractor, it is necessary to consider the weight of the tractor rather than its power. In fact, stability during work can be compromised when operating at maximum extension of the arm because, in this condition, the weight of the cutting unit can create a tilting moment due to the possibility of extending it considerably even along the horizontal plane. The extension varies in fact from about 3 to 20 m and more.
In this regard, the range of action of the brushcutter must be evaluated, which depends on the maximum extension it can reach not only on the horizontal and vertical planes (the latter, however, is of interest only for equipment intended for hedge pruning), but also on different oblique planes. In this case it is necessary to evaluate the inclination at which it is possible to operate both above and below the horizontal plane, on which the possibility of working depends on both the base and the top of the embankment or slope.
The particular geometry that normally characterizes the articulated arm gives the operator the possibility to place the brushcutter in a very wide range of positions, among which the one defined as wheel flush allows a quick completion of the intervention in all operating situations. In this way, the operator can complete the shredding operations by keeping the tractor close to the roadside and limiting the hindrance to vehicular traffic.
In addition, the brushcutter is equipped with a self-levelling system which allows its position to be adapted to the profile of the ground. In this sense there are considerable differences since this parameter varies between 60 and 235°.
Power absorption depends above all on the size of the chopping unit, which generally does not exceed two meters and more often is around 1-1.5 m and normally does not exceed 100 kW. This can be equipped with different types of rotors and knives that allow to adapt the machine to the vegetation. A rear roller ensures that the set cutting height is maintained.
It is also very important to analyze the safety devices that allow to preserve the integrity of the equipment in case of a collision with obstacles, a condition not too remote given the type of intervention.
Equipment intended for the farmer normally has a spring device that acts on the arm allowing it to retract, while equipment intended for use on motorway circuits is equipped with hydraulic devices that speed up the retraction of the implement.
The possibility of reversing the rotation of the rotor, on the other hand, avoids the problems linked to cleaning in the event of flooding, while reversibility allows optimal operation in both directions of travel.
Lorenzo Benvenuti
