The Smart Road concept has marched into the agenda of many sector players and infrastructure is, as never before, at the centre of design that aims to improve the quality, safety and use and intends to make it able to generate data and services to make the mobility of goods and people easier, facilitating and simplifying transport.
It is well-known that the digital transformation of transport infrastructure is both an essential factor for relaunching the sector and an enabling factor for sustainable, intelligent and inclusive growth for the whole of Italy. The existence of an indissoluble trinity – infrastructure, the vehicle and the user, all distinguished by misaligned states of the ‘technological’ art, with incomparable creation times, necessarily conflictual and with different attractions, is equally well-known. In this scenario, the approach stating that anything can be done by simply adding intelligence to the streets, i.e. the idea that has led to considering a Smart Road as a line with a cable duct for optical fibre, some new coils, sensors or a new aerial, is an easy commonplace to avoid, worth the risk of obtaining not only a profoundly irregular technological level of mobility but, more than anything else, a short life of the planned investment.
On one hand, the production of increasingly ‘smart’ vehicles is, luckily, inescapable – just think of the notable development in and considerable capital allocated for automatic driving or the ‘detection & prediction skills’ of vehicles; on the other, the environment in which these vehicles operate must be made highly communicative. Moreover, these features must be achieved extensively, easily, with low obsolescence and contained installation and maintenance costs to ensure that they don’t remain isolated pilot projects, dotted here and there.
In the face of this, we mustn’t limit ourselves to the integration of complex systems into streets, for very obvious technical, economic and commercial reasons, the real intelligence must stay in the vehicles which, at present, as many of us have found out, already have systems based on radar technologies (e.g. the collision prevention system) and/or ‘photogrammetric’ type acquisition and recognition techniques (e.g. the lane invasion control system). Although such systems still don’t operate perfectly in certain weather conditions and so can, therefore, be improved, road elements (signs, indications, etc.) are the variable which, with their terrible state of repair or incorrect positioning, have the most impact on the ‘fail rate’ of this equipment.
A concept of Smart Road is thus outlined with similar theories focussed on the use of an information acquisition system based on the reading of exclusively passive roadside elements, able to gather information and data on vehicles through radar systems already installed, sharing this directly at precise points of the infrastructure via hot spots, found in lower numbers and at strategic places (toll booths, motorway service areas, stop areas, car parks or precise stretches of road). Not a banal network of sensors but elements connected to normal road installations (signs, safety, etc.) easy to create by those who already produce these elements, without the introduction of additional process suppliers or system integrators. Such a technology already exists and it can be usefully employed in all stages of life of the infrastructure and driving experience – from info-mobility systems to sensors and systems measuring the state of the infrastructure (bridges, viaducts and tunnels), to vehicle-infrastructure connection technologies with a view to automatic driving.
The technology consists of a specially produced thin film to apply to the surface, for example, of road signs. This film falls within the definition of metamaterials, i.e. an artificial material constructed using metal-dielectric engineered structures a lot smaller than the wavelength used for the ‘reading’ with which properties not found naturally, such as dielectric permittivity, negative magnetic permeability and negative refraction index, can be synthesised. These innovative means allow the propagation of electromagnetic fields, and so the response to a radar signal, to be checked and can be both three-dimensional and two-dimensional structures, and are commonly described as ‘Frequency Selective Surfaces’ (FSSs). FSSs are planar elements with the interesting feature of letting electromagnetic waves in a certain range of frequencies pass unchanged, reflecting all the others, thus allowing, for example, road signs to respond with a different ‘code’, according to the type of sign. Both volumetric number methods, like FEM and FDTD, or special MoM codes are commonly used for the analysis of the FSSs.
Although analysis by these techniques is at the overall project level, the results are extremely accurate and do not require further variations once the size of the item the technique must be applied to and the ‘message to send’ have been established, thus leaving the producer of the element completely free and independent in the production stages. In conclusion, it’s a technology that can contribute to a gradual digital transformation of the road network, making it suitable for ‘conversing’ with the new and latest generation of connected vehicles, allowing use of the most advanced levels of automatic assistance for driving in any condition and obtaining, by reflection, both less road traffic and a significant reduction in road accidents.
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