## 1 Introduction  
Night visibility is a significant issue for people's movements and activities in a town. Night visibility is mainly due to urban street lighting, which has the increment of people's hours of activity as the primary goal. This goal can be achieved by improving the attractiveness of the town and helping citizen's night-orientation, so that people can continue their activities after sunset [1, 2]. Urban street lighting increases the people's perception of safety, improving their visual comfort [3, 4, 5]. Furthermore, a well-designed street lighting system improves traffic management and road user safety, decreasing the risk of road accidents [6, 7]. On the other hand, street lighting service has relevant costs and a great impact on energy consumptions in most municipalities. For example, in the Netherlands, the energy used by municipalities for public lighting accounts for 60% of their electricity consumption, while in some Spanish municipalities street lighting service may account for up to 80% of electricity consumption [8, 9]. Nineteen percent of the world's electricity production is consumed for illumination purposes and 3% of global worldwide electricity is consumed for public lighting [10]. For this reason, it is important to assess lighting levels based on the actual use of roads to avoid oversized lighting systems and light pollution phenomena. A reduction of light pollution phenomena and an improvement of the sustainability of the lighting systems (e.g., contributing to a reduction of the greenhouse effect) is possible with well-designed systems. A well-designed lighting system is planned on the basis of the minimum lighting requirements. Such requirements for roads, established by in force regulations or recommended by specific guidelines, are given as a function of lighting classes, whose selection procedure is mainly based on the intensity of traffic volumes [11]. Therefore, the knowledge of traffic volumes within an urban context is important for the respect of the minimum lighting requirements, to avoid oversized lighting systems and electricity waste. In order to analyse and predict the intensity of traffic volumes in an urban context, there are many techniques. Among these, the space syntax is very effective and accepted by the majority of urban planning and the scientific society [12]. Space syntax, through appropriate spatial indicators, is able to express the intensity and distribution of the traffic volumes in roads of a town. Therefore, it can be used as the basis for lighting planning strategies or for refurbishment designs of roads and groups of roads. Nowadays, in the scientific literature space syntax has already been applied to carry out urban studies and to projects focused on street lighting. For example, in 2017, [PERSON] et al. [13] used space syntax to evaluate public areas from the point of view of pedestrian safety, while [PERSON] et al. [14] adopted space syntax as the basis for a methodology to estimate roads capacity in urban areas. In a more recent study, [PERSON] et al. [15] made a comparison between measured illuminance values and space syntax results for the city of Tehran to establish if illuminance levels were weighted upon traffic levels. In the case that the illuminance levels were too high, they proposed a design phase to reduce energy consumption. The study of [PERSON] et al. [16], although published in 2006, is interesting because it reveals relationships between lighting parameters and spatial properties for some pedestrian roads of the city of Seoul in South Korea. Relations have been analysed for the present arrangement of the roads quite far from design requirements. The analysis shows very low values of correlation between lighting parameters and spatial properties. Nowadays, in the scientific literature analyses aimed at ascertaining and quantifying relationships between spatial properties and lighting levels in urban contexts are lacking.