# Road Safety Management of Uncontrolled Access Points:
## 1 Introduction
[16] reported that access points with an excessive width are associated with higher accident rates; this situation is due to the potential driver confusion regarding the correct position of the vehicle; in addition, in urban areas, pedestrians are longer exposed to vehicular traffic [18; 19; 20]. On the contrary, a narrow width helps to reduce the speed of the vehicle entering the access with a right turn manoeuvre, thus increasing the relative speeds between the through-traffic and turning vehicles [17]. Generally, also a decrease in the entry radius is related to a reduction in the entry speed [17] whereas a larger radius allows for easier ingress and egress manoeuvres [18]. Several disadvantages are related to larger radii such as the reduced visibility of pedestrians, longer pedestrian crossings, and higher operating speeds [21]. A small radius can be useful to discourage left turns and to reduce right-turn approach speed [22]; nevertheless, under these conditions, some issues may be related to the vehicle encroachment into adjacent lanes and the higher decrease in speed for entering vehicles. Furthermore, an improper radius can cause vehicles to complete the manoeuvre in the opposing lane of traffic; this situation is more critical for industrial/commercial access points [18]. Besides the negative effects on the safety level linked to the uncontrolled localization of access points, and the formation of potential conflict points between vehicle trajectories, it is necessary to mention the effects on operational performance which are frequently related to the reduction in the capacity and average speed of the main traffic flow [23]. The speed reduction for a through-vehicle can range between 7 and 23%, depending on the driveway activity [24]. The control of access speed and density is part of a broad set of measures (access management) aimed at the systematic management of access points both during the planning and operation stages [25]. Furthermore, these measures are aimed at reducing conflict points, the increase in spacing between accesses, and improving operational performance by minimizing delay times and queues [26; 27]. Access management techniques improve traffic safety: the accident rate of roads with full access control is lower than 25-50% of those at locations with no access control [28]; accident frequency could be reduced by 50-70% according to AASHTO [2; 29]; for urban and suburban networks, the reduction in accident rates is estimated to be approximately 40-50% [30]. In this paper, the focus is on uncontrolled accesses, namely, access points without traffic lights, stop signs, right-of-way, yield signs, or right-turn acceleration/deceleration lanes. The absence of adequate geometric design and access management measures translates into the transformation of these points into accident hotspots [3; 31]. The international context of standards offers several approaches to uncontrolled accesses management; conversely, Italian regulations do not establish specific guidelines for the geometric and functional design of these road infrastructure elements. The main objective of this work is to explore the correlation between the geometric and physical features of accesses and the safety of drivers and pedestrians. The analysis includes the results obtained for a selected case study, the state road SS18, an important element of the Southern Italy road network. The study is based on the characterization of 857 accesses by managing several qualitative and quantitative variables by GIS tools (geographic information system). The following section examines the categorisation and characterization of the variables collected for each access point. Access points include private accesses (driveways) and industrial/commercial accesses (shops, hotels, service stations, etc.).