Safety performance assessment of extra-urban road interchanges: a review of the Italian Road Inspection methodology

Abstract

In 2019, the Italian Ministry of Infrastructures launched a program of safety inspections along the roads of the Italian TEN network. The result of the ministerial program consists in multiple assessment reports about defects or hazardous conditions of the inspected infrastructures. To develop this program of inspections the methodology proposed by the Italian Guidelines, according to the EU Directive 2008/96/ CE, provide for the compilation of two types of Road Safety Inspection (RSI) reports: the first one referring to continuous segments of the network, the second one focused on singular sites (intersections, interchanges, tunnels). In this paper, moving from a critical analysis of the RSI report scheme for the safety rating of interchanges - applicable in case of insufficient, or unavailable crash data -, a more effective filing system is proposed, to objectively assess the safety performance of these singular sites. In detail, the Italian guidelines RSI report - based upon a qualitative score (rating 1-3) for aspects related to location, traffic, geometry, characteristics of signs and safety systems - is revised according to data reports developed for similar objectives by other institutions - as the FHWA - and integrated according to the Human Factor Safety Evaluation Method (RSE_HF) suggested by the PIARC in 2019. In this way, the revised report combines geometric and maintenance information with the assessment of the road characteristics leading to driving mistakes. In the second part of paper, the revised RSI procedure is applied to three different interchanges previously inspected according to the present Italian guidelines. A comparison between the results from the ministerial forms and from the suggested methodology is conducted.