Dottorato in INFRASTRUTTURE E TRASPORTI

Titolo della tesi: DEVELOPMENT AND CALIBRATION OF A SIMPLIFIED ROAD ASSESSMENT PROGRAMME METHODOLOGY

The scope of this thesis is to develop and pilot a new simplified methodology for road infrastructures’ safety assessment. The underpinning idea is to rapidly recognize road safety issues connected with road infrastructure characteristics at a low cost and without the specific need for road traffic crash data. The proposed methodology is based on the concept of Crash Modification Factor (CMF), and the common definition given by the combination of key factors such as Danger (the likelihood that a crash can happen), Vulnerability (risk of injury of road users given a crash occurred) and Exposure (amount of “activity” a user is exposed to risk), to calculate a risk index based on the physical characteristics. The main features used to calculate the risk index were: operating speed, median type, intersection type, area type access points, number of lanes, lane width, curvature, grade, surface conditions, delineation, pedestrian crossing, speed management/traffic calming measures, paved shoulder width, roadside severity - distance, sidewalk, facilities of bicycling, motorcycle dedicated lane, bicycle observed flow, and pedestrian observed flow. Risk values are calculated separately for each 100 m road section for motor vehicles, cyclists and pedestrians. In addition, the Global Risk Score (GRS) has been proposed. Five colors represent the risk levels for each road user category and the GRS. Green = very low risk, yellow = low risk, dark orange = medium risk, red = high risk, and black = very high risk. After defining the simplified risk assessment methodology, it has been implemented into software for automatic road risk assessment. The software can be installed on personal computers using Windows or Apple. It allows to input manually some road attributes, while all the others are automatically calculated thanks to automatic video analysis. After calculating the road attributes, the software automatically implements the above-described methodology to calculate the crash risk for the three road user categories and the Global Risk Score. The risk assessment results are provided in two tables (summary attributes and summary risk index) and on a map for 100-meter road sections. Finally, the proposed methodology was tested through a pilot road assessment of 465 km of national highways in Mozambique, 510 km of national highways in Liberia, and 1.220 km of national motorways in Belarus. In addition, it was validated comparing the GRS values and RTC history data on the national motorway M-1/E30 road sections Kozlovichi (Poland border) – Minsk – Red’ki (Russian border) in Belarus.