Development of a Human Factors Evaluation Procedure for Network-wide Road Safety Assessments

This work aimed at the definition of a Network-wide Road Safety Assessment procedure for two-lane two-way rural roads, namely Human Factors Evaluation procedure, which accounts for the influence of Human Factors in accidents triggering factors. The purpose of such a procedure is to provide an instrument to evaluate the risk of accidents occurrence because of wrong perceptions and expectations caused by the road. This often translates in operational errors, which may become driving errors that finally results in accidents, if uncorrected. The need of a Network-wide Road Safety Assessment procedure which accounts for Human Factors, together with an overview of considered methodologies, is discussed with a focus on Road Safety Inspection procedures. Indeed, visual site inspections and surveys allow to identify specific critical issue that may otherwise be missed while using big data analysis. Moreover, it has been decided that the Human Factors Evaluation procedure must follows the requirements of the updated 2008/96/EU directive (European Parliament and the Council, 2019). This will let it be a usable instrument for road agencies

Human Factors in Road Design: A Review of Italian Design Standards

Human Factors are stable psychological, psychophysical, and physiological limits that influence the performance and safety of technical systems managed by humans. Roads are made for human use, but nowadays not completely on a human scale. Many studies demonstrate that Human Factors are a key factor in accident occurrence and thus it is mandatory to consider them in the definition of design standards. This research provides a methodological approach to reviewing design standards based on Human Factors. The methodology identifies which Human Factors aspects are relevant for each specific design feature. The reviewer is then able to judge if those aspects are considered using checklists. Moreover, the paper presents a review of the Italian design standards using the proposed methodology. This identifies to what extent Human Factors are considered in the Italian design standards, analyzing if they match the requirements of the three rules of Human Factors proposed by PIARC (Permanent International Association of Road Congresses). The results identify where Italian design standards consider Human Factors and where they do not. This is where further improvements should be made so that engineering solutions could match psychological requirements, for safer and ergonomic road infrastructures. The proposed approach provides a structured and systematic procedure for the analysis which has been found to be suitable also for road safety audits procedures

Application and Evaluation of a Non-Accident-Based Approach to Road Safety Analysis Based on Infrastructure-Related Human Factors

Too often the identification of critical road sites is made by “accident-based” methods that consider the occurred accidents’ number. Nevertheless, such a procedure may encounter some difficulties when an agency does not have reliable and complete crash data at the site level (e.g., accidents contributing factors not clear or approximate accident location) or when crashes are underreported. Furthermore, relying on accident data means waiting for them to occur with the related consequences (possible deaths and injuries). A non-accident-based approach has been proposed by PIARC. This approach involves the application of the Human Factors Evaluation Tool (HFET), which is based on the principles of Human Factors (HF). The HFET can be applied to road segments by on-site inspections and provides a numerical performance measure named Human Factors Scores (HFS). This paper analyses which relationship exists between the results of the standard accident-based methods and those obtainable with HFET, based on the analysis of self-explaining and ergonomic features of the infrastructure. The study carried out for this purpose considered 23 km of two-way two-lane roads in Italy. A good correspondence was obtained, meaning that high risky road segments identified by the HFS correspond to road segments already burdened by a high number of accidents. The results demonstrated that the HFET allows for identifying of road segments requiring safety improvements even if accident data are unavailable. It allows for improving a proactive NSS, avoiding waiting for accidents to occur

Assessing the Impact on Road Safety of Automated Vehicles: An Infrastructure Inspection-Based Approach

How safe will Automated Vehicles (AVs) be? It depends on technologies, vehicles, other road users, and infrastructures. The only certainty is that automated vehicles will not solve all road safety issues. As the penetration of AVs might be much more sudden than road infrastructure modification, the infrastructure revision process should start immediately by then, and road authorities must be ready in turn. This paper presents an approach based on road safety inspections to quantify and compare the expected safety levels for a road section with different combinations of Automated and Conventional Vehicles (CVs). Developed in the framework of the EC project CoEXist, the proposed approach allows for identifying the possible safety issues that may arise when introducing AVs. All safety issues are judged in terms of risk, which is the product of the exposure, the likelihood of the crash, and the severity of the possible consequences. All these aspects are analyzed in different scenarios considering different AV penetration levels and driving logic. The results show a potential risk decrease according to the higher penetration of AVs. Nevertheless, the analysis highlights that safety issues may arise with the introduction of specific AVs’ driving logics

D3.3 Tools for assessing the traffic impacts of automated vehicles

A key goal of the CoEXistproject is to enable local road authorities and other urban mobility stakeholders to evaluate the impact of the introduction of connected and automated vehicles (CAVs).One part of achieving this goal is the development of extended traffic models able to model traffic with various mixes of different types of CAVs, as presented in CoEXistdeliverablesD2.10/D2.11and D2.7/D2.8. However,there are large uncertaintiesassociatednot only with the behaviour of the automated vehiclesand the reactions of non-automated road users to the CAVs, but alsotherate of introduction of various types of CAVs into the vehicle fleet. These uncertainties makeinterpreting the output of traffic models significantly harder. The aim of this documentis to present the approach that has been used in CoEXist,that in a structured and sound way can be used by road authorities to assess the traffic impact of automationona given road design, traffic controllers, regulations, etc. The traffic performance and space efficiency assessment approach utilizes outputs from automation-ready transport modelling tools as input. The traffic models are applied to a set of consistent experimentswith respect to penetration rates and differentmixes of AV classes, as described in deliverable D3.1.Relevant performance metrics,presented in deliverable D3.2,are calculatedfrom the model outputs and used to assess the traffic impact of automationin terms of traffic performance for different infrastructure designs.An essential functionality ofthe assessment approach is to consider and visualize effects of the large uncertainties with respect to how different types of AVs might behave and which mixes of different typesof AVs that are likely to CoEXistat different stages of the transition period towards full automation. Assessing traffic safety based on traffic models is difficult and in addition to the traffic performance and space efficiency assessment tool,two different safety assessment tools aredeveloped:one qualitative safety assessment approach,which assess potential safety effects in relation to the accident types and automation functions that are relevant for aninfrastructure design; and one more detailed safety assessment approach based on safetyinspections. These two safety assessment approachesare not relyingon the results of modelling tools and can be used independently

D4.3 Technical report on the application of the tools for assessing traffic impacts of automated vehicles

The many uncertainties related to the introduction of automated vehiclesimply a need to for a structured way ofassessing impacts for different future development with respect to penetration rates of automated vehiclesand mixes of different types of automated vehicles but also for different travel demand levels and behavioural changes of road users. In order to provide a summarized picture of potential impacts for different stages of coexistence between automated vehicles and other road usersan assessment approach was developed (see D3.3 (Pereira et al., 2020)for details). To simplify the assessment and to create a standard way of presenting the results taking uncertainties into account the approach was implemented inone spreadsheet-based toolfor assessment of trafficperformance and space efficiency andone tool for qualitative safety assessment. The aim of this report is to present the results from applying the tools for assessing traffic impacts of automated vehicles to the simulation outputsofthe eight use cases within CoEXist.The aim of thetraffic performance and space efficiencytool is to concisely present an assessment of the traffic performance impact ofthe introduction of automated vehicles, based on the output from models, including the uncertainties considered.The aim of the qualitative safety assessment tool is toprovide rough estimates on how automated driving functionsmight affect safety for use case relevant accident types. Both of these tools are tested and demonstrated through the applications presented here