Distributions conditioned on extrapolated events via copula and extreme value theory.

In an interaction between road users, the proximity and speed are two interdependent dimensions which can be captured by a type of multivariate distribution called Copula. Copula requires all marginal distribution functions to be known. However, finding the marginal distribution of the proximity dimension is challenging, as its histogram usually contains several peaks.

Speed-securing measures on rural roads in Sweden: An observational study.

Objective: Speed-securing measures are intended to, as the name suggests, to secure that the speeds of road users do not exceed the safe speed for a given type of environment. The purpose of this study was to make an evaluation of existing speed-securing measures on rural roads in Sweden to see how well they manage to limit the speed.

Methods And Data: A total of 34 unique locations have been filmed with drones with varying speed limits between 40 and 70 km/h.

Injury severity prediction of cyclist crashes using random forests and random parameters logit models.

Cycling provides numerous benefits to individuals and to society but the burden of road traffic injuries and fatalities is disproportionately sustained by cyclists. Without awareness of the contributory factors of cyclist death and injury, the capability to implement context-specific and appropriate measures is severely limited. In this paper, we investigated the effects of the characteristics related to the road, the environment, the vehicle involved, the driver, and the cyclist on severity of crashes involving cyclists analysing 72,363 crashes that occurred in Great Britain in the period 2016-2018.

A driving simulator study to evaluate the effects of different types of median separation on driving behavior on 2 + 1 roads.

In recent years, several countries have started to introduce 2 + 1 roads into their road networks. Although some studies have recognized the great benefits of using 2 + 1 roads, few studies have investigated the effects of different design features of 2 + 1 roads on driver behavior and driving performance, including the type of median separation between opposing traffic flows. The overall aim of this driving simulator study is to determine whether different types of median separation on 2 + 1 roads affect driving behavior, and to provide new insights for designing more effective and safer 2 + 1 roads.

Crash modification functions for pavement surface condition and geometric design indicators.

The combined contribution to highway safety of pavement surface and geometric design indicators is not well investigated due to the complexity of data collection and high time variability of pavement surface conditions. Introduction of high efficiency equipment for comprehensive road surveys is mitigating this issue, expanding possibilities of data integration. In this framework, the present study developed crash modification functions (CMFs) of pavement surface and geometric design indicators for different crash types (total, run-off-the-road, and others), pavement conditions (dry and wet), and lighting conditions (daytime and nighttime) based on data from two-lane rural highways in Italy.

Impact on Road Safety and Operation of Rerouting Traffic in Rural Travel Time Information System.

The Travel Time Information System (TTIS) is an Intelligent Traffic Control System installed in Poland. As is common, travel time is the only factor in the decision about rerouting traffic, while a route recommendation may consider multiple criteria, including road safety. The aim of the paper is to analyze the safety level of the entire road network when traffic is rerouted on paths with different road categories, intersection types, road environments, and densities of access points.

Comparison of Bayesian techniques for the before-after evaluation of the safety effectiveness of short 2+1 road sections.

In evaluating the effectiveness of a road safety treatment, the regression to the mean phenomenon is a cause for concern because of a possible overestimation of benefits. Therefore, Bayesian approaches are usually suggested as the most appropriate methodologies for before-after studies as they account for regression to the mean effects. The empirical Bayes (EB) methodology examines the estimation of the expected number of crashes that would have occurred without treatment and compares them with the crashes observed at the treated sites.

Safety assessment of passing relief lanes using microsimulation-based conflicts analysis.

The paper target is to analyze the influence of passing lane section and merging area lengths, which represent a critical part in the geometric design of passing lanes. The lack of observed data and the still limited implementation of short passing 2+1 lane in Poland do not allow to perform a reliable performance-based design of their length to balance context and economical restrains with operational and safety performances. Besides, defining the optimum geometric design from observed data is a reactive approach which require detailed observations and evaluations of the safety and operational performances for different geometric configurations.

Investigating the influence on safety of retrofitting Italian motorways with barriers meeting a new EU standard.

Objective: A new European Union (EU) regulation for safety barriers, which is based on performance, has encouraged road agencies to perform an upgrade of old barriers, with the expectation that there will be safety benefits at the retrofitted sites. The new class of barriers was designed and installed in compliance with the 1998 (European Norm) EN 1317 standards for road restraint systems, which lays down common requirements for the testing and certification of road restraint systems in all countries of the European Committee for Standardization (CEN). Both the older and new barriers are made of steel and are installed in such a way as to avoid vehicle intrusion, but the older ones are thought to be only effective at low speeds and large angles of impact.

Assessing the stochastic variability of the Benefit-Cost ratio in roadway safety management.

Road Agencies set quantitative targets and adopt related road safety strategies within the priorities and the available resources at the time of an economic crisis. In this framework, benefit-cost analyses (BCA) are carried out to support the decision making process and alternative measures are ranked according to their expected benefit and benefit-cost ratio calculated using a Safety Performance Function (SPF) and Crash Modification Factors (CMFs) as predictors of future safety performances. Due to the variance of CMFs and crash frequency we are uncertain what the benefits of some future actions will be.