Zoi Christoforou

Effects of alcohol on speeding and road positioning of young drivers: Driving simulator study

Young people who drink and drive have a relatively higher risk of crash involvement for all breath alcohol concentration (BrAC) ranges. However, not all aspects of the effect of alcohol consumption on the behavior of young drivers have been sufficiently addressed—especially the differentiated effect of alcohol on their driving performance. The behavior of young drivers under the influence of alcohol is explored within this research in a driving simulator experiment in which participants were subjected to a common predefined dose of alcohol consumption. Comparing behavior before and after consumption as well as across individuals and different BrAC levels allows for useful insights into driver behavior, as well as for suggestions on policy interventions. Results indicate strong differences in individuals, mainly because of differentiated driving experience and baseline driving skills. The results also designate reaction time and speeding as the most robust alcohol impairment indicators that affect driver choices directly. Most important, results suggest that the BrAC–speed curve across individuals is not monotonic over all BrAC intervals.

Influencing Longitudinal Passenger Distribution on Railway Platforms to Shorten and Regularize Train Dwell Times

The longitudinal distribution of passengers waiting on a train platform influences the boarding and alighting time. A smoother, more uniform distribution could benefit both traffic operations and passenger experiences. This paper investigates pedestrian traffic performance and the train operations that it influences in an integrated way by proposing (a) two in situ solutions to inform passengers and influence their waiting position on the platform, (b) a specific survey of passenger behavior under these conditions, (c) a modeling scheme based on a pedestrian microsimulation, and (d) an example of application to a suburban rail station in eastern Paris, the Noisy–Champs Station on the Réseau Express Régional (RER) A Line. The example reveals a traffic phenomenon of corridor–car interplay that implicates the specific behavior of late passengers and the contribution of this phenomenon to train dwell time.

Managing planned disruptions of mass transit systems

Unplanned disruptions of rail transit networks have been studied extensively. Planned disruptions for works essentially are different mainly because of their longer duration, which allows passengers to build alternative route choice strategies. The literature on this topic remains scarce. In this study, a novel methodology was proposed to enable operators to evaluate different disruption management schemes and to obtain explicit estimations of travel times, passenger comfort flows, and levels of service. Statistical tools were used to evaluate the different strategies. The methodology is illustrated here through a large-scale application to a real line disruption in Paris. The disruption took place in July 2015 as the result of network maintenance work and affected Line A of Réseau Express Régional, a major suburban railway line that provides more than 1 million trips on a typical working day. Study results indicated that the disruption would have significantly increased the generalized cost (GC) of passengers if no action had been taken. The operator’s disruption management scheme included bus bridging and increases in service frequency on alternative routes. Evaluation showed that this plan restored the average GC across the whole network. Passengers who initially used the disrupted line experienced increased GC when they used the longer, alternative routes. Passengers who initially used those alternative routes experienced lower GC as a result of the increase in service frequency. Finally, capacity problems were observed on the buses that ensured a bridge across the disrupted link.

A Priori Evaluation of Policy Measures Against Alcohol-Impaired Driving: French Case Study

On one hand, drinking and driving is an ever-growing concern for decision makers. On the other hand, stated preference (SP) surveys have rarely been used to assess the effectiveness of legislative road safety measures. The objective of this paper was to explore the potential impact of an intended safety measure on the behavior of French drivers. In particular, this study investigated the obligation of all drivers always to keep in their vehicles an individual one-use breath alcohol test device. For this purpose, an SP survey was designed and undertaken to elicit individuals’ preferences. Ordered probit models were specified on the responses of 240 young drinkers and drivers in the Paris region. Results indicate two factors as being the most influential: (a) unemployment and (b) believing that the new legislation is proposed on public revenue grounds. In particular, both factors cause individuals to reject the legislation, which therefore has a trivial impact on their stated behavior. Targeted communication campaigns should be designed to grow awareness and convince drivers of the beneficial road safety outcomes.

A transit bottleneck model for waiting passengers and its implications for traffic assignment

The paper addresses the issue of passenger waiting at a station platform, from which they plan to board transit services towards egress stations. Each transit service has a specific set of downstream egress stations and is operated at given frequency using homogeneous vehicles of limited available capacity. We propose a static model that yields “passenger stocks” on the platform and individual waiting times by egress station, as well as the assignment of vehicle capacity to the flows by egress station. Two cases are considered; unsaturated versus saturated. The unsaturated case is addressed by standard line combination, where service frequency is added up among the routes that serve a given egress station. The saturated case is addressed by making explicit the average number of passengers waiting on platform for a given egress station. From these passenger stocks, we deduce the individual probability to board a vehicle of limited capacity that serves a given route (hence a given subset of egress stations). Waiting passengers are assumed to be mingling on the origin platform. The subset of routes that serve a given egress station, their vehicle capacities along with the associated boarding probabilities give a line capacity by destination. The bottleneck model confronts this capacity to demand during the assignment period and provides both the stock of waiting passengers and an average waiting time per passenger. The vector of passenger stocks by egress station is shown to satisfy a fixed point problem. The existence of a solution is demonstrated.