Andras Varhelyi

The effects of in-car speed limiters – Field studies

Field trials in three European countries, the Netherlands, Spain and Sweden were carried out in order to investigate the effects of an in-car speed limiter. The trials were carried out on urban and rural roads including motorways. A so-called unobtrusive instrumented car was used, where all the measuring equipment was hidden. All the speed limit categories in the respective countries, ranging from 30 km/h to 120 km/h were included. The results showed that the effects of the limiter were greatest in free driving conditions outside platoons. How-ever, the limiter also had effects in congested traffic. Momentary high speeds were suppressed effectively, which resulted in less variation of speeds. Approach speeds at roundabouts, inter-sections and curves became smoother, car-following behaviour became safer in the speed range of 30 km/h to 50 km/h. On the other hand, in the speed range of 70 km/h to 90 km/h a slightly higher number of short time-gaps suggested less safe car-following behaviour. Other negative behavioural effects were slightly increased travel time and the increased frustration and stress for the drivers caused by the limiter. The majority of the subjects accepted the speed limiter as a driver-operated system. Half of the drivers would accept the limiter volun-tarily in their cars. (Less)

The effects of small roundabouts on emissions and fuel consumption: a case study

The effects of small roundabouts on emissions and fuel consumption were evaluated using the “car-following” method in a before/after study. The results showed that at a roundabout replacing a signalised junction, CO emissions decreased by 29%, NOx emissions by 21%, and fuel consumption by 28%. At roundabouts, replacing yield regulated junctions, CO emissions increased on average by 4%, NOx emissions by 6%, and fuel consumption by 3%. The results indicate that the large reductions in emissions and fuel consumption at one rebuilt signalised junction can “compensate for” the increase produced by several yield-regulated junctions rebuilt as roundabouts.

Development of a method for detecting jerks in safety critical events

A new method for detecting jerks in safety critical events, based on the characteristics of the braking caused by the driver in time critical situations, has been developed and evaluated in a small pilot test and also applied on a naturalistic driving study. A portable event data recorder, capable of measuring and recording acceleration profiles for a predetermined time period before and after the safety critical situation, has also been developed to ensure high data quality used to evaluate the proposed method. Thus, an analysis of the acceleration profile is possible during the entire braking event. The study involves analyses of acceleration profiles and different characteristics of the rate of change of the acceleration profiles, i.e. jerks, such as negative jerk, used in previous studies, and a peak-to-peak value of the jerk. The finding is that the proposed method provides a more distinct difference between critical and potentially critical events and thus may be an appropriate method used to detect safety critical events.

Relative fatality risk curve to describe the effect of change in the impact speed on fatality risk of pedestrians struck by a motor vehicle.

Models describing the relation between impact speed and fatality risk for pedestrians struck by a motor vehicle have frequently been used by practitioners and scientists in applying an S curve to visualize the importance of speed for the chance of survival. Recent studies have suggested that these risk curves are biased and do not give representative risk values. These studies present new fatality risk curves that show much lower risks of fatality than before, which has caused confusion and misconceptions about how these new curves should be interpreted, and how this should affect speed management policy. The aim here is to deepen the understanding of the implications this new knowledge has for urban speed policies by analyzing (1) what the most reliable knowledge is for this relation today and what limitations it has, (2) how these risk curves are interpreted today, and what limitations this interpretation has and (3) what the risk curves say about the importance of speed and speed changes. This paper proposes an additional tool, the relative fatality risk curve, to help prevent misconceptions. The proposed relative risk ratios and curves show that, even though the most recent results indicate that the risk is lower than assumed by the older models, the fatality risk is still as sensitive to speed changes as before.

Test of HMI Alternatives for Driver Support to Keep Safe Speed and Safe Distance - A Simulator Study

This paper describes a driving simulator trial to evaluate driver reactions to a number of alternative information/ warning modes of a multi-modal system for the “safe speed and safe distance” concept. In 2006, eight Human Machine Interaction alternatives, consisting of a combination of visual, haptic and auditory modes were used alternatively to give information/warning to the driver on safe speed, safe distance and the prevailing speed limit. Thirty-four test drivers drove once without the SASPENCE system and twice with the system. The system did not affect the speed behaviour of the driver in either normal conditions or sharp curves. The average number of alarms was slightly larger when driving with the system. The haptic HMI alternative - the combination of force feedback in the accelerator pedal and vibration of the seat belt for speed warning and pulsation in the accelerator pedal for distance warning - gave the lowest proportion of time of being in an unsafe situation, and improved driver-reaction time most. This haptic alternative also resulted in the most positive driver ratings/experiences of the system. The visual alternatives used were positively rated by the drivers, but no clear differences between them could be found according to opinions. The auditory feedback was not appreciated by the drivers. All the drivers stated they would accept the SASPENCE system if the system was installed in their cars free of charge. The majority would accept a system that was both informative and advisory, while some of them also stated they would accept an intervening system. (Less)

DYNAMIC SPEED ADAPTATION IN ADVERSE CONDITIONS │ A System Proposal │

This paper proposes a system for dynamic speed adaptation in adverse conditions, such as wet/slippery roads, decreased visibility, darkness and sharp curves. Accident risks increase drastically in such conditions, especially since drivers often do not adapt speeds to lower friction or impaired visibility. Thus, the discussion is centred around a method for calculating the appropriate highest speeds and a system to influence driver’s speed-choice in these conditions via an in-vehicle device. The safety effect of the proposed system is estimated to result in a 19% - 42% reduction of injury accidents in Sweden. The paper concludes by making suggestions for further research into alternative technological solutions, effects on driver behaviour and workload and implementation of the system for other reasons than weather and road-dependent adverse conditions. (Less)

Policy instruments for managing road safety on EU-roads

Abstract Directive 2008/96/EC on road infrastructure safety management requires the establishment and implementation of procedures relating to road safety impact assessments (RSIA), road safety audits (RSA), ranking of high accident concentration sections and network safety ranking (NSR) and road safety inspections (RSI). The aim of this article is to present the outputs of BALTRIS project. The goal of the international project BALTRIS is to elaborate the road and street infrastructure safety management procedures and teaching material consistently explaining the above mentioned infrastructure management procedures. Four Baltic Sea region countries (Sweden, Estonia, Latvia, and Lithuania), represented by universities and national road administrations participate in the elaboration of these procedures and teaching material. This article describes the scope of NSR, RSA and RSI procedures prepared in the frame of BALTRIS project, also article provides detailed implementation and execution of procedures for t...

Matching of police and hospital road crash casualty records – a data-linkage study in Malaysia

ABSTRACT Underreporting of road crashes hampers the development of appropriate road safety countermeasures in many countries. In this study, police and hospital records from road crash casualties in the Melaka Tengah district in Malaysia from 2014 were collected to determine their matching and reporting rates. Based on authentic personal identifiers from both types of records, Microsoft SQL was used to reveal how the matching rate varies due to multiple factors. The results showed that 311 cases (of 7625 hospital records) could be linked to both databases, yielding a 4.1% matching rate and a 4.7% police reporting rate. Both the reporting and matching rates increased with the level of injury severity. The significant underreporting in the police database showed that complementary data are necessary for enhancing the current official crash data records.

Road Safety Management – The need for a systematic approach

In order to achieve significant improvements in road safety at the national level, there is a need for a systematic approach to road safety management with clear responsibilities and accountability. In this paper – after a review of the literature on guidelines, recommendations and research findings – twelve essential elements of such a systematic approach are pointed out, and corresponding relevant issues are discussed. These elements are: 1) Define the burden and nature of road casualties; 2) Gain commitment and support from decision makers; 3) Establish road safety policy; 4) Define institutional roles and responsibilities; 5) Identify road safety problems; 6) Set road safety targets; 7) Formulate a strategy and action plan; 8) Allocate responsibility for measures; 9) Ensure funding; 10) Apply measures with known effectiveness; 11) Monitor performance; and 12) Stimulate research and capacity building. The main conclusions are that: a) Monetary values of statistical life have to be established; b) The police register of accidents should be combined with the hospital register; c) Exposure data for all types of road users is necessary; d) The three-dimensional analysis of road safety problems should be employed; e) Safety performance indicators should be used; f) Only countermeasures with known effectiveness should be applied; g) Performance of countermeasures should be monitored on a yearly basis; and h) Commitment from decision makers is decisive!. (Less)

Development of a tool to assess urban transport sustainability: The case of Swedish cities

ABSTRACT This article presents a framework and a tool to assess transport sustainability in Swedish cities that was developed for and together with some cities in Sweden in strong cooperation with the researchers. The tool, called the Transport Sustainability Barometer (TSB), includes a set of hierarchical indicators to measure sustainability in respect to efficiency, accessibility, safety, liveability, emissions, and resource use. The novelty of the TSB is that it proposes the use of both objectively and subjectively measurable indicators, i.e., how the population perceives sustainability of transport, their satisfaction with the transport system, and its effects on the economy, the environment, and social issues. This article also presents the application of the tool in a city in Sweden.