Abstracts for the third Annual Scientific Seminar of the NTSA
Theories and research methods in Road Traffic Safety Science
To be held at Institute of Transport Economics (TØI) in Oslo, Norway May 6-7 2014
The use of randomized controlled trials in traffic safety - two Danish
examples
by Harry Lahrmann, Traffic Research Group, Department of Development and Planning, Aalborg
University
Although randomized trials are the gold standard for a trial it is used only rarely in studies of traffic
safety effects. Probably because the common belief is that they require extensive resources to
implement. Modern ICT technology, however, gives a number of options for implementing
randomized controlled trials (RCT) which have not been possible previously and which drastically
reduces the cost of carrying out such experiments. In this submission, I will present two RCT’s
conducted by TRG and I will give focus on how ICT has been used both to ensure valid results, and
reduce costs in the experiments. One study examined the effect of lights on bikes and the second
effect of a brightly colored cycling jacket. Finally, I will be discussed how a high use of ICT could
increase the use of RCT in road safety work.
1
Towards a general theory of the relationship between exposure and risk
Abstract to Scientific Seminar of the Nordic Traffic Safety Academy, Oslo, May 67, 2014
Rune Elvik, Institute of Transport Economics, Gaustadalléen 21, NO-0349, Oslo, Norway
A considerable amount of research indicates that there is a negative relationship between exposure
and risk. The greater the exposure, the lower the risk. This relationship suggests that as exposure
grows, road users learn how to identify risks and successfully control them. This paper proposes as
a general hypothesis that in the case of perfect learning risk is the inverse of exposure. When risk
becomes the inverse of exposure, risk factors will no longer produce any systematic variation in the
number of accidents. This is implied by the shape of the inverse function. It is a paradox of risk
theory that risk factors that are associated with an increased probability of accident occurrence do
not generate systematic variation in the number of accidents. Factors that may cause a different
shape of the relationship between exposure and risk than the inverse function are discussed. There
are two groups of factors: problems in measuring exposure correctly and road user behavioural
adaptation to risk factors. An incorrect measurement of exposure can both generate a fictitious
inverse relationship and hide a true inverse relationship. The estimator used for exposure should,
ideally speaking, reflect the number of opportunities for accidents to occur; a variable for which no
perfect operational definition exists today. Road user behavioural adaptation to risk factors may also
influence the shape of the relationship between exposure and risk.
2
The accident risk of foreign and Norwegian hauliers on Norwegian roads
Tor-Olav Nævestad, Torkel Bjørnskau, Inger Beate Hovi, Elise Caspersen & Ross O. Phillips,
Institute of Transport Economics
Abstract
Global and European market pressures have led to an ongoing increase in the shares of foreign
actors in the Norwegian transport sector. Today, the number of foreign actors involved in domestic
road transport of goods in Norway (cabotage) is profoundly limited by Norwegian regulations,
which is in accordance with current EU-Regulation on cabotage (EC 1072/2009). However, as part
of the accomplishment of the common market, the European Commission has pushed for a removal
of market barriers to for example allow cabotage. Given the low level of wages in recent EU
member countries, it is likely that a possible lift of cabotage restrictions will increase the share of
Eastern European lorries in Norway. There are, however, no systematic studies comparing the
accident risk of Norwegian hauliers and foreign hauliers on Norwegian roads, and data from the
National Public Roads Administration and the police indicate that foreign actors, especially from
Eastern Europe, are overrepresented in accidents
The main aims are to compare the accident risk of Norwegian and foreign actors transporting goods
on Norwegian roads, and to discuss the results in light of accident risk factors. The accident risk of
hauliers on Norwegian roads is estimated based on exposure data from the national lorry surveys,
which have been conducted continuously by Statistics Norway since 1993, and similar surveys
conducted in each of EU’s member state, according to the Eurostat’s statistics directive. These data
are combined with accident data from the National Road Databank, which include data on the
nationality of the vehicles involved in accidents. The results are discussed in light of a literature
review, which suggests at least four potential risk factors representing unique traffic safety
challenges of foreign hauliers on Norwegian roads: 1) safety culture, 2) competence and training 3)
technology and equipment and 4) framework conditions.
3
Matus Sucha
Katedra psychologie FF /
Univerzita Palackého v Olomouci
Drivers and pedestrians interaction at zebra crossings
Aim of the proposed paper is to present study design, research methodology and continuous outcomes
of the mentioned study.
Aim of this study is to describe pedestrians and drivers interaction and behaviour in the situations of
their encounters at zebra crossing in urban area. Furthermore, to identify factors (accounting
pedestrians and drivers behaviour, environment), which can predict accidents.
Study design
1. Exploration of pedestrians and driver needs and conflict situations (identification of problem)
– focus groups with pedestrians and drivers (separately).
2. Observation spots – 4 zebra crossing within Olomouc city, 2 zebra crossings within city centre
(with high volumes of car and pedestrians), 2 zebra crossings outside of city centre.
3. Observation time – Morning and evening (rush ours), noon (low densities), together 4 hours/
day. 5 days of observations.
4. Observation and interviews:
a. On site observation: 3 observers at the same time at the same place: 1st observer
observes driver, 2nd observes pedestrian, 3rd conduct interview with pedestrian (after
crossing the road).
b. Data from cameras – 24 hours recordings of the selected spots.
5. Measurements:
a. Car speed – at selected spots.
b. Volumes – cars and pedestrians.
6. Exploration – to better understand results:
a. Drivers and pedestrians focus groups.
b. Expert workshops.
Data collection is planed for January/ February 2014 (conditions without snow and ice are needed
though). At the meeting I plan to present design of the study and preliminary results which should be
by then available.
4
How to make intelligible the differences between countries in road safety by developing
road risk regulation regimes by means of a constructivist approach of complexity?
Sylvain Lassarre
GRETIA-INRETS, Champs sur Marne, France
Robert Delorme
Université de Versailles Saint-Quentin, France
The quantitative analysis of international data collected by IRTAD on road accidents shows gaps in
term of road risk, by example between France and UK with
a ratio of mortality risk per
vehicle*kilometre equal to two over more than 50 years . There is some irreducibility in this gap
which can partially be explained by differences in exposure to some risk factors such as speed or
alcohol and driving, and cannot be reduced by evaluation of performances of a priori models on road
safety management such as the one provided by the World Bank GRSF. We recommend a
constructivist framework mixing quantitative models and qualitative approaches lead by a
pluridisciplinary team of researchers and guided by a three levels recursive scheme : road safety
action, action model, and meta-model to control a satisficing criteria of intelligibility of the gap. The
road risk regulation regimes emerge from this construct as stable forms of governance and
organization of road safety endowed with identifiable characteristics, such as the PIE factor :
professionalization, integration and evaluation, on which the gap are manifested.
Two results stand out. First, two contrasted R4s are characterised, a distributed British R4 and a
French R4 mainly under a central government and administrative influence. Second, a group of three
factors appears especially significant. They are the professionalization of the actors, and the
integration, and the evaluation of road safety action. They are interdependent and behave as a global
factor, the “PIE factor”.
By regulation, we mean the processes which lower the fluctuations or the deviations from a goal (in
that case to reduce the deviation from the target in terms of the number of fatalities). The governance
is seen as a set of manners according to which the actors and public institutions manage their common
affairs. In some specific domain, the governance can be shared between actors and institutions,
without any dominance from one of them by power or legal capacity. It can also not be shared and be
under the dominance of a specific sector. It is a question of degrees. Following this concept, we
suggest to define the British regime as a distributed governance and the French regime a governance
dominated by central government and administration.
From
the
international
comparison,
three
factors
appears
especially
discriminating:
professionalisation (P), integration (I) and evaluation (E). They are interdependent and form a
configuration which is identified as the PIE factor. A low coherence could last because none of the
three terms put pressure on the raising of the others. For the high coherence, it is the opposite. A large
and sustainable evaluation process requires a professionalisation having similar qualities and a
common language (risk indicators), as a transparent and complete information, all in favour of
departitioning and integration.
5
Deepak Kaphle BEng MScEng MCIHT
New Roads and Street Works Engineer – Greenwich Council
Traffic and Safety Researcher – DK Consulting
Extent of Introduction of Speed Reducing Physical Features in
the UK Roads: Growing Annoyance and Frustration amongst
Road Users and Residents
Named inappropriately as ‘Traffic Calming Measures’ instead of ‘Speed Reducing Features’ a
number of Regulations have been passed from the UK Parliament and are currently in force to allow
the UK Local Authorities to introduce ‘Speed Reducing Features’ on their network. A number of
guidelines and manuals have been published highlighting mainly the positive side. As a result,
introduction of such features are in priority list in every UK Local Authorities and a significant
proportion of road safety budget are spent on consultation, design and construction involving these
engineering features. The extent of introduction of such traditional features currently seems to ignore
the fact of growing annoyance and frustrations amongst road users and local residents. Clearly,
psychological aspect or impression as a result of these features is being ignored. There is a question
mark on how the introduction of these features is presented during consultation process and how they
are represented in decision making process even residents object them.
Not only limited to the annoyance and frustrations amongst road users and local residents, speed
reducing features add further on street clutter, damage vehicles and impose difficulty in on street
parking practices. These features obviously increase in response time of emergency services. Little
are known or highlighted on the environmental impacts because of these features. Introduction of
such features to this extent will eventually leave technological improvements behind and behavioural
changes will take long to happen due to growing annoyance and frustrations.
Concept of shared space has well penetrated but is little highlighted due to fear. Many Local
Authorities find such scheme’s implementation and maintenance very expensive. Some Authorities
are drawn back just because they are not sure about whether it would work or would not afford a risk.
This presentation will highlight the hidden issues behind the current practices. It will come up with
alternative views and suggest some technological improvements to minimise over-use of
conventional speed reducing features.
6
Comparison of severity assessments based on Czech and Swedish traffic conflict techniques
Jiří Ambros1, Aliaksei Laureshyn2
1
Centrum dopravního výzkumu, v.v.i., Líšeňská 33a, 63600 Brno, Czech Republic,
jiri.ambros@cdv.cz
2
Lund University, Department of Technology and Society, Faculty of Engineering, Box 118, 22100
Lund, Sweden, aliaksei.laureshyn@tft.lth.se
Traffic conflict technique (TCT) is a method for the systematic observation of conflicting traffic
behaviour. Various TCTs have been developed around the world in order to be able to collect
intermediate data for road safety analyses, study driving behaviour, etc. Conflict severity assessment
is the focus of the paper.
Various observed, measured or calculated parameters are used in TCTs. The Swedish TCT uses time
and distance estimates, the Czech TCT assesses subjectively the severity of evasive manoeuvre. The
latter may likely be more susceptible to subjective biases than the former technique, which has been
deemed the most mature. In order to test the applicability of the Czech TCT, its comparison with
Swedish one is wanting.
In order to fill this gap, short video footages of traffic conflicts were used. The severity of recorded
conflicts was assessed with both Swedish and Czech TCTs. The results of comparison are presented
and discussed, together with the practical implications.
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Theories and research methods in Road Traffic Safety Science
Daniel Bell (FACTUM Chaloupka & Risser OG)
"Assessing vulnerable road user needs in view of emerging ITS technologies"
Technological innovations in the transport sector, specifically in the fields of Intelligent Transport
System (ITS) solutions, have mainly been focussing on car drivers and their respective safety and
mobility needs. Recent ITS research activities aimed at vulnerable road users (VRUs) has increased,
focussing on the development of solutions that improve safety, mobility and comfort of pedestrians,
cyclists and powered two-wheelers.
Based on the international projects VRUITS (vulnerable road users and ITS), CONSOL (CONcerns and
SOLutions – Road safety in the ageing societies) and the national projects TrafficCheck.at (Urban sensing
platform to improve traffic lights), TellMeTheWay (Multi-modal routing in urban transport systems),
Ways2Navigate (Pedestrian navigation), mobility needs and issues of different VRU groups are
discussed in view of the technology potential of current ITS solutions. Specific focus will be on the the
heterogeneity of the different VRU groups, discussing individual characteristics such as gender, age and health,
and their respective needs in view of traffic safety, general mobility and comfort aspects.
Methodologies for user needs assessment that are discussed and that were applied within the different projects
range from qualitative approaches such as focus group discussions, expert interviews, best practice analysis to
quantitative approaches like field trial evaluations. Combining qualitative and quantitative methods allow for a
multi-level approach investigating the different dimensions of VRU mobility.
Consequently, current developments in ITS technologies are discussed in regards to their potential to increase
traffic safety, general mobility and inclusiveness in modern transport systems for different road user groups.
8
The effects of speed cameras and section control on crashes – a meta-analysis
Alena Høye
Institute of Transport Economics – TØI
Gaustadalléen 21, NO 0349, Oslo, Norway
Phone: +47 4889 8074 E-mail: alh@toi.no
ABSTRACT
A meta-analysis has been conducted of the safety effects of speed cameras and section control in order
to estimate the size of the effect on crashes and the length of road downstream of camera locations
where crashes are affected.
Results from 14 empirical studies of the effects of speed cameras on crashes and 4 empirical studies of
the effects of section control on crashes were summarized by means of the log odds method of metaanalysis. Additionally, 14 studies of the effects of speed cameras and section control on speed were
included in the study.
Speed cameras were found to reduce injury crashes by up to 18% at camera sites and fatal crashes by
22% on longer road sections downstream of the camera location. Section control was found to reduce
injury crashes by 30% and fatal and serious injury crashes by 56%. A sensitivity analysis does not
indicate that results are likely to be affected by publication bias or whether or not regression to the
mean is controlled for.
Speed cameras and section control were found to reduce speed by 11% on average at speed camera
locations and on roads with section control. The crash effects are somewhat greater than one would
expect based on the effects on speed and the speed-crash relationship as described by the power model.
Thus, there may be other changes of driver behavior than speed reductions that contribute to reducing
crashes.
The effect of speed cameras on speed and crashes becomes weaker on the first two kilometers
downstream of camera locations and is about zero 2 km downstream of the speed camera, unless there
are more speed cameras on the same road. Despite some braking and accelerating in the immediate
vicinity of the speed cameras, no increases of speed or crashes were found downstream of camera
locations.
9
Is it reliable that speed-calming solutions as ISA can reach the drivers, who
needed it most?
by Niels Agerholm, Traffic Research Group, Department of Civil Engineering, Aalborg University
A significant number of trials with Intelligent Speed Adaptation (ISA) have been carried out within
the last two decades. Almost all with a promising result; the drivers reduce their proportion of
speeding and are in general positive to ISA. However, two tings question this offhand success story;
1: there has been no commercial break through for ISA so far, even though estimated has shown
that ISA can reduce the n. of fatalities in traffic accidents with up to 59%, and 2: in the only ISA
trial included drivers, who not participated voluntary in the trial, ISA had virtually no effect on
these drivers. The ISA trial with involuntary participants was known as ISA C and was carried out
in and around the Danish town Vejle 2007-2008. First an ultra short presentation to ISA will be
given. It will be followed by a project presentation of ISA C followed with the most significant
results regarding the involuntary drivers and other circumstances, which can have resulted in the
limited effect from ISA in the trial. Finally, there will be presented some considerations about ISA
and involuntary drivers in general – are there national differences and has the attitude changed in
the last year to a more safety-oriented view in the public?
10
The influence of motorcyclists’ behavioral and road environment factors on
the occurrence of traffic conflicts at access points on Malaysian primary roads
Muhammad Marizwan bin Abdul Manan
Lund University
To investigate the effects of motorcyclists’ behavior and road environment attributes on the
occurrence of serious traffic conflicts involving motorcyclists entering primary roads, data from an
observational study, conducted at access points of straight sections of primary roads in Malaysia
was used. In order to handle the unobserved heterogeneity in small sample data size, this study
applied the mixed effects logistic regression with multilevel bootstrapping. Two statistically
significant models were produced, which have 2 levels of random effect parameters, i.e.
motorcyclists’ attributes and behavior at Level 1 and road environment attributes as Level 2.
Among all the road environment attributes tested, the traffic volume and the speed limit was found
statistically significant and only contributed to 26% to 29% of the variations in affecting the traffic
conflict outcome which implies that 71 to 74% of unmeasured or un-described attributes and
behavior of motorcyclists still have an importance in predicting the outcome: a serious traffic
conflict. As for the fixed effect parameters, both models have shown that the risk of motorcyclists
being involved in a serious traffic conflict is 2 to 4 times more likely if they accept a shorter gap
with a single approaching vehicle (time lag < 4 seconds) and in between two vehicles (time gap < 4
seconds). A road environment factor, such as narrow lane (seen in Model A) and a behavior factor,
such as stopping at the stop line (seen in Model B) also influence the occurrence of a serious traffic
conflict compared to those entering into a wider lane road and without stopping at the stop line
respectively.
11