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DOI: 10.1002/cl2.1367
EVIDENCE AND GAP MAP
Social welfare
Effectiveness of road safety interventions: An evidence
and gap map
Rahul Goel
1
|Geetam Tiwari
1
|Mathew Varghese
2
|Kavi Bhalla
3
|
Girish Agrawal
1
|Guneet Saini
4
|Abhaya Jha
1
|Denny John
5
|Ashrita Saran
6
|
Howard White
6
|Dinesh Mohan
1
1
Transportation Research and Injury
Prevention Centre, Indian Institute of
Technology Delhi, New Delhi, India
2
St. Stephen's Hospital, Orthopaedic, Delhi,
India
3
Department of Public Health Sciences,
University of Chicago, Chicago, Illinois, USA
4
Texas A & M University, College Station,
Texas, USA
5
Faculty of Life and Allied Health Sciences,
M S Ramaiah University of Applied Sciences,
Bangalore, Karnataka, India
6
Campbell Collaboration, New Delhi, India
Correspondence
Rahul Goel, Transportation Research and
Injury Prevention Centre, Indian Institute of
Technology Delhi, MS 815, Main Building, IIT
Delhi, Hauz Khas, New Delhi 110016, India.
Email: rgoel@iitd.ac.in
Abstract
Background: Road Traffic injuries (RTI) are among the top ten leading causes of
death in the world resulting in 1.35 million deaths every year, about 93% of which
occur in low‐and middle‐income countries (LMICs). Despite several global
resolutions to reduce traffic injuries, they have continued to grow in many countries.
Many high‐income countries have successfully reduced RTI by using a public health
approach and implementing evidence‐based interventions. As many LMICs develop
their highway infrastructure, adopting a similar scientific approach towards road
safety is crucial. The evidence also needs to be evaluated to assess external validity
because measures that have worked in high‐income countries may not translate
equally well to other contexts. An evidence gap map for RTI is the first step towards
understanding what evidence is available, from where, and the key gaps in
knowledge.
Objectives: The objective of this evidence gap map (EGM) is to identify existing
evidence from all effectiveness studies and systematic reviews related to road safety
interventions. In addition, the EGM identifies gaps in evidence where new primary
studies and systematic reviews could add value. This will help direct future research
and discussions based on systematic evidence towards the approaches and
interventions which are most effective in the road safety sector. This could enable
the generation of evidence for informing policy at global, regional or national levels.
Search Methods: The EGM includes systematic reviews and impact evaluations
assessing the effect of interventions for RTI reported in academic databases,
organization websites, and grey literature sources. The studies were searched up to
December 2019.
Selection Criteria: The interventions were divided into five broad categories: (a)
human factors (e.g., enforcement or road user education), (b) road design,
infrastructure and traffic control, (c) legal and institutional framework, (d) post‐
crash pre‐hospital care, and (e) vehicle factors (except car design for occupant
Campbell Systematic Reviews. 2024;20:e1367. wileyonlinelibrary.com/journal/cl2
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https://doi.org/10.1002/cl2.1367
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© 2024 The Authors. Campbell Systematic Reviews published by John Wiley & Sons Ltd on behalf of The Campbell Collaboration.
protection) and protective devices. Included studies reported two primary outcomes:
fatal crashes and non‐fatal injury crashes; and four intermediate outcomes: change
in use of seat belts, change in use of helmets, change in speed, and change in
alcohol/drug use. Studies were excluded if they did not report injury or fatality as
one of the outcomes.
Data Collection and Analysis: The EGM is presented in the form of a matrix with
two primary dimensions: interventions (rows) and outcomes (columns). Additional
dimensions are country income groups, region, quality level for systematic
reviews, type of study design used (e.g., case‐control), type of road user studied
(e.g., pedestrian, cyclists), age groups, and road type. The EGM is available online
where the matrix of interventions and outcomes can be filtered by one or more
dimensions. The webpage includes a bibliography of the selected studies and
titles and abstracts available for preview. Quality appraisal for systematic reviews
was conducted using a critical appraisal tool for systematic reviews, AMSTAR 2.
Main Results: The EGM identified 1859 studies of which 322 were systematic
reviews, 7 were protocol studies and 1530 were impact evaluations. Some studies
included more than one intervention, outcome, study method, or study region. The
studies were distributed among intervention categories as: human factors (n= 771),
road design, infrastructure and traffic control (n= 661), legal and institutional
framework (n= 424), post‐crash pre‐hospital care (n= 118) and vehicle factors and
protective devices (n= 111). Fatal crashes as outcomes were reported in 1414
records and non‐fatal injury crashes in 1252 records. Among the four intermediate
outcomes, speed was most commonly reported (n= 298) followed by alcohol
(n= 206), use of seatbelts (n= 167), and use of helmets (n= 66). Ninety‐six percent of
the studies were reported from high‐income countries (HIC), 4.5% from upper‐
middle‐income countries, and only 1.4% from lower‐middle and low‐income
countries. There were 25 systematic reviews of high quality, 4 of moderate quality,
and 293 of low quality.
Authors' Conclusions: The EGM shows that the distribution of available road
safety evidence is skewed across the world. A vast majority of the literature is
from HICs. In contrast, only a small fraction of the literature reports on the many
LMICs that are fast expanding their road infrastructure, experiencing rapid
changes in traffic patterns, and witnessing growth in road injuries. This bias in
literature explains why many interventions that are of high importance in the
context of LMICs remain poorly studied. Besides, many interventions that have
been tested only in HICs may not work equally effectively in LMICs. Another
important finding was that a large majority of systematic reviews are of low
quality. The scarcity of evidence on many important interventions and lack of
good quality evidence‐synthesis have significant implications for future road
safety research and practice in LMICs. The EGM presented here will help identify
priority areas for researchers, while directing practitioners and policy makers
towards proven interventions.
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1|PLAIN LANGUAGE SUMMARY
1.1 |Mapping the gaps in research evidence on the
effectiveness of road safety interventions
Reducing roadtraffic injuries (RTI) is an important goal for all countries.
Progress towards this goal requires evidence‐based evaluation of the
effectiveness of various road safety measures –interventions –in
improving road safety. Mapping the availability of evidence on the
effectiveness of road safety measures is the first step in evaluating the
‘shape and size’of the evidence, including its gaps.
1.2 |What is this evidence and gap map (EGM)
about?
A large majority of RTI happen in low‐and middle‐income countries
(LMICs). As many LMICs continue their development of highway
infrastructure, it is important for them to be able to evaluate the
effectiveness of various interventions in enhancing road safety. This
can help with efficient resource allocation.
Such an evaluation requires knowing what evidence is available
and where there are gaps in evidence. This EGM is the first step
towards understanding what evidence is available and from where.
1.3 |What is the aim of this EGM?
This EGM is a visual resource presenting a comprehensive overview
of existing knowledge about road safety and helps identify gaps in
research evidence.
1.4 |What studies are included?
The EGM includes systematic reviews and other literature that
reports impact evaluations assessing the effectiveness of road
safety interventions. The studies were classified based on the
target of the road safety interventions: human behaviour, road
infrastructure, vehicle design, post‐crash care and institutional
frameworks.
1.5 |What is the distribution of evidence?
Human factors such as enforcement and road user education (n=771),
and road design, infrastructure and traffic control (n= 661), were
the two most evaluated categories of interventions. These were
followed closely by the intervention category of legal and institutional
framework (n=424).
The least reported interventions were in the categories of post‐
crash pre‐hospital care (n= 118) and vehicle factors and protective
devices (n= 111).
Among the primary outcomes, fatal crashes were reported in
1414 records and non‐fatal injury crashes in 1252 records.
Among the four behavioural or intermediate outcomes, speed
(n= 298) and alcohol use (n= 206) were most frequently reported
followed by the use of seatbelts (n= 167) and use of helmets (n= 66).
In terms of income groups, 96% of the studies were from high‐
income countries, 4.5% from upper‐middle‐income countries, and
only 1.4% from lower‐middle and low‐income countries.
There were 25 systematic reviews of high quality, four of
moderate quality and 293 of low quality.
1.6 |What do the findings of the EGM mean?
The evidence map suggests that LMICs are highly underrepresented
across the studies. This has two main implications. First, the
effectiveness of a safety measure in a setting dominated by cars
may not translate to a setting with a mix of traffic that includes a
large proportion of pedestrians and motorised two‐wheelers.
Secondly, due to this bias in regional representation, the
interventions that are of greater importance in LMICs –such as
those aimed at increasing helmet use and designing safer buses and
cars for pedestrian safety –also remain poorly studied.
1.7 |How up‐to‐date is this map?
The authors searched for studies up to December 2019.
2|BACKGROUND
2.1 |Introduction
The World Health Organization (WHO) released its World Report on
RoadTrafficInjuryPreventionin2004(Pedenetal.,2004). This report
focusedonRTIandfatalitiesasaworldwide health problem and
included a summary of the known risk factors associated with road
traffic crashes and possible countermeasures that should be put in place
to control the problem. It also pointed out that without new or improved
interventions, RTI will be the third leading cause of death by the year
2020. The publication of this report spurred some national and
international agencies and civil society groups to give more attention
to the problem of road safety and a number of resolutions were passed
by the United Nations General Assembly, World Health Assembly and
the Executive Board of the WHO (WHO, 2004,2009,2011,2016).
As a follow‐up, three Global Ministerial Conferences on Road
Safety have been held in Moscow, Russia (19‐20 November 2009),
Brasilia, Brazil (18‐19 November 2015), and in Stockholm, Sweden
(19‐20 February 2020). At the close of the conference in Brasilia, the
2200 delegates adopted the Brasilia Declaration on Road Safety
through which they agreed on ways to halve road traffic deaths by
the end of this decade –a key milestone within the new Sustainable
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Development Goal (SDG) target 3.6 (Brasilia Declaration 2015). The
SDGtarget for 2020 was not achieved and the total number of RTI
and fatalities are still increasing in most countries of the world. The
ministers and heads of delegations at the third Global Ministerial
Conference in Stockholm in 2020 called for a first High‐Level
Meeting of the United Nations General Assembly on Road Safety at
the level of Heads of State and government to mobilize adequate
national leadership and advance international and multi‐sectoral
collaboration in all the areas covered by the Stockholm Declaration to
deliver a 50% reduction in deaths and injuries over the next decade
(i.e., by 2030) and Vision Zero by 2050. The Declaration also calls
upon the WHO to prepare an inventory of proven strategies and
initiatives from a wide variety of member countries that have
successfully reduced fatalities in member countries and have a report
readied for publication in 2024.
The WHO has also released four Global Status Reports on Road
Safety in 2009, 2013, 2015 and 2018. The final one being the Global
Status Report on Road Safety 2018 (GSRR18; WHO, 2018). These
reports give a broad assessment of the status of road safety in ~180
countries. The data were obtained from national governments using a
standardized survey form. The GSRRS18 shows that the overall
global road traffic fatality rate is 17.4 per 100,000, but there is a
great disparity by income and regions. Low‐and middle‐income
countries (LMICs) are reported to have the highest annual road traffic
fatality rates, at 24.1 per 100 000, while the rate in high‐income
countries (HICs) is lowest at 9.2 per 100,000. Over half of those who
die in road traffic crashes are pedestrians, bicyclists and users of
motorized two‐wheelers (MTW).
Traffic injuries have been steadily rising in LMICs, and now rank
in the top 10 causes of death (WHO, 2018). RTIs have become the
leading cause of death for young adults in most of these countries.
While most HIC have well‐established road safety policies, many
LMICs are in the process of establishing national regulatory agencies
and sustainable funding streams to support large‐scale interventions
that systematically address risky behaviours, trauma care, and the
safety characteristics of vehicle and road infrastructure.
LMIC are also growing their rural road and highway infrastructure.
National governments and international development agencies con-
sider the expansion of road infrastructure a key strategy for economic
and social development. In the last two decades, China has built a
highway system that rivals that of the United States, with plans for
substantial expansion (Xu & Nakajima, 2015; Yan, 2011). In India, the
rapid growth of the highway infrastructure is currently underway
because insufficient road transport is viewed as a key impediment to
industrial growth (Ghani & Goswami, 2013). Africa, where most people
do not have access to all‐weather roads, plans to expand its road
network by 6–10 times by 2040 (Programme for Infrastructure
Development in Africa, 2013). This increase in road infrastructure and
the number of vehicles is likely to result in an increase in RTIs unless
accompanied by appropriate evidence‐based road safety interventions.
The historical experience of many HICs shows that traffic injuries
can be reduced despite an increase in exposure (vehicle kilometres
travelled or greater network of highways). Until the 1960s, most
high‐income countries witnessed an increase in their traffic injury
burden. However, many of these countries successfully reduced their
road death toll through road safety legislation, setting up regulatory
authorities, and implementing evidence‐based interventions related to
road design, vehicle safety, trauma care, and traffic enforcement
(Bhalla et al., 2020). Consequently, the Decade of Action for Road
Safety 2011–2020, officially proclaimed by the UN General Assembly
in March 2010, and SDG 3.6, sought to save millions of lives by
building road safety management capacity; improving the safety of
road infrastructure; further developing the safety of vehicles; enhan-
cing the behaviour of road users; and improving post‐crash response.
Several national and international initiatives have been taken over the
past decade to promote and fund road safety initiatives around the
world. While there is reasonable agreement internationally on safer
designs of cars for occupant safety (except locally produced vehicles
like three‐wheeled scooter taxis, tuk‐tuks, jeepneys, etc.), there is a
lack of evidence‐based interventions in road and infrastructure design,
police enforcement and post‐crash care (Davey & Freeman, 2011;
Hauer, 2019; Wilson & Gangathimmaiah, 2017).
Since the proclaimed targets of 2011–2020 Decade of Action
remain far from being achieved, in October 2021, WHO kicked off
the Second Decade of Action for Road Safety 2021–2030, which
targets to achieve at least 50% reduction in road traffic deaths and
injuries by 2030. This was declared unanimously by governments
around the world through a UN General Assembly resolution. WHO
and the UN regional commissions, in cooperation with other partners
in the UN Road Safety Collaboration, have developed a Global Plan
for the Decade of Action that aligns with Stockholm Declaration.
Besides recommending actions that draw from proven and effective
interventions, this plan also highlights the importance of generating
evidence when it's lacking:
‘Academic and research institutions play an important role in
generating evidence to help government and other actors understand
(through epidemiological and risk analyses) the nature of the problem
as well as to identify effective solutions and strategies (through
intervention trials and implementation studies)’(WHO, 2021).
2.2 |Impact of RTI on society
Several high‐income countries have estimated the costs of road traffic
crashes over the past three decades. The methods used and costs
allocated have generated a great deal of discussion and debate, in
particular, because of the difficulty of putting monetary values on pain
and suffering. A study undertaken by the European Federation of Road
Traffic Victims, in collaboration with the Commission for European
Union, on the impact of road death and injury gives the following
qualitative conclusions regarding the effect of road traffic crashes on
victims (European Federation of Road Traffic Victims, 1997).
•Physical and mental impairment through road traffic injury can
have long‐term effects which deny victims the ability to maintain
their standard of living.
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•A large proportion of the relatives of dead and disabled victims, as
well as the disabled themselves, suffer psychological disorders.
The worst situation is that of the relatives of the dead.
•The bereaved are the worst affected –70% –by relationship
problems, communication difficulties and sexual problems. The
figure for relatives of disabled victims is 40%, and for the disabled
themselves 50%. After 3 years these problems do not decrease as
one would expect but worsen for each category by about 5 points.
•About 50% of the relatives of victims, and the victims themselves,
state that for extended periods they consume more psychotropic
products like tranquilizers, sleeping tablets, tobacco, alcohol and
drugs than before the incident.
•It is sometimes reported that due to the tragedy, the relationship
of the respondents with their normal social partners deteriorates.
•The capacity to enjoy life as before the crash tragically disappears
for 91% of the relatives of dead victims for the first 3 years. After
this period, the loss persists for long periods for 84% of them. For
many, this loss will be permanent.
We have quoted from this report extensively because it is
important to note that the economic costing of human tragedies can
only be used as an inefficient tool to understand the overall costs of
the problem.
2.3 |Why it is important to develop the EGM
In a recent paper Hauer (2019) states:
‘Over the past two decades or so progress has been
made towards evidence‐based practice. Research and
researchers provided valuable tools for practitioners
to use. But much of practice is still opinion‐based and
the role of research remains ambiguous. The first step
towards reform is to rethink and then to revamp the
research‐practice relationship. The reformed relation-
ship should be endowed with a purposeful structure,
one that cures what dysfunction there is and
promotes the generation of trustworthy evidence’.
Evidence‐based policy requires: (1) knowing what works, and (2)
implementing what has been established to work. This EGM focuses
attention on the former. Unfortunately, in the absence of local
research on road‐related safety interventions, roads and highways in
LMIC are being designed to safety standards of HIC without an
adequate understanding of the evidence base of existing standards.
For example, it is generally accepted that traffic calming measures
like chicanes, road narrowing, and roundabouts are effective in
reducing RTI (Bunn et al., 2003, Ewing & Dumbaugh, 2009; Rothman
et al., 2014). However, the effectiveness of some of these measures
in LMICs is not known. Vehicles like MTWs, which are common in
LMICs, wll likely not be affected by traffic calming measures in the
same way as cars. Many systematic reviews also point out the fact
that evidence for road safety interventions may be available for HICs,
but the same is lacking from LMICs (Mulvaney et al., 2015; Roberts &
Kwan, 2003). Here, it should be emphasized that just knowing what
works is not sufficient. There is an implementation gap, such that
even in HICs, many standards for vehicles, roads, and policing
activities are being promoted without the availability of adequate
scientific evidence regarding their effectiveness (Elvik, 2017;
Hauer, 2019).
SDG Target 3.6 for road safety aimed to halve the number of
global deaths and injuries from road traffic accidents by 2020 (United
Nations, 2017). However, considering the example of the WHO
European