A study was done to explore the suitability of intersection and arterial collision prediction models based on traffic conflicts, generated using the Paramics microsimulation suite and the Surrogate Safety Assessment Model (SSAM). A linear regression model and a generalized linear model with a negative binomial error structure were explored to correlate conflicts to crash rates, as well as the conflict-based models suggested by SSAM. The model predictions were compared to volume-based predictions and historical data from Toronto, Ontario, Canada. The volume- based predictions were calculated using a negative binomial generalized linear model, fitted to the same arterial and intersection sets used to fit the conflict-based models. The results show the predictions generated by a conflict-based model were comparable for intersections, but poor for arterials.

A study was done to explore the suitability of intersection and arterial collision prediction models based on traffic conflicts, generated using the Paramics microsimulation suite and the Surrogate Safety Assessment Model (SSAM). A linear regression model and a generalized linear model with a negative binomial error structure were explored to correlate conflicts to crash rates, as well as the conflict-based models suggested by SSAM. The model predictions were compared to volume-based predictions and historical data from Toronto, Ontario, Canada. The volume- based predictions were calculated using a negative binomial generalized linear model, fitted to the same arterial and intersection sets used to fit the conflict-based models. The results show the predictions generated by a conflict-based model were comparable for intersections, but poor for arterials.

Traffic crashes tend to occur at relatively greater frequencies at particular locations, at particular time periods, and for particular subsets of drivers and vehicles. It is well recognized among the road safety community that crash-risk is highly elevated when inclement weather conditions occur in the winter. To present, most of the road safety studies focus on event-based analysis or seasonal analysis and give little attention to explore high-risk conditions at the daily temporal scale. The purpose of the study is to advance our understanding of high-risk crash conditions at the daily level and their occurrences in Southern Ontario, Canada. The study explores different definitions of high-crash days, and quantifies the influences of weather conditions, risk exposure, months and timing of precipitation on the likelihood of a high-crash day occurring using binary logistic regression model. Additionally, an approach for estimating the relative risk exposure using available traffic count data has also been developed. The results of the study show a small proportion of high-crash days are responsible for a considerable amount of traffic crashes during the winter. The risk of traffic crash is twice as high on high-crash days in comparison to non-high-crash days. The modeling approach well-fits the data and shows that winter weather conditions have significant influence on high-crash days with results being mostly consistent across the four study areas, Toronto, the Area Surrounding Toronto, London and the Area Surrounding London. Low temperature, heavy snowfalls, high wind speeds, high traffic volumes, early winter months, occurrence of precipitation in both morning and evening increase the odds of high-crash days to a large extent. The results of study could help to pre-schedule traffic operation and enforcement, to effectively distribute road safety resources and personnel, and to create situational awareness among road users and other stakeholders.

The objectives of this research were to explore ways to assess the safety performance of (predominantly two-lane) rural highways in New Zealand (NZ) and in particular identify driver/road/environmental factors affecting crashes on rural curves. Following a wide-ranging literature review, the Interactive Highway Safety Design Model (IHSDM) was identified as worthy of further investigation for adaptation to use in NZ. To help with this investigation, a comprehensive database was developed of road, traffic, crash and environmental data for all NZ State Highways, divided into variable-length road elements. A number of tasks were identified and undertaken to adapt IHSDM for general use here, including calibrating the Crash Prediction Module (CPM), developing a Design Policy file based on local agency standards, and developing an importing routine for NZ highway geometry and crash data. To assess the effectiveness of IHSDM for predicting the relative safety of rural road alignments, a series of tests were undertaken to confirm its appropriateness for use in NZ. These included “before and after” design consistency checks of a bridge replacement, a “before and after” crash comparison of a major highway realignment, and checks of actual versus predicted crash numbers along longer lengths of highway in varying terrain. These initial investigations have shown that IHSDM is a promising tool for safety and operational assessment of highway alignments (both existing and proposed) in NZ. Incorporating crash history data generally improves IHSDM’s accuracy in crash numbers, and appears to provide a better level of “local calibration” than by using sub-national (e.g. regional or terrain-specific) calibration parameters. Reported fatal/injury crash data generally provide more robust and precise measures than non-injury crashes. Correct specification of the extreme attributes of sub-standard elements (e.g. minimum radius, maximum roadside hazard) appears to be crucial to getting suitably accurate crash estimates on existing alignments. However, IHSDM’s current lack of consideration for bridges and inconsistent adjacent elements are notable omissions that limit the ability of the CPM to assess sub-standard existing routes with as much accuracy as well-designed newer alignments.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

It has been well proven that as the skid resistance of a road surfacing decreases, the number of loss of control type crashes increases, causing road death and injuries. However, the management of skid resistance of road surfacings continues to be difficult due to the inherent and sometimes random variation in skid resistance levels over time. This study is an investigation and analysis of seasonal and short term variation of measured skid resistance in two phases. Phase 1: Regular field monitoring was undertaken using the GripTester and the Dynamic Friction Tester measurement devices on seven sites in the Auckland and Northland Regions of New Zealand was undertaken over a three year period. The effects of temperature, rainfall, contaminants, new surfacings, geometric elements and aggregate properties were analysed to investigate factors that initiate changes in the measured skid resistance of pavement surfacings. Phase 2: Laboratory prepared samples were constructed for accelerated polishing and skid resistance testing of four different aggregates (two greywackes, a basalt and an artificial iron-making melter slag aggregate). The samples were polished in an accelerated polishing machine to an ‘equilibrium skid resistance’ level (Stage 1 polishing). Contaminants were then added to the accelerated polishing process to determine the effect of varying additive, particle size and hardness in an attempt to simulate seasonal and/or short-term variations that occur in the field. The results have demonstrated that significant and previously unpredictable variations (greater than 30%) in measured skid resistance can occur over short time periods. These variations cannot be explained by any one factor. They are the result of a number of inter-related factors, including the geological properties of the aggregates and the contaminants themselves, the previous rainfall history, the road geometry, the calendar month of the year and (depending upon the measurement device), the temperature during testing. The laboratory tests demonstrate that accelerated polishing tests of aggregate samples could be prepared for testing by the Dynamic Friction Tester and that significant variations in measured skid resistance could be simulated on various aggregates in the laboratory by the addition of contaminants. The results of the testing and addition of contaminants on various aggregates resulted in significant behavioural differences which were related to the geological properties of the aggregates themselves, as well as the contaminants used in the accelerated polishing process. The findings of the research have specific relevance to three areas of industry; Road Controlling Authorities who are primarily interested in skid resistance policy, standards and management, Road Asset Managers who operate, maintain and manage condition level and the safety aspects of the road network and Crash Investigators who collect and analyse crash data primarily for legal proceedings. All three of these industry organisations need to clearly understand the inherent variability of skid resistance, the factors involved and the effects that geological and environmental variations have on skid resistance measurement. / Specific appreciation (as outlined below) is given to the significant industry partners/supporters that have helped support the research in many different ways. Firstly, I must give special thanks to Works Infrastructure Limited who have supported the research both financially and with resources almost from the outset of the research programme. The field testing data collection in the Northland Region of New Zealand would not have been possible without the support of the Whangarei Works Infrastructure team which included Peter Houba, Peter King, Matthew Findlay, Glen Kirk and the temporary traffic control team headed by Derek Phillips. Thanks also go to the Auckland Works Infrastructure testing laboratory which supplied aggregate supplies for laboratory sampling and testing and whose technicians also undertook Polished Stone Value tests on the aggregate samples. Special thanks are also given to Michael Haydon and David Hutchison from the technical management team of Works Infrastructure who have always been willing to listen to my requests and the many discussions that we have had on aspects of skid resistance, policy and technical matters. Pavement Management Services and especially Dr John Yeaman and Daniel Rich for their support for the research programme from the beginning, and secondly for financially contributing to the purchase of the Dynamic Friction Tester for the static field testing and the laboratory tests. Achnowledgement is also given to The Ports of Auckland and especially Jo Campbell of the AXIS Intermodal group that allowed access to the rail grid site as a field-testing site outside of normal port operation hours. Transit New Zealand head office staff (Mark Owen, David Cook and Chris Parkman) are also thanked for their support of the research and in enabling access to historic SCRIM and RAMM data on the Transit New Zealand state Highway network. Land Transport New Zealand (formerly Transfund New Zealand) are acknowledged for their significant financial support of the research, in terms of the Land Transport New Zealand Research project that allowed the field research data collection and analysis programme to continue for a further year and for the extension to the controlled laboratory testing.

Os critérios atualmente empregados para a definição da configuração do separador central em rodovias levam em consideração principalmente a massa de exposição ao risco. Para isso, analisam a largura do canteiro central e o VDM (volume diário médio). No entanto, para implantação de rodovias em pista dupla ou para a duplicação de rodovias existentes, a definição da largura do canteiro central bem como do possível emprego de dispositivos de contenção central muitas vezes não é uma tarefa simples, pois depende da análise conjunta de alguns fatores como os custos da movimentação de terra, da desapropriação, das soluções possíveis para drenagem, do atendimento à distância de visibilidade de parada, entre outros. Além disso, deve ser avaliado qual o impacto da configuração proposta para a separação central da rodovia na redução do custo social dos acidentes. Essa ultima avaliação é mais delicada e de difícil mensuração. Este texto apresenta a revisão bibliográfica dos principais critérios existentes nacionais e internacionais com relação ao separador físico central e aborda a questão das características dos acidentes que envolvem saída de pista. Através do estudo de caso de uma rodovia hipotética, foram analisados conjuntamente os custos de implantação da rodovia, a distância de visibilidade disponível e os custos dos acidentes para diferentes configurações de canteiro central. Por fim, foi apresentada uma análise benefício / custo incremental que, após avaliação mais precisa dos custos sociais dos acidentes, poderá ser empregada para tomada inicial de decisão quanto ao separador físico central da rodovia a ser empregado. / Criteria currently used to choose median or median barriers configurations on divided highways take into account mainly the risk exposure mass. For this, median width and ADTV (average daily traffic volumes) are analyzed. However, for deployment of divided highways or duplication of existing ones, the definition of median width as well as the potential use of median barrier is not always a simple task, because it depends on the joint analysis of factors such as earthmoving costs, land acquisition costs, drainage possible solutions, stop sight distance, among others. Furthermore, the impact of the proposed median configuration in reducing the social cost of accidents should also be estimated. This thesis presents a literature review of existing national and international median solution criteria and address the characteristics of run off the road accidents. Through a case study of a hypothetical highway, were analyzed jointly highway construction costs, available sight distance and accident costs for different widths of median. Finally, an analyze cost / benefit incremental, that could be used for making the initial decision about the central physical separator highway after proper calibration of social costs of accidents is presented.

This licentiate thesis discusses moral issues associated with road safety work, with a particular emphasis on the Vision Zero (VZ) goal and its interventions. The licentiate thesis contains three articles and an introduction that briefly discusses issues and arguments presented in the articles. The first article, identifies, systematically categorizes and evaluates arguments against VZ. Moral, operational, and rationality related criticisms against the adoption and implementation of VZ are identified and discussed.  The second article in this thesis seeks to reconcile the methods of Cost Benefit Analysis (CBA) and VZ in road safety decision making. CBA has been and still is a major decision making tool in road transport and traffic safety work. However, proponents of VZ question the use of CBA in road safety and transport decision making on methodological and ethical grounds. In this paper, we locate the philosophical roots of the conflicting views promoted by proponents of CBA and VZ. Then we try to identify ways through which the two methods can be made compatible. The third and final paper uses VZ as a normative framework to explore and analyse the Addis Ababa road safety work. The aim of the paper is twofold. First, the paper seeks to examine how road safety problems are actually understood by those responsible for road safety at the local level. To this end, government policy documents, reports and other relevant sources where consulted to identify how road safety problems are framed, who is assigned responsibility for addressing road safety problems and through what interventions. Second, the paper aims to examine road safety work in the city from a normative point of view, i.e., what is the best, or most adequate, way of framing the problem, and who should be given the responsibility for addressing the problem and by what measures. It is argued that enhancing road safety in the city requires adopting a broader view of causes of road safety problems, and emphasizing the responsibility of actors that shape the design and operation of the traffic system and the safety of its components. / I denna licentiatavhandling diskuteras moraliska frågor i samband med trafiksäkerhetsarbetet, med särskild tonvikt på nollvisionsmålet och dess insatser. Avhandlingen innehåller en introduktion och tre artiklar. I denna svenska sammanfattning kommer jag kortfattat att presentera de tre artiklarna. 1997 antog Sverige Nollvisionen som det slutliga målet för trafiksäkerhetsarbetet. Regeringspropositionen konstaterade att det långsiktiga målet med trafiksäkerhetsarbetet är att eliminera dödliga och allvarliga skador från vägsystemet. Den betraktade den fortsatta förekomsten av sådana krascher som moraliskt oacceptabel. För att uppnå målet föreslog regeringen att vägsystemets utformning och funktion skulle anpassas till Nollvisionens krav. Detta krav innebär erkännandet och främjandet av två grundläggande fakta om trafikanternas karaktär i vägsystemet, det vill säga deras fysiska bräcklighet och kognitiva felbarhet. Regeringspropositionen konstaterade att de då rådande tillvägagångssätten för trafiksäkerhetsarbete ignorerade dessa grundläggande fakta om trafikanternas karaktär. Som svar föreslog regeringen att dessa fakta skulle vara utgångspunkten för trafiksäkerhetsarbetet och att utformning och drift av vägsystemet ska göras på ett sådant sätt att förutsägbara trafikantmisstag inte leder till dödlig eller allvarlig hälsoförlust. Enligt Nollvisionen ligger det yttersta ansvaret för att utforma vägsystemet på ett sådant sätt hos de så kallade systemformgivarna. Dessa är statliga och icke-statliga aktörer som ansvarar för utformningen och driften av vägsystemet och dess komponenter, till exempel fordonstillverkare, vägkonstruktörer och trafikplanerare. Sedan införandet av Nollvisionen har trafiksäkerheten avsevärt förbättrats i Sverige och i de andra länderna som följde en liknande strategi. Emellertid har Nollvisionens mål och vissa insatser som främjats för att komma närmare det målet allvarligt kritiserats både i Sverige och på andra håll. I den första artikeln identifierar, kategoriserar och utvärderar vi argument mot Nollvisionen. Enligt vår analys kan kritik av Nollvisionen indelas i moralisk, operativ och rationalitetsrelaterad kritik. Moralisk kritik mot Nollvisionen är främst den som riktar sig mot etiska premisser och antaganden som Nollvisionens policy grundar sig på. Bland annat ifrågasätter denna kritik det etiska antagandet bakom Nollvisionen, att dödliga och allvarliga skador är moraliskt oacceptabla. Ett viktigt argument är att, eftersom de ekonomiska resurserna är begränsade, borde offentliga pengar läggas på policyer och insatser som garanterar större nytta för samhället än andra tillgängliga alternativ. I praktiken är detta tankesätt dominerande och används ofta som berättigande för att inte investera i trafiksäkerhet. Liknande resonemang förs också fram för att berättiga utvecklingen av policyer och åtgärder som påverkar trafikanternas säkerhet på ett negativt sätt. I allmänhet säger kritiker att det ofta är moraliskt acceptabelt att äventyra säkerheten så länge det ger större fördelar för samhället. Andra kritiker avvisar godtagandet av Nollvisionens etiska princip och hävdar att trafikanter frivilligt har gått med på att ta ansvar för varje olycka som kan drabba dem i vägsystemet. Genom att gå in i vägsystemet och använda det, menar dessa kritiker, har trafikanterna i tystnad samtyckt till risken för dödlig eller allvarlig hälsoförlust. Vi tyckte att detta argument var svagt eftersom det inte finns någon anledning att tro att folk faktiskt accepterar att bli dödade och allvarligt skadade när de går in i vägsystemet. Däremot är det troligare att om de presenterades med ett säkrare och tryggare vägsystem skulle säkert de flesta välja att använda det säkrare systemet än ett där chansen att bli dödad och allvarligt skadad är stor. Övrig moralisk kritik mot Nollvisionen riktar sig mot specifika insatser som främjas för att öka säkerheten, t.ex. användning av säkerhetskameror (t.ex. att de kränker integriteten och samlar in för många känsliga personuppgifter), polisarbetet (t.ex. att det ofta är oproportionerligt och ineffektivt), trånga gator (t.ex. att de förhindrar snabba förflyttningar av utryckningsfordon), hjälmar och säkerhetsbälten (t.ex. att de kränker människors autonomi och frihet). Kritik relaterad till processrättvisan och beslutsprocesser i Nollvisionens beslutsfattande ingår också i denna kategori. I allmänhet visar vår analys att några av dessa moraliska argument mot Nollvisionen förtjänar noggrann uppmärksamhet och därför är det viktigt att fortsätta att studera och undersöka genomförandet av policyn ur ett moraliskt och socialt rättviseperspektiv. Den andra kategorin av kritik som vi kallar rationalitetsrelaterad kritik, riktar sig mot rationaliteten i att anta och driva Nollvisionen som sådan. Man sätter upp mål i det privata och offentliga livet för att människor vill uppnå de situationer som målen syftar på. För detta ändamål krävs ofta att målen måste vara specifika, mätbara, uppnåeliga och tidsbegränsade (SMART) för att kunna vägleda och motivera på rätt sätt. I den filosofiska 34 litteraturen om målrationalitet hänvisar man till mål som i tillräcklig utsträckning vägleder och motiverar handlingar mot måluppfyllelse som prestationsfamkallande mål. Även om det har hävdats att Nollvisionen är ett prestationsframkallande mål på grund av dess handlingsvägledning och motiverande roller i trafiksäkerhetsarbetet, har vissa kritiserat Nollvisionens mål som orealistiskt, ospecifikt, kontraproduktivt och demotiverande. I allmänhet hävdar kritiker att Nollvisionen är ett irrationellt policy-mål. Vi anser att den första kritken, att Nollvisionen är orealistisk, bygger på ett diskutabelt antagande om att målen antingen är realistiska eller orealistiska. Vi hävdar dock att en sådan binär beskrivning av måluppfyllelsekrav är förminskande eftersom den ignorerar det faktum att måluppfyllelse ofta sker gradvis. Dessutom visar empiriska belägg att även svåra och ambitiösa trafiksäkerhetsmål kan uppnås till en avsevärd nivå om effektiva och beprövade insatser främjas proaktivt. Vi hävdar att ett visionärt mål fortfarande kan vara värt att sträva efter så länge det kan uppnås till en betydande nivå. Vissa kritiker hävdar dessutom att Nollvisionens mål är för vagt för att korrekt vägleda och samordna åtgärder. Antagandet är att eftersom det inte är tydligt formulerat, skulle det vara problematiskt för agenter som eftersträvar det att ha en klar förståelse för vad de vill uppnå men också hur de ska utvärdera sina framsteg med tiden. Vissa hävdar dessutom att det faktum att sträva efter oprecisa och orealistiska mål skulle vara kontraproduktivt och demotiverande för agenter som strävar efter sådana mål. Vår analys visar att åtminstone när det gäller Sverige är det trafiksäkerhetspolitiska målet det tydligast uttalade policy-målet inom vägtransportpolitiskt område. Det finns inte endast ett tydligt uttalande om vad det slutliga policy-målet är, utan också det faktum att det övergripande långsiktiga målet har gjorts operativt och mer specifikt tack vare uppdelningen i delmål för att göra det mer relaterbart och exakt för agenter som är inblandade i trafiksäkerhetsarbete. En adekvat bedömning av inverkan Nollvisionens mål har på agenternas motivation skulle kräva en empirisk undersökning av dess karaktär, dess praktiska genomförande och dess konsekvenser för, bland annat, intressenters motivation. Bland annat skulle detta kräva en utredning för att fastställa om Nollvisionens mål har kunnat generera den nödvändiga energin och ansträngningen som behövs för att minska problemet på ett betydande sätt eller inte. Det är uppenbart att om ansträngningar för att uppnå trafiksäkerhet, efter flera år ägnade åt att implementera Nollvisionen, sjunker till den punkt där de befann sig före Nollvisionen, och trafiksäkerhetsbyråer och intressenter upphör eller saknar intresse för trafiksäkerhetsarbete, då kan Nollvisionen anses ha lett till att demotivera agenter. Det verkar, åtminstone i Sverige, som om antagandet av policy-målet har lett till en betydande ökning av intressenternas engagemang i trafiksäkerhetsinsatser. Statliga och privata medel för trafiksäkerhetsinsatser, särskilt för säkrare väginfrastruktur, fordonssäkerhet och forskning, har uppvisat betydande förbättringar sedan antagandet av Nollvisionen. Den sista kategorin av kritik som vi identifierar och diskuterar i den första artikeln är den som vi kallar operativ kritik mot Nollvisionen. Denna kritik riktar sig mot den operativa strategin i Nollvisionen, det vill säga den gäller de praktiska metoder som används för att genomföra insatser för att förbättra säkerheten. De viktigaste argumenten i denna kategori är argumenten relaterade till Nollvisionens ansvarsbeskrivning för trafiksäkerhet. Vissa kritiker har hävdat att nollvisionens betoning av systemformgivarnas ansvar skulle leda till övermod hos enskilda trafikanter, särskilt hos motorfordonsförare. Därför argumenteras det för att tonvikten snarare bör läggas på större ansvar hos trafikanterna. Vi fann detta argument felaktigt. Det finns ingen logisk eller empirisk anledning att tro att antagandet gällande större ansvar från systemformgivarnas sida leder till övermod i vägtrafiken. Det finns inga starka empiriska belägg, åtminstone i trafiksäkerhetsarbetet, som visar att detta faktiskt är fallet. Kritiken tycks dessutom försumma det faktum att enskilda trafikanter fortfarande är kopplade till sitt gamla ansvar när det gäller att bete sig och agera säkert i vägtrafiken. Faktum är att vissa länder som engagerat sig i Nollvisionen, som Sverige, är kända för sin strikta kontroll av trafikantansvar genom striktare krav på skicklighet och beteende. En annan aspekt av kritiken mot Nollvisionens ansvarsfördelning är synpunkten som ifrågasätter frånvarokodade lagkrav för främjandet och utvärderingen av systemformgivarnas ansvar. Även om Nollvisionen lägger det yttersta ansvaret på systemformgivarna saknas det enligt argumentet ett sätt att kontrollera om systemformgivarna verkligen agerar i enlighet med det som förväntas av dem. Vi hävdar att denna kritik är relevant. Vi tror att det för närvarande saknas empiriska bevis för att avgöra om det faktum att ge laga kraft åt systemforgivarnas ansvar skulle bidra effektivt till säkerheten i vägsystemet. I Sverige har exempelvis förekomsten av andra kontrollmekanismer än juridiska straffkontroller för 36 systemformgivarnas ansvar gjort det irrelevant för regeringen att ge laga kraft åt systemformgivarnas ansvar. Den andra artikeln i denna avhandling syftar till att förena metoden för kostnadsnyttoanalys och Nollvisionen i beslutsfattande om trafiksäkerhet. Kostnads-nyttoanalys har varit och är fortfarande ett viktigt beslutsverktyg inom vägtransporten och trafiksäkerhetsarbetet. Enligt denna princip är det moraliskt motiverat att förhindra risk endast när nyttan av att göra det överväger kostnaden. Detta skulle kräva att man påvisar att varje krona som läggs på trafiksäkerhetsarbete ger samhället mer nytta än någon annan alternativ användning av pengarna. Följaktligen fastställs relevansen och den moraliska godtagbarheten hos specifika trafiksäkerhetsmål och insatser på basis av nyttan och kostnadsöverväganden för samhället. Som kort sagt ovan i detta avsnitt, används ofta resultatet av överväganden relaterade till kostnads-nyttan för att berättiga varför utgifter för säkerhet inte är värda att göras ur ett moraliskt, ekonomiskt och samhällsperspektiv. Dessutom är det vanligt att i många länder använda kostnad-nyttoanalys för att fastställa och sätta upp trafiksäkerhetsmål som anses vara ekonomiskt optimala. Förespråkarna för Nollvsionen hävdar att det bland annat att inte är önskvärt att lämna trafiksäkerhetsmålen till kostnads-nyttoberäkningar ur en moralisk synpunkt. Det står i Nollvisionen att det enda moraliskt acceptabla målet för trafiksäkerhetsarbetet är noll dödliga och allvarliga skador. Dessutom, i den utsträckning man känner till effektiva och beprövade strategier bör de genomföras för att rädda människor från att bli dödade eller allvarligt skadade. I allmänhet avvisar förespråkarna för Nollvisionen beslutsfattande baserade på en ren kostnadsnyttoanalys av metodiska och etiska skäl. Nollvisionens syn att dödliga och allvarliga skador i vägsystemet är oacceptabla är moraliskt tilltalande. På samma sätt är kostnads-nyttoanalysen (CBA) främst avsedd att främja ekonomisk effektivitet. I den här artikeln argumenterar vi för att Nollvisionen och kostnads-nyttoanalys är båda baserade på rimliga principer och kan göras kompatibla. Vi identifierar och diskuterar sedan sätt på vilka Nollvisionen och kostnads-nyttoanalysen kan göras kompatibla. I den tredje artikeln undersöker vi policydokument angående trafiksäkerhetsarbete i Addis Ababa för att undersöka hur trafiksäkerhetsproblem faktiskt uppfattas av de som är ansvariga för trafiksäkerhetsarbetet. En viktig egenskap i det nuvarande trafiksäkerhetspr oblemet är att detta problem oproportionerligt påverkar låg- och medelinkomstländer. Dessa länder står för cirka 90 % av dödsolyckorna på vägen, medan de bara äger mindre än 50 % registrerade motorfordon i världen. Den stora omfattningen av dödsolyckor och allvarliga skador i dessa delar av världen visar vikten av att undersöka effektiviteten, verkningsfullheten och rationaliteten av policyer och insatser som främjas i dessa länder. Dessutom är det också viktigt att undersöka trafiksäkerhetsarbetet i dessa delar av världen ur ett normativt perspektiv. Genom att anta Nollvisionens tillvägagångssätt för trafiksäker hetsarbete som en normativ teoretisk ram, bedömer vi trafiksäkerhetsarbetet i denna stad med avseende på dess målsättningsaspekter, problemformulering, strategier och insatser för trafiksäkerhetsarbete och ansvarsbeskrivning för trafiksäkerhet i staden. Vår analys visar både på likheter och skillnader mellan Nollvisionen och Addis Ababas trafiksäkerhetsarbete. Vi hävdar i detta dokument att en förbättring av trafiksäkerheten i staden kräver att man främjar en bredare syn på orsakerna till trafiksäkerhetsproblem och fördelar och tilldelar ansvar till viktiga intressenter som har avsevärt inflytande på vägtrafiksystemets utformning och drift. / <p>QC 20210929</p>