Anish Khadka

Connected and autonomous vehicles (CAVs) are expected to reshape future traffic operations, but their potential contribution to road network resilience during large-scale disruptions remains underexplored. This study evaluates the resilience of a regional road network under varying CAV penetration levels using a microscopic traffic simulation framework. A hypothetical Wellington Fault earthquake scenario is adopted to represent post-disaster network conditions across multiple recovery stages. Network performance is assessed using connectivity and serviceability indicators, including connectivity retention, demand satisfaction, completion efficiency, and system realization, together with average travel time and generalized system cost. Results show that the effect of CAVs depends strongly on network state and recovery stage. Under fully operational or highly fragmented, low-density conditions, CAVs have limited influence on performance. In contrast, during intermediate and later recovery stages, higher CAV penetration improves network throughput and reduces queue delays under oversaturated conditions. The findings also show that conventional travel-time measures can underestimate system-wide delays when a substantial share of demand cannot be served immediately. By integrating mixed traffic behavior, recovery dynamics, and performance measures capturing both completed and unserved trips, this study provides insights for disaster recovery planning, network restoration prioritization, and transport system preparedness for mixed CAV and human-driven traffic.

Connected and autonomous vehicles (CAVs) are expected to reshape future traffic operations, but their contribution to road network resilience during large-scale disruptions remains underexplored. This study develops a microscopic traffic simulation framework to evaluate regional road network resilience under varying CAV penetration levels and post-disaster recovery stages. A hypothetical Wellington Fault earthquake scenario is adopted to represent network disruption. Resilience is assessed using connectivity and serviceability indicators, together with travel time and generalized system cost accounting for completed and unserved demand. Results show that CAV benefits depend strongly on network state and recovery stage. While CAVs have limited influence under fully operational or highly fragmented, low-density conditions, higher penetration levels improve throughput and reduce delays in partially restored, oversaturated networks. The findings demonstrate that conventional travel-time measures can underestimate system-wide impacts when substantial demand cannot be immediately served. The results provide insights for post-disaster recovery planning and future mixed-traffic operations.

The Wellington region faces significant seismic risk, with a major rupture of the Wellington Fault expected to severely disrupt road network operability. This study applies a simulation-based framework to assess post-disaster road network resilience using a large-scale mesoscopic traffic model of the North Island. The framework integrates multi-source demand estimation and staged recovery scenarios, as well as trip- and corridor-level performance metrics to evaluate accessibility loss and traffic redistribution. Results indicate widespread disruption, with 9%, 5%, and 4% of trips becoming infeasible three days, two weeks and three months post-disaster. Severe congestion emerges on constrained urban detours, while prolonged highway corridor closures isolate the Hutt Valley and Wairarapa. The findings demonstrate the value of simulation-based stress testing for resilience-oriented transport planning.

Background: Injuries cause significant harm and may lead to disability yet are largely preventable. Understanding the epidemiology and determinants of injury in any given context is an essential step towards effective prevention. In Nepal, surveys suggest that injuries on the road, at home and at work are a problem, but in the absence of injury surveillance, robust death registration or police records, the true burden is unclear. For those who are injured, access to prehospital care is variable. Objectives: To understand the epidemiology of injuries. To identify potentially modifiable risk factors to inform the development of prevention interventions. To build capacity and capability for injury prevention research. Design: Observational, secondary data analysis and qualitative methods were used. We worked with communities, practitioners and stakeholders to identify potential participants, develop study protocols and disseminate findings. Setting: Nepal. Participants: Patients, communities and road users, health system practitioners and managers, professionals (e.g. police, engineers, journalists) and local and national decision-makers. Main outcome measures: Epidemiological evidence of the burden of injuries, evidence to inform future intervention development. Data sources: Participants, health services, police and information in the public domain. Review methods: Reviews were conducted systematically with evidence synthesised narratively. Results: The Nepal Injury Research Centre was established and a cadre of researchers trained. Three researchers and our data manager completed Master’s degree courses, and all researchers developed their skills by leading at least one project from protocol development through to publication. A review of publications reporting injuries indicated that existing epidemiological evidence mostly arose from case series at high risk of bias. A review of existing legislation showed policy gaps and incomplete implementation or enforcement. Surveillance studies and a household survey showed the high burden of injuries at home, at work and on the roads, and the neglected issue of suicide. Previously unreported inequalities by age, sex, ethnic group and income level were identified. Existing health, police and death registration data systems are at high risk of under-reporting and misclassification. Road traffic injury emerged as a major concern: road users fear being injured as pedestrians, passengers or drivers; the economic burden of road injuries has increased threefold over 8 years; and potentially modifiable risk factors were identified. The provision of first-response services is highly variable, and the public and practitioners are fearful of prosecution in the event of poor outcomes. We found it is feasible to train the traffic police in first response and for them to use their skills at traffic collisions. Research priorities for suicide prevention were identified. Limitations: Studies were limited by the quality of the data available through existing systems, with data often incomplete or poorly coded. Our studies were largely conducted in one district with topography typical of many areas of Nepal. However, our findings may not be generalisable to all districts. Conclusions: Our programme identified the inequitable and significant burden of injuries in Nepal. There is the potential to develop existing legislation and health and transport systems to reduce the incidence and consequences of injury. Future work: Research should focus on interventions to reduce injury risk on the roads and at home/work, to develop the first-response system and standardise care and to strengthen injury data systems. Funding: This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Global Health Research (GHR) programme as award number 16/137/49.

Background: Road traffic injuries are the 12th leading cause of mortality globally. Nepal, one of the least developed countries in the world, has a rapidly rising rate of road traffic-related morbidity and mortality. There is incomplete reporting of traffic crashes in Nepal in the last three World Health Organization global status reports on road safety. Together with poor-quality coding of crashes, essential information to inform prevention interventions or make international comparisons is lacking. Objectives: The study aimed to critically analyse routinely collected traffic police data in Makwanpur district, Nepal, to identify the road user groups most likely to be involved and injured in traffic crashes in this part of the country. Design: Secondary data analysis. Setting: Makwanpur district, Nepal. Data sources: Road traffic crash records from the District Traffic Police Office, Makwanpur, over 2 years (April 2017–March 2018 and May 2019–April 2020). Data were extracted from paper-based records onto an electronic database, and the data were analysed descriptively using the Statistical Package for the Social Sciences version 24.0 (IBM Corporation, USA). Results: There were 291 crashes recorded in 2017–8 and 435 crashes in 2019–20. Two-wheeled vehicles (motorcycles/scooters) were the most frequently involved in police-reported crashes (35.5%). For most crashes (419/726, 58%), no cause was documented in the police record. Road users involved in crashes were mostly riders or passengers of motorised two-/three-wheelers (33.4%), four-wheeled vehicles (19.9%) or buses (16.7%). Of fatal injuries, 31.2% were riders or passengers of motorised two-/three-wheelers, and 24.8% were pedestrians. Limitations: The data used represent crashes reported to the traffic police and therefore underestimate the true number of crashes and injuries. At the end of the second period of study, local movement restrictions associated with the COVID-19 pandemic lockdown limited the traffic on the roads, resulting in fewer crashes in March and April 2020. In most crash records, there were missing data, limiting the ability to determine contributory factors with confidence. Conclusion: This study contributes to the evidence gap by describing crashes and mortality data by vehicle type and road user category. The findings suggest that the number and rates of crashes may be increasing over time. Action to improve the quality and completeness of data routinely collected by the traffic police is needed; a piloted web-based Road Accident Information Management System has the potential to support improved routine data collection. Future work: The data indicate crashes occurring in one district over 2 years. To better understand the apparent increase in crashes, an analysis over a longer period, and over multiple districts, would be necessary. Funding: This article presents independent research funded by the National Institute for Health and Care Research (NIHR) Global Health Research programme as award number 16/137/49.

Background Police road crash and injury data in low-income and middle-income countries are known to under-report crashes, fatalities and injuries, especially for vulnerable road users. Local record keepers, who are members of the public, can be engaged to provide an additional source of crash and injury data. Methods This paper compares the application of a local record keeper method to capture road crash and injury data in Bangladesh and Nepal, assesses the quality of the data collected and evaluates the replicability and value of the methodology using a framework developed to evaluate the impact of being a local record keeper. Outcome Application in research studies in both Bangladesh and Nepal found the local record keeper methodology provided high-quality and complete data compared with local police records. The methodology was flexible enough to adapt to project and context differences. The evaluation framework enabled the identification of the challenges and unexpected benefits realised in each study. This led to the development of an 11-step process for conducting road crash data collection using local record keepers, which is presented to facilitate replication in other settings. Conclusion Data collected by local record keepers are a flexible and replicable method to understand the strengths and limitations of existing police data, adding to the evidence base and informing local and national decision-making. The method may create additional benefits for data collectors and communities, help design and assess road safety interventions and support advocacy for improved routine police data.

Accurate road crash reporting is essential for evaluating road safety interventions and plans. Under-reporting of road traffic crashes, injuries, and fatalities in police records has been widely de...