BACKGROUND: Only prospective cohort studies can capture changes in work conditions and their effects on health. Such studies are rare in bus drivers, despite their high rates of injuries and diseases. The three existing cohorts have limited exposure data, collected at baseline and thus uninformative on exposure and exposure-effect dynamics. Therefore, we aimed to develop the Swiss Transport Personnel Health Cohort (TRAPHEAC) and to anticipate and prevent potential bias. METHODS: To set up the study protocol, we first organized the stakeholder consultation and available data inventory. Second, we mapped the exposure-outcomes pairs to list the most prevalent occupational hazards, and conducted exposure measurement campaigns. Third, we built the Swiss Bus-Exposure Matrix for physical-chemical hazards and Bus-Ergonomics Matrix for visual and biomechanical constrains. These matrices contain 705 bus models operated in Switzerland since 1980 and enable assessing current and past exposure when merged with bus drivers' work histories. RESULTS: We opted for an original study design combining prospective cohort part starting at 2024 and a retrospective part with nested case-control studies. Bus drivers will be invited through three complementary channels: unions, companies, and social media. The eligibility screening, information, and consent form signature and registration will be conducted using the study web-site modules. Registered bus drivers will first receive a comprehensive inclusion questionnaire, then a yearly follow-up questionnaire to assess and update the drivers' work histories. Validated self-reported questionnaires will be used for assessing additional health outcomes (e.g., stress, sleep problems, musculoskeletal disorders, burnout) and individual, occupational and live-style related factors (e.g., personality, ICT use, physical activity). Hospital records (with diagnosed diseases, diagnosis dates and treatments) centralized since 2000 by the Swiss Federal Statics Office will be used for assessing disease prevalence, incidence and case-control status. Advanced statistical analysis will be conducted to address etiological and methodological questions (e.g., individual and joint causal effects of multiple exposures and exposure components; time-varying exposure and outcome variables and confounders mixtures). CONCLUSIONS The yearly assessment of both exposure and health outcomes should enable capturing changes in work conditions and their effects on bus drivers' health and well-being over time and facilitate the tailoring, implementation and evaluation of preventive interventions.
Humans ; Switzerland/epidemiology* ; Prospective Studies ; Occupational Exposure/statistics & numerical data* ; Occupational Diseases/epidemiology* ; Cohort Studies ; Motor Vehicles ; Research Design ; Retrospective Studies ; Case-Control Studies ; Occupational Health ; Adult ; Male ; Female

BACKGROUND: Technological innovations in the public transport sector are increasingly leveraged to support the goals of environmental sustainability and public health. Eco-driving assistance (EDA) systems represent one such intervention, aimed at reducing fuel consumption, emissions, and operating costs while improving passenger comfort. However, the potential unintended impacts of EDA technologies on driver health and well-being remain understudied. The EDA Trial, part of the EU-funded INTERCAMBIO project, seeks to evaluate whether the use of EDA systems may introduce new psychosocial stressors for professional drivers, with implications for occupational and public health. METHODS: The EDA tested in this trial is called "NAVIG". Buses will be assigned randomly. Operating EDA-equipped vehicle will be considered as intervention condition, operating vehicle without EDA as control. Each participant will be monitored for 10 working days maximum to accumulate at least 5 intervention shifts during the trial. Heart rate variability (HRV) will be continuously recorded during working hours to assess autonomous stress responses. The root mean square of successive differences (RMSSD) will be averaged over intervention and control shifts to enable within-subject comparisons between intervention and control conditions. Subjective stress levels will be evaluated using the self-report instruments: Cohen's perceived stress scale at baseline and visual analogous scale at baseline and daily. Moreover, neuroendocrine stress biomarkers (salivary cortisol and cortisone) will be collected repeatedly across shifts, as additional outcomes. Mixed-effects models with participant's ID as a random effect variable will be used to compare stress outcomes between EDA and non-EDA driving conditions. Models will be adjusted for potential confounders. RESULTS: A sample size of 26-40 participants was estimated to provide 80% power (α = 0.05) to detect differences of 12-15% between conditions. Ethical approval was obtained from the Swissethics (CER-VD 2024-01573), and participant recruitment is ongoing, with 27 drivers enrolled as of June 2025. CONCLUSIONS: This study will provide empirical evidence on the potential health trade-offs associated with implementing eco-driving technologies in real-world settings. By assessing physiological and psychological stress responses to EDA, the trial supports a more integrated approach to environmental technology evaluation-one that considers not only energy efficiency but also the health and sustainability of the workforce. TRIAL REGISTRATION The trial was registered in the ClinicalTrials.gov database (NCT06688721).
Humans ; Automobile Driving/psychology* ; Stress, Psychological ; Motor Vehicles ; Adult ; Male ; Randomized Controlled Trials as Topic ; Female