Abstract The Canadian railway industry regularly has to deal with critical incidents (CI) involving collisions with people or vehicles. Such incidents may result not only in serious injuries or even fatalities, but also cause mental health problems for the locomotive engineers and conductors involved. Every year, approximately 20 people in Quebec and around a hundred in Canada as a whole lose their lives in collisions with trains. In addition to fatal events, an unknown number of incidents also occur in which people are injured or property is damaged. Most train engineers and conductors will be exposed to this type of event at least once in their careers. When a critical incident of this nature occurs, they are witnesses, victims, stakeholders and often first responders, all at the same time. A significant percentage of locomotive engineers and conductors soon get back to a satisfactory operating level in both their personal and professional lives and have very few psychological, social or functional after-effects. However, the recovery time after a CI can be quite long, and employees may require support during this period. In addition, between 4% and 17% of these employees will experience more severe problems, including depression, acute stress disorder, posttraumatic stress disorder or anxiety. Several clinical approaches are effective in mitigating posttraumatic symptoms, and a large part of the research has focused on them. In contrast, needs are less well known and resources rarer for those who do not actually develop posttraumatic stress, but struggle with significant undiagnosed adverse effects. A few studies have examined the critical incident management and employee support protocols (CIMESPs) implemented by employers, and most of them have recommended the adoption of practices aimed at reducing the potential impact of critical incidents on employees and shortening their recovery period. Nevertheless, although these protocols are based on studies of CI after-effects and employee needs, they have not yet been subjected to empirical evaluation. Assessments of this kind are necessary to determine the key elements of these protocols that have a positive impact on employee recovery and to promote recommendations based on scientific findings. The aim of this project was to assess the CIMESPs that have already been implemented in the Canadian rail industry and their impact on the recovery paths of employees who have been involved in critical incidents and to propose key, empirically based practices to attenuate adverse effects and reduce the risk of posttraumatic reactions. Seventy-four locomotive engineers and conductors who experienced a CI were recruited to take part in the prospective study. They were interviewed four times over a six-month period. Meanwhile, nine supervisors who managed critical incidents were interviewed twice over a three-month period. A mixed-method approach was used to analyse the collected data, with statistical and qualitative analyses being combined to achieve a good understanding of the links between critical incidents, CIMESPs and post-CI recovery. The perceptions, needs and recommendations of supervisors who are on the front line of applying protocols and providing support are also presented. The results indicate that existing CIMESPs are implemented partially or unevenly, depending on the employers, provinces and CI types. In CIs without fatalities, for instance, management and support protocols are not completely followed, even if employee health is affected. CIs affect employees in a wide variety of ways. The research team was able to establish five distinct recovery paths: no adverse effects, adverse effects that disappear within the month following the CI, adverse effects that gradually decline and disappear within the three months following the CI, adverse effects that plateau between one and three months afterwards and then disappear, and adverse effects that are still present after six months. Overall, two thirds of employees see the adverse effects of a CI dissipate fairly quickly in the month following the CI, 20% still feel significant effects after three months (plateau path and effects that persist after six months), while that proportion falls to 13% after six months. These effects are not negligible and affect employees’ cognition (concentration, rumination, distraction), energy (fatigue, trouble sleeping) and emotions (guilt, grieving). They may also interfere with employees’ ability to perform their jobs effectively. Differences in CIMESP application provide opportunities for assessing the role of the protocols in the post-CI recovery process. The study results show that management protocols can have an effect on the recovery process. The following factors tend to foster an acceleration of the process: the presence of a supervisor on site; a supervisor taking charge at the scene of the CI; the various stakeholders showing respect and empathy toward those affected; no pressure on employees to get them to continue working or to return to work before they are ready; automatically removing employees from the scene of the CI, sending them home, and granting them recovery leave; proactive offering of support by the employee assistance program; clear procedure for return to work and assessment of employee’s readiness to resume occupational duties; deferred offer of support if needed; follow-up after return to work and a positive work environment. These elements should constitute the core structure of effective protocols in the railway industry. The study shows that CI management and post-CI support provided by employers are key factors in promoting employee recovery. These are attitudes and actions that employers can influence and that can be applied fairly easily, without entailing prohibitive costs for companies. Other factors, such as social support or the complexity of the CI, are harder for employers to influence. Railways have protocols that already include most of the actions deemed to be effective. Following those protocols assiduously is a first step toward improving current practices and mitigating the adverse effects of CIs.