The Road Freight Transport (RFT) sector is continuously evolving, being confronted with intense competition and growing pressure from customers and suppliers, tight delivery times, and many regulations. All these factors lead the RFT sector to face multiple economic, environmental, and safety challenges. In these companies, the planner has a central position. The tasks of planner include supervising the transport round, keeping contact with the drivers during delivery, providing new instructions when needed, ensuring order follow-up with customers, etc. Such tasks require a high cognitive load which implies difficulties for planners in assessing the consequences of their decisions in terms of economic, environmental, and safety dimensions. In this study, principles of prospective ergonomics have been tested to support the transition from a human-based decision making to a computer-supported decision-making to anticipate the future computer-supported decision-making. We focused on the effect of system transparency and reliability. We confronted six planners with planning problems. We modified information available on planning to provide high and low levels of transparency. Starting from real issues, we also generated reliable and unreliable solutions (for these latter by adding invalid data). For each problem, planners were asked to assess the quality of the proposed solutions and indicators. The results showed than planners give a higher score to reliable scenarios displaying reliable information than to a less reliable scenario in which information is modified. This assessment of scenario is more adequate and easier with high transparency than with low transparency of information.