Vulnerable user safety is an important public-health issue; most of the accidents involving trucks and vulnerable users in urban areas have devastating consequences for users. The goal of the VIVRE2 project (anr05-pdit) is the study and design of a driving-assistance system for truck drivers to significantly reduce the number of these accidents. The design of this system was inspired by the User-Centered Design Approach, based on iterative steps described by Maguire (2001). To plan the human-centered process, a methodology was defined to allow several specification versions. This methodology included tool creations to apply this approach in an industrial context. The first one, named Integration Platform, is dedicated to the integration of the driving assistance inside the driving simulator environment to facilitate the iterative process. The second one, named Dynamic Scenario Generator, is dedicated to the design of the assistance system itself. It allowed the verification that a single system, including active controls, is capable of answering the set of use case requirements. To identify critical-use cases, the context of use was analyzed not only from the point of view of drivers but also, from that of vulnerable users. Requirements were defined to improve the way in which the system is used during the driving task according to task constraints (temporal aspect, complexity, attentional demand). In the design solution, an adaptive technology, taking driver’s behavior into account was used to adapt the HMI alerts and active controls. Multiple evaluations were performed to iteratively improve the functioning of the system. This experience has shown that around the truck driving simulator of Renault trucks, designers, psychologists, and ergonomists were able to work together to implement strategies of driver assistance, to assess the relevance and effectiveness of a homogeneous system for the use cases. The designed system was evaluated using the dynamic driving simulator; its acceptability by the driver, and its effectiveness in critical situations (89 % of the accidents were avoided on all the experiments) were demonstrated.